In this section, the weapons used to destroy the Twin Towers and the other buildings in the WTC complex, as well as the weapon that caused the massive crater and seismic activity in Shanksville, Pennsylvania, are examined here.
Fatman – bomb dropped on Nagasaki
IMAGE: Nagasaki-type Atomic Bomb “Fatman”. The Nagasaki atomic bomb was nicknamed “Fatman” because of its shape. The TNT implodes on the core of plutonium, causing nuclear fission.
The Bomb Called “Little Boy”
Through self-sustaining nuclear fission (chain reaction), an atomic bomb emits a huge amount of energy instantaneously.
The atomic bomb dropped on Hiroshima was a gun-barrel bomb. The uranium was divided into two pieces, both less than a critical mass and placed at either end of a cylinder. When one piece was fired into the other, critical mass was achieved.
Though the bomb was long and thin in shape, it grew shorter over the course of the project. Hence, the final bomb was called “Little Boy.”
Shockwave video: “Little Boy,” the Atomic Bomb Dropped on Hiroshima
VIDEO: “Little Boy” the atomic bomb dropped on Hiroshima (Dailymotion)
Images were taken from the swf file above
RNEP Nuclear Bunker Buster
The nuclear fission reaction
VIDEO: “Nuclear fission reaction” (Dailymotion)
Caption: “When a neutron strike the nucleus of a uranium (or plutonium) atom, the nucleus splits, releasing two or three neutrons and a large amount of energy (as radiation, heat, etc.). The neutrons thus released strike other nuclei, and the repetition of this nuclear fission is known as a “chain reaction.” When a chain reaction occurs in an extremely short time, a tremendous amount of energy is released. The atomic bomb utilized this synergy as a weapon.” (URL)
Watch larger version of video here
IMAGE: Fat Man – internal components
Fat Man: Implosion-type bomb
IMAGE: “The initial design for the plutonium bomb was also based on using a simple gun design (known as the “Thin Man”) like the uranium bomb. As the plutonium was produced in the nuclear reactors at Hanford, Washington, it was discovered that the plutonium was not as pure as the initial samples from Lawrence’s Radiation Laboratory. The plutonium contained amounts of plutonium 240, an isotope with a rapid spontaneous fission rate. This necessitated that a different type of bomb be designed. A gun-type bomb would not be fast enough to work. Before the bomb could be assembled, a few stray neutrons would have been emitted from the spontaneous fissions, and these would start a premature chain reaction, leading to a great reduction in the energy released. Seth Neddermeyer, a scientist at Los Alamos, developed the idea of using explosive charges to compress a sphere of plutonium very rapidly to a density sufficient to make it go critical and produce a nuclear explosion.” URL: http://www.atomicarchive.com/Fission/Fission9.shtml
The Structure and Explosive Mechanism of the Hiroshima Bomb
Caption: “The Hiroshima Bomb (Little Boy). About three meters long and weighing about four tons, the bomb dropped on Hiroshima was called “Little Boy” because it grew shorter over the course of the project … The Hiroshima bomb was designed to use gunpowder to blast one piece of uranium 235 into another, in order to reach a super-critical mass instantly. Roughly 50 kilograms of uranium 235 were packed into the bomb, of which less than one kilogram instantly underwent sustained nuclear fission, releasing energy equivalent to 16,000 tons of chemical high explosives. Highly sensitive radar attached to the bomb enabled it to explode at the altitude calculated to maximize the effects of the explosion.” URL: http://www.pcf.city.hiroshima.jp/virtual/cgi-bin/museum.cgi?no=0029&l=e
The Hiroshima Bomb (Little Boy)
IMAGE: “About three meters long and weighing about four tons, the bomb dropped on Hiroshima was called “Little Boy” because it was relatively thin.” URL: http://www.pcf.city.hiroshima.jp/virtual/cgi-bin/museum.cgi?no=0029&l=e
The Hiroshima Bomb
Little Boy – a gun-type bomb
Caption: “In essence, the Little Boy design consisted of a gun that fired one mass of uranium 235 at another mass of uranium 235, thus creating a supercritical mass. A crucial requirement was that the pieces be brought together in a time shorter than the time between spontaneous fissions. Once the two pieces of uranium are brought together, the initiator introduces a burst of neutrons and the chain reaction begins, continuing until the energy released becomes so great that the bomb simply blows itself apart.” URL: http://www.atomicarchive.com/Fission/Fission7.shtml
Even a sub-kiloton bomb can cause considerable damage
Reasons for a fizzle are examined. A fizzle yield is a yield that is less than expected. A nuclear bomb with a fizzle-yield could have caused considerable damage in the WTC attacks. It’s possible that the perpetrators deliberately employed a bomb that would “fizzle” so as to limit the scope of the nuclear destruction and disguise the fact that a nuclear device was used. In other words, the perpetrators would have selected a detonation size that would be less than typically seen for a nuclear attack but of a size that would cause the damage they wanted to cause. A “fizzle-yield” nuclear bomb would fit the bill: it would cause a detonation half-way between that caused by conventional explosive devices and a small (1 kiloton) nuclear bomb.
Reasons for a fizzle – more
Reason for a fizzle – chain reaction starts too soon
On North Korea’s nuclear test
IMAGE: Aerial view of the WTC site in lower Manhattan
Seismic and decoupling
Detonation of a sub-kiloton bomb would cause destruction of several buildings although it would not flatten a city. The radiation that would have been released was not a desired effect. The attack on the WTC was not a terrorist attack like the one described below, where the aim was to simply cause as many deaths as possible. The terrorists in the 9/11 attack faced restrictions of having to hide the authorship of the attacks. Saudis did not have nuclear capability at the time of the 9/11 attacks so the destruction of the buildings had to look like they had been caused by something else.
Detecting nuclear tests
Caption: Seismic detectors form the backbone of the nuclear monitoring system.
Information is collected from 500 seismic detectors around the world. Scientists are tasked with distinguishing earthquakes and nuclear testing blasts.
The equivalent magnitude of an earthquake and nuclear explosion
Decoupling – methods
Disguising nuclear testing can be done by decoupling. Another method is to camouflage the blast with mining explosions (mine masking). Decoupling requires exploding the device near a large underground cavity. The “Bathtub” underneath the WTC complex could have served as the large underground cavity that served to reduce the seismic activity of the nuclear detonations in the WTC attacks.
Decoupling – effects
Decoupling can reduce the magnitude of a seismic reading. A fully-decoupled 1 kiloton nuclear test can cause an earthquake of magnitude 2.7. An earthquake of this magnitude is rarely felt by anyone.
IMAGE: The Bathtub. This underground basement held six floors of a parking station, a metro line and offices. This space underneath the towers would have acted as a decoupling cavern for any bomb detonated within or above it.
Report on the seismic recordings of Ground Zero
The seismic recordings during the collapse of the towers were 2.1 and 2.3. These recordings are consistent with the detonation of a small nuclear device. In contrast, the recordings obtained during the plane crashes were 0.9 and 0.7. These recordings were not of a sufficient magnitude to cause the collapse of buildings.
Seismic recordings captured
DPRK Nuclear Test 10-9-06: seismic record
Comparisons of signals from different sources
Although the signals from the WTC collapse and earthquakes are of similar magnitude, the character of the seismographs are quite different. Differences in P and S waves are observed.
The above is an html-version of the following pdf-document:
Differences between seismographs of nuclear explosions and earthquakes
Detection of nuclear testing has increased in reliability
Detonations of yields of a kiloton can be detected anywhere on Earth.
Seismic disturbances of nuclear blasts
9/11 WTC collapses produced seismic disturbances equivalent to a 4.2 magnitude earthquake. A magnitude of that size would indicate a nuclear blast of 1-kiloton yield.
Seismic recordings of underground nuclear blasts
The explosion recorded in the 9/11 WTC attacks was the equivalent of a 4.2 earthquake and would translate into an explosion of 1,000 tons of TNT.
P and S waves are the key in distinguishing earthquakes and nuclear explosions
The seismograph of the World Trade Center tower collapses compared with the seismograph of nuclear test
Img: http://www.unitedstatesaction.com/Nuke-Test-vs-Earthquake.jpg URL: http://www.unitedstatesaction.com/nuclear-seismic-studies.htm Source: Science and Technology Review Dec 1998 http://www.llnl.gov/str/pdfs/09_98.pdf
Img: http://www.unitedstatesaction.com/Seismic-Nuke-vs-Earthquake.jpg URL: http://www.unitedstatesaction.com/nuclear-seismic-studies.htm Source: http://www.calit2.net/index.php Distributed Seismic and Radionuclide Sensor Network
South Tower collapse and North Korean nuclear test
Caption: Figure 3: Record section of vertical-component seismograms from stations in Fig. 2 following collapse of north Tower of WTC. Zero corresponds to computed origin time of 10:28:31 EDT. Data filtered for passband 0.5 to 10 Hz. Three velocities indicated by dotted lines.
Caption: Figure 3: Record section of vertical-component seismograms from stations in Fig. 2 following collapse of north Tower of WTC. Zero corresponds to computed origin time of 10:28:31 EDT. Data filtered for passband 0.5 to 10 Hz. Three velocities indicated by dotted lines. Img: http://guardian.150m.com/wtc/seismic/kim-wtc-3.jpg URL: http://guardian.150m.com/wtc/seismic/small/WTC_LDEO_KIM.htm
Caption: Seismograph of North Korean nuclear test. Modified image from URL: http://www.nytimes.com/2009/05/26/world/asia/26threat.html – NY Times: Seismic Readings Point to a Small Nuclear Test (May 25, 2009)
Caption: Seismic Readings Point to a Small Nuclear Test (May 25, 2009) Img: http://graphics8.nytimes.com/images/2009/05/26/world/26threat.600.jpg URL: http://www.nytimes.com/2009/05/26/world/asia/26threat.html – NY Times
Img: http://guardian.150m.com/wtc/seismic/small/kim-wtc-1.jpg URL: http://guardian.150m.com/wtc/seismic/small/WTC_LDEO_KIM.htm Caption: Collapse of South Tower
Plane impacts probably involved explosions
Caption: Seismic Readings Point to a Small Nuclear Test (May 25, 2009). Modified image from http://graphics8.nytimes.com/images/2009/05/26/world/26threat.600.jpg URL: http://www.nytimes.com/2009/05/26/world/asia/26threat.html – NY Times.
Comparisons with other nuclear events
Caption: Onset of P waves from a Soviet underground nuclear test monitored at a relay station in England. Img: http://www.reformation.org/seismic-waves2.jpg URL: http://www.reformation.org/ground-zero.html (Ground Zero-The Nuclear Demolition of the Twin Towers – Copyright © 2007 by Niall Kilkenny)
Reversed Rayleigh Waves
Reversed Rayleigh waves are consistent with an implosion rather than an explosion.
Caption: Record section of vertical-component seismograms from stations in Fig. 2 following collapse of north Tower of WTC. Zero corresponds to computed origin time of 10:28:31 EDT. Data filtered for passband 0.5 to 10 Hz. Three velocities indicated by dotted lines. Img: http://guardian.150m.com/wtc/seismic/kim-wtc-3.jpg URL: http://guardian.150m.com/wtc/seismic/small/WTC_LDEO_KIM.htm
Image: http://www.iris.edu/hq/gallery/d/4195-2/one-pager-fig.jpg URL: http://www.iris.edu/hq/gallery/photo/4193 and Image: http://img19.imageshack.us/img19/1914/wtcseismicby3.jpg URL: http://letsrollforums.com/911-world-trade-center-t16686p20.html
Comparison between North Korean test and World Trade Center Tower collapses
Caption: DPRK’s seismic signature of their nuclear test Img: http://i2.photobucket.com/albums/y2/mrsdudara/dprknuke.gif URL: http://www.abovetopsecret.com/forum/thread650062/pg2
Caption: Seismic record of explosion from digital station Vladivostok
Source: CEME – Geophysical Service of Russian Academy.
Underground nuclear explosion appears in the seismograph
A sharp spike of short duration appears in a nuclear explosion, says a seismologist.
Other graphs of seismic disturbances at the World Trade Center
Other seismographs of Twin Tower Collapses
Caption: 1st collapse south tower Img: http://www.911myths.com/assets/images/seismic_collapse_103.gif URL: http://www.911myths.com/html/seismic_record.html
Audio accords with the seismic evidence
Booms heard before collapse
VIDEO: Rick Siegel 9-11 Eyewitness-Booming sounds Dailymotion
Audio wave and seismic record of the North Tower
VIDEO: 911 Eyewitness video of the audio wave for the North Tower Dailymotion
Audio wave supports explosives
VIDEO: 911 Eyewitness – Sound analysis shows explosives Dailymotion
Witnesses reported rumbling and dust clouds before collapse
VIDEO: 911 Eyewitness – Witnesses reported rumbling and dust clouds before collapse Dailymotion
Complete Rick Siegel documentary
VIDEO: Rick Siegel 9 11 Eyewitness Video ArchiveOrg
Caption: Seismograms recorded during the explosion (red wave) and a recent earthquake (blue wave) near that experiment show the different seismic patterns produced by these geologic disturbances.
Differences between nuclear and earthquake seismic signatures
Comparing the seismic records of World Trade Center collapses and Indian nuclear test
More comparisons with Indian nuclear test
http://www.serendipity.li/wot/pop_mech/seismic_record.png URL: http://www.serendipity.li/wot/pop_mech/reply_to_popular_mechanics.htm Img 2: http://i190.photobucket.com/albums/z235/newbie_bucket/c6b6812d.jpg URL: http://184.108.40.206/focus/news/2629020/posts Alternate URL: http://www.metafilter.com/23239/The-Pacific-Northwest-Seismograph-Network
http://www.serendipity.li/wot/pop_mech/seismic_record.png URL: http://www.serendipity.li/wot/pop_mech/reply_to_popular_mechanics.htm Img 2: http://i190.photobucket.com/albums/z235/newbie_bucket/c6b6812d.jpg URL: http://220.127.116.11/focus/news/2629020/posts Alternate URL: http://www.metafilter.com/23239/The-Pacific-Northwest-Seismograph-Network
http://www.serendipity.li/wot/pop_mech/seismic_record.png URL: http://www.serendipity.li/wot/pop_mech/reply_to_popular_mechanics.htm Img 2: http://i190.photobucket.com/albums/z235/newbie_bucket/c6b6812d.jpg URL: http://18.104.22.168/focus/news/2629020/posts Alternate URL: http://www.metafilter.com/23239/The-Pacific-Northwest-Seismograph-Network
Img 2: http://i190.photobucket.com/albums/z235/newbie_bucket/c6b6812d.jpg URL: http://22.214.171.124/focus/news/2629020/posts Alternate URL: http://www.metafilter.com/23239/The-Pacific-Northwest-Seismograph-Network Img 2: http://www.911myths.com/assets/images/wtc_pal_ehe_500.gif URL: http://www.911myths.com/html/seismic_proof_.html
Img 2: http://i190.photobucket.com/albums/z235/newbie_bucket/c6b6812d.jpg URL: http://126.96.36.199/focus/news/2629020/posts Alternate URL: http://www.metafilter.com/23239/The-Pacific-Northwest-Seismograph-Network Image 2: http://www.911myths.com/assets/images/wtc_pal_ehe_500.gif URL: http://www.911myths.com/html/seismic_proof_.html
Caption: Seismic shockwaves from the latest test were recorded in South Korea. IMG: http://newsimg.bbc.co.uk/media/images/45825000/jpg/_45825538_nuclearseizemic_226afp.jpg URL: http://news.bbc.co.uk/2/hi/asia-pacific/6033893.stm
Large factors can be achieved by decoupling
IMG: Seismic waveform nuclear vs. earthquake URL: http://www.calit2.net/technology/features/sensorNetClass/radio.pdf
Richter magnitude and TNT-equivalent seismic energy yield
|Richter Magnitude||TNT for Seismic Energy Yield||Example (approximate)|
|-1.5||6 ounces||Breaking a rock on a lab table|
|1.0||30 pounds||Large Blast at a Construction Site|
|1.5||320 pounds||Large Quarry or Mine Blast|
|4.0||1,000 tons||Small Nuclear Weapon|
|4.5||5,100 tons||Average Tornado (total energy)|
|5.5||80,000 tons||Little Skull Mtn., NV Quake, 1992|
|6.0||1 million tons||Double Spring Flat, NV Quake, 1994|
|6.5||5 million tons||Northridge, CA Quake, 1994|
|7.0||32 million tons||Hyogo-Ken Nanbu, Japan Quake, 1995; Largest Thermonuclear Weapon|
|7.5||160 million tons||Landers, CA Quake, 1992|
|8.0||1 billion tons||San Francisco, CA Quake, 1906|
|9.0||32 billion tons||Chilean Quake, 1960|
|10.0||1 trillion tons||(San-Andreas type fault circling Earth)|
|12.0||160 trillion tons||(Fault Earth in half through center, OR Earth’s daily receipt of solar energy)|
Seismic detection of nuclear tests can pose some challenges
Analysis of nuclear test seismic wave pattern
Comparison of the aircraft impacts and collapse of towers
Oral reports of ground shaking before collapse
Brian Becker — Lieutenant (F.D.N.Y.) [Engine 28] We felt — our whole building that we were in, when World Trade Center 2 collapsed, that was the first one to collapse. We were in World Trade Center 1. It was a tremendous explosion and tremendous shaking of our building. We thought it was our building maybe collapsed, there was a collapse above us occurring. It was tremendous shaking and like everybody dove into this stairwell and waited for, I guess, 20, 30 seconds until it settled, and that was our experience of the other building collapsing.
Michael Beehler — Firefighter (F.D.N.Y.) [Ladder 110] I was by I guess the outer part of the building and I just remember feeling the building starting to shake and this tremendous tremendous like roar and I just — I kind of didn’t even notice it, but like out of the corner of my eye, I saw out of the building, I saw a shadow coming down. At that point I thought it was the upper part of the north tower that had just basically like toppled over, fell off. I didn’t actually see the building part go by me, because I think I was on the opposite side. But I just remember feeling this tremendous tremendous shake and hearing this, like, noise. Again I can’t describe. What I did was I ended up running out.
Jody Bell — E.M.T. (E.M.S.) I lost track of time. You start to hear this rumble. You hear this rumble. Everything is shaking. Now I’m like, what the hell could that be. I’m thinking we’re going to get bombed. This is an air raid. You hear this thunder, this rumbling. Then you see the building start to come down. Everybody’s like, “Run for your lives! The building is coming down!” At that moment when that building was coming down, I was strapping a patient onto a stair chair.
David Blacksberg — E.M.T. (E.M.S.) I lost track of time of when the second building was coming down. It sounded like one big rumble, and then it just sounded like it just continued, and I was — I wasn’t really paying attention. I was looking at the sound.
Nicholas Borrillo — Firefighter (F.D.N.Y.)on 23rd floor of North Tower:
Then we heard a rumble. We heard it and we felt the whole building shake. It was like being on a train, being in an earthquake. A train is more like it, because with the train you hear the rumbling, and it kind of like moved you around in the hall. Then it just stopped after eight or ten seconds, about the time it took for the building to come down.
Peter Cachia — (E.M.S.) [Battalion 4] I was like a little too close to the tower when it started coming down, because when I started running, I knew I was too close and I really didn’t think I was going to get out of there. So about halfway up Liberty Street I saw a truck, I guess an SUV. It wasn’t a police or a fire vehicle. It was just a car that was parked there. I went under the truck while the tower came down and the ground was shaking and the truck was shaking and I thought that was it for me. I thought I was done. I stayed under there until I guess everything was over.
Paul Curran — Fire Patrolman (F.D.N.Y.)North Tower:
I went back and stood right in front of Eight World Trade Center right by the customs house, and the north tower was set right next to it. Not that much time went by, and all of a sudden the ground just started shaking. It felt like a train was running under my feet.
The next thing we know, we look up and the tower is collapsing.
Timothy Julian — Firefighter (F.D.N.Y.) [Ladder 118] You know, and I just heard like an explosion and then cracking type of noise, and then it sounded like a freight train, rumbling and picking up speed, and I remember I looked up, and I saw it coming down.
I made it right to the corner, and there’s a column right there, and I was with my guys. We all made it to like the column, and I remember it was plate glass behind me, and I’m thinking I’m going to get hit by this glass and like a porcupine. I’m going to get it, you know, but nonetheless, it rumbled.
It was the loudest rumbling I ever heard. The ground shook, and I got thrown down, and I remember it just got black, and I got knocked down. I remember geing buried.
Bradley Mann — Lieutenant (E.M.S.) Shortly before the first tower came down, I remember feeling the ground shaking. I heard a terrible noise, and then debris just started flying everywhere. People started running.
Keith Murphy — (F.D.N.Y.) [Engine 47] At the time, I would have said they sounded like bombs, but it was boom boom boom and then the lights all go out. I hear someone say oh, s___, that was just for the lights out. I would say about 3, 4 seconds, all of a sudden this tremendous roar. It sounded like being in a tunnel with the train coming at you. It sounded like nothing I had ever heard in my life, but it didn’t sound good. All of a sudden I could feel the floor started to shake and sway. We were being thrown like literally off our feet, side to side, getting banged around and then a tremendous wind starting to happen. It probably lasted maybe 15 seconds, 10 to 15 seconds. It seemed like a hurricane force wind. It would blow you off your feet and smoke and debris and more things started falling.
The “Bathtub” and slurry wall of the World Trade Center
Genesis of the Bathtub
The WTC complex consisted of seven buildings on a 16-acre site in lower Manhattan. The deep basement (bathtub) portion of the site covers a four-city block (980 foot) by two-city block (520 foot) area some 200 feet from the east shore of the Hudson River (Figure 1). The deep basement occupies only about 70 percent of the 16-acre WTC site and is just west of the place where the Dutch landed in 1614. The size and depth of the deep basement and the alignment of the perimeter wall were dictated by several requirements: the construction of a new interstate commuter railroad (PATH) station parallel to the Greenwich Street east wall; support for an operating New York City subway tunnel located just outside the east wall; protection of the entry points of two 100-year old, 17-foot diameter PATH tunnels on the east and west; and the foundation of the twin towers (WTC 1 and WTC 2) on bedrock within the excavation (Figure 2).
The geology of the WTC site varies from east to west. On the east (Greenwich Street), 15 to 30 feet of fill cover as much as 20 feet of glacial outwash sand and silt, below which are 5 to 20 feet of glacial till/decomposed rock. The Manhattan schist bedrock is found at depths of 65 to 80 feet. A knoll of quartzite rock intrudes into the site at the southeast corner. On the west (West Street), the fill is 20 to 35 feet thick and is underlain by 10 to 30 feet of soft organic marine clay (river mud). Below the river mud is a 20-foot thick layer of glacial outwash sand and silt and 5 to 20 feet of glacial till/decomposed rock. Bedrock is found at depths of 55 to 75 feet. Groundwater levels were within several feet of ground surface. [..]
The basement was bounded by a 3,500-foot long, 3-foot thick slurry wall (perimeter wall) constructed from grade and socketed into rock located at depths of as much as 80 feet.
[The slurry walls contained bentonite at first which was replaced with concrete.]
DIAPHRAGM WALL CASE STUDY #4: World Trade Center Recovery, NY, NY
The tragic events of 9/11/01 have left few people untouched. One of the greatest “heroes” of the day has been the “bathtub” of the World Trade Center, being able to resist the tremendous forces generated by the destruction while holding back the Hudson river from entering the New York City tunnel system. The “bathtub”, is actually a 3 ft thick (0.91 m) structural slurry wall that keeps water and soil out of the excavation.
Description: Img: http://www.deepexcavation.com/uploads/case_studies/WTC_TimesPhoto_Edited_1small.JPG URL: http://www.deepexcavation.com/en/4-world-trade-center World Trade Center Bathtub and Original Conditions (adapted from NY Times 9/18/01)
Caption: The bathtub contained the footprints of the Twin Towers and Buildings 3 and 6.
Caption: This illustration shows a cross-section of the bathtub tall. The diagonal lines represent the post-tensioned tie-backs: cables that resist pressure pushing inward on the bathtub.
Caption: This photograph shows the bathtub wall after most of the rubble from the 9/11/01 attack was removed. Portions of basement floors are visible in the right-hand side of the photograph.
Bathtub covered 9 blocks
About half of the superblock that the World Trade Center occupied contained a deep basement, the so-called bathtub. It was a skewed rectangle with sides about 980 and 520 feet, and a depth of about seven stories.
The bathtub is the 9-block area of the World Trade Center site that is excavated down to bedrock and hard soils and ringed by the slurry wall. The bathtub was created to enable the building of the Twin Towers’ foundations, and was ultimately filled with seven stories of basements housing the parking garage, mall, and building services. Since the ground water level at the World Trade Center site was just a few feet below the surface, while bedrock was about 70 feet below the surface, creating the bathtub required first building a 7-story dam below the water level of the adjacent Hudson River — the slurry wall. [..]
Four of the World Trade Center buildings — the Towers and Buildings 3 and 6 — rested on foundations entirely within the bathtub.
Building the slurry wall
The question was how to keep the Hudson out.
Jack Kyle, chief engineer at the Port Authority, came up with an answer. It was known as the slurry trench method. Excavating machines with clamshell buckets dug a three-foot-wide trench right down to bedrock 70 feet below. They did it in 22-foot-wide sections all the way around the site. As they removed fill from each section, they pumped in a slurry of water and bentonite, an expansive clay. The clay naturally plugged any holes in the sides of the dirt walls.
When they had fully excavated a section of the trench, workers slid a 25-ton, seven-story-high cage of reinforced steel into the section, then filled that portion of the trench with concrete from the bottom up. The yard-thick wall became known as the “bathtub,” though this bathtub was meant to keep water out, not in.
Caption: (1) Builders of the “bathtub” wall first excavated a three-foot-thick trench segment that was 65 feet deep by 22 feet wide and filled it with a stabilizing slurry. (2) They then lowered a giant steel cage into the trench, with attachment points for reinforcing tiebacks that were later anchored to bedrock outside the wall. (3) Finally, they poured in concrete, which, as it rose from the bottom up, forced out the temporary slurry.
The World Trade Center was built on bedrock
Caption: The soil on the island of Manhattan is perfect for building skyscrapers. In midtown Manhattan, BEDROCK is only about 10 feet or 3 meters deep. However, at the location of the Twin Towers in the lower part of Manhattan BEDROCK is about 100 ft or 30 meters deep. There is also the problem of water from New York harbor and the Hudson River. Midtown Manhattan was thus the IDEAL place to build the Twin Towers.
When it comes to demolition by nuclear weapons the deeper the foundation the better because depth of soil hides the effects of RADIATION: “By testing underground, man has placed a shield around most radioactive by-products from nuclear explosions. In contained underground detonations of fusion devices, radioactive products are trapped in cracked rock and rubble beneath the ground’s surface. The gaseous products such as water vapor, carbon dioxide, iodine, and tritium gradually cool. Most of the water and iodine condenses to a liquid. Neutrons promptly interact with lithium in the rock minerals to produce the radioactive isotope tritium (see Box 2.1), and this heavy isotope, in part, replaced ordinary hydrogen in water to form tritiated water. The radioactive water mixes with natural ground water and moves with it through the surface rock.”(Bolt, Nuclear Explosives and Earthquakes, pp. 83-84).
The Hiroshima Bomb
Because of its long, thin shape, the Hiroshima bomb was called Little Boy. The fissile material was uranium 235. The uranium was divided into two parts, both of which were below critical mass. It was a “gun barrel-type” bomb that used an explosive device to slam one portion of uranium into the other, instantly creating a critical mass.
When a critical mass is available, a chain reaction takes place instantaneously, releasing energy far beyond the capacity of ordinary explosives. The energy released by the Hiroshima bomb was originally thought to be equivalent to the destructive power of approximately 20,000 tons of TNT. Later estimates based on damage to buildings and studies of the bomb’s structure have reduced that figure to approximately 15,000 tons. It is believed that this enormous energy was released by the fission of slightly less than one of the 10 to 35 kilograms of uranium 235 in the bomb.
The Hiroshima Bomb (Little Boy)
Hiroshima Bomb Diagram
Length: Approx. 3 meters (120 inches)
Weight: Approx. 4 tons (9,000 lbs)
Diameter: Approx. 0.7 meters (28 inches)
Element: Uranium 235
Alternative link: http://www.cnduk.org/pages/ed%20old/atom.html
The Nagasaki Bomb
Compared to one used on Hiroshima, the Nagasaki bomb was rounder and fatter, so it was called “Fat Man.” The fissile material was plutonium 239. The plutonium was divided into subcritical portions and packed into a spherical case. To cause the chain reaction, gunpowder around the periphery of the case was used to force the units to the center. Thus, it was called an “implosion-type” bomb.
The fission of slightly more than one kilogram of plutonium 239 is thought to have released destructive energy equivalent to about 21,000 tons of TNT.
The Nagasaki Bomb (Fat Man)
Nagasaki Bomb Diagram
Length: Approx. 3.2 meters (128 inches)
Weight: Approx. 4.5 tons (10,000 pounds)
Diameter: Approx. 1.5 meters (60 inches)
Element: Plutonium 239
Caption: Project Plowshare sought to use peaceful nuclear explosions for civil engineering purposes. One proposal envisioned the nuclear excavation of a new Atlantic–Pacific canal in Central America. Some of the routes considered are shown in this map.
Plowshare and the quest for peaceful nuclear explosions became one of Livermore’s major programs in the 1960s. Initially, the program focused on large-scale earth-moving, or nuclear excavation, with the long-term goal of using nuclear explosions to excavate a new Atlantic-Pacific canal through Central America (Figure 6).
Peaceful nuclear explosions – Sedan test
Caption: Sedan test (underground test) only a small amount (of radioactivity) released into the atmosphere. (at 5:50 min). (Screen capture)
“(4:35) The results of Plowshare work in controlling and limiting the rate of radioactivity released by a nuclear explosion have been and continue to be highly encouraging.
Scientists have already determined that when a nuclear explosives are buried at a depth that will produce the biggest crater, a major part of the radioactivity is swallowed up in the rubble of the crater. But the most promising results have been gained by improving the design of the explosive itself and by improving emplacement techniques. Both of these specifically calculate to reduce the release of radioactivity.
In the 1962 Sedan event, for example, only a small fraction of the radioactivity produced by the explosion was released to the atmosphere. If Sedan were conducted with the improved design and techniques available today (1965), there would be even less radioactivity and more reduction is still expected. A hundred-fold reduction from the radioactivity levels from 1962 through more improvement in explosive design and emplacement techniques.
When this prediction is realized, it will mean that the main limitation of nuclear excavation projects will not be radiation. It will be other potential hazards of explosions, nuclear or conventional: the ground shock, the air blast, and the dust cloud (6:22 min).”
Layer cake design
Image from movie (dead link)
“In Andrei Sakharov’s Layer Cake design, several layers of light and heavy elements were alternated. High explosives surrounding the Layer Cake would be used to implode and ignite the atomic bomb at the center of the device. The atomic explosion would then set off a fusion reaction in the deuterium.”
Caption: “Implosion-type weapon. Fat Man, the Nagasaki bomb, used 13.6 lb (6.2 kg, about 12 fluid ounces or 350 ml in volume) of Pu-239, which is only 39% of bare-sphere critical mass. (See Fat Man article for a detailed drawing.) Surrounded by a U-238 reflector/tamper, the pit was brought close to critical mass by the neutron-reflecting properties of the U-238. During detonation, criticality was achieved by implosion. The plutonium pit was squeezed to increase its density by simultaneous detonation of the conventional explosives placed uniformly around the pit. The explosives were detonated by multiple exploding-bridgewire detonators. It is estimated that only about 20% of the plutonium underwent fission; the rest, about 11 lb (5.0 kg), was scattered.” URL: http://en.wikipedia.org/wiki/Nuclear_weapon_design
Camp Desert Rock
Image from video below:
VIDEO: Camp Desert Rock Dailymotion
At Camp Desert Rock in Nevada, the U.S. military began using smaller atomic blasts to learn how to fight a nuclear war. On April 22, 1952 approximately 2,000 Army personnel conducted maneuvers beneath the mushroom cloud of the Charlie nuclear detonation. The 31-kiloton explosion was one of the largest ever conducted in Nevada to that date. This government film claimed that with a few basic precautions, U.S. troops could fight and survive an atomic attack.
Alternative link: https://www.youtube.com/watch?v=yJ7rTzmV58s
Video: “Survival Town”
Caption: Survival Town atomic bomb blasts. Army destroys a fabricated American town. Real-size dolls are the only inhabitants in “Survival Town”.
“Survival City was built by the Army for Operation Cue. The goal of the test was to observe how houses, shelters, power lines, a radio tower, metal buildings, food, clothing, and actual people would survive at various distances away from a nuclear blast. Mannequins sourced from J. C. Penney, populated the city.
The May 5th 1955 explosion was dubbed Apple-2. The all-clear was finally given at 8:10am.
The 31 kilotons explosion blast area extended 3 miles out from Ground Zero. Approximately 6,000 spectators watched from about 6 miles. Army troops in tanks and trenches were positioned at a mere 2 to 3 miles from the epicenter.”
Stills from the video:
Video: “Atomic Doomtown”
VIDEO: Atomic Doomtown. Big dolls were the sole inhabitants of this town. Filming was done inside the house to show the effects of nuclear explosions on the interior of nearby houses. Nevada desert in 1955. Dailymotion | Youtube
Some stills from that video:
VIDEO Dailymotion | Youtube: Beginning in 1953 the Federal Civil Defense Adminstration, working with the Atomic Energy Commission, set up an atomic test program to investigate the effects of nuclear weapons on typical American homes and their furnishings. (“OperationCue1955”) Original movie link | Original URL
U.S. nuclear reactor locations
http://www.ki4u.com/nuclearsurvival/list.htm (dead link)
May be archived under http://www.radshelters4u.com
Caption: The yield of a hydrogen bomb is controlled by the amounts of lithium deuteride and of additional fissionable materials. Uranium 238 is usually the material used in various parts of the bomb’s design to supply additional neutrons for the fusion process. This additional fissionable material also produces a very high level of radioactive fallout.
Caption: Nuclear energy can also be released by fusion of two light elements (elements with low atomic numbers). The power that fuels the sun and the stars is nuclear fusion. In a hydrogen bomb, two isotopes of hydrogen, deuterium and tritium are fused to form a nucleus of helium and a neutron. This fusion releases 17.6 MeV of energy. Unlike nuclear fission, there is no limit on the amount of the fusion that can occur.
Portable nuclear munitions
Caption: Special Atomic Demolition Munition (SADM), a Navy and Marine Corps project that was demonstrated as feasible in the mid-to-late 1960s. The package shown was intended to be used by UDT/Seal Special Forces, delivered into water by parachute along with a two man team, then floated to the target, set in place and armed by hand. Designed to attack a harbor or other strategic location that could be accessed from the sea.
The answer to the existence question is certainly yes, at least for “trunk size” devices. Unclassified sources have reported that small nuclear devices were developed by both the United States and the Soviet Union during the Cold War, a direct result of the work on tactical nuclear weapons. [..]
The U.S. developed a class of devices called “Atomic Demolition Munitions” (ADM), intended for use as atomic land mines. ADMs were in the U.S. inventory from the late 1950’s until such weapons were phased out by arms-control agreements in the 1980’s. A version of the ADM for use by Special Forces, the “Special Atomic Demolition Munitions” (SADM), was suitcase or duffle bag size, weighing less than 100 pounds [..] The top photo on this page is from a declassified film showing a demonstration of the SADM in the late 1960s. [..]
The Soviet Union’s small nuclear devices were developed for nuclear mines and possibly for Spetsnaz attacks (Special Forces). In 1997, General Aleksandr Lebed claimed that the Soviet Union created one hundred and fifteen atomic demolition munitions (ADMs), low-yield, one kiloton devices that were small, portable, and without safety devices to prevent unauthorized detonation. Lebed further raised the issue of whether the ADMs were all in proper custody and accounted for. Others have contradicted Lebed — the issue is unsettled, but it is most likely that the Soviets did produce small atomic munitions, similar to the U.S. SADM.
An important point is that all nuclear devices require routine maintenance to remain viable. Small devices are no exception and, in fact, may require more frequent maintenance than larger weapons. Therefore, a diverted weapon from military stocks will become ineffective in a matter of a few years even if its control systems can be bypassed. The main danger, after the device has lost its original effectiveness, is its use as a source of weapons grade plutonium.
Caption: SADM packing case small atomic munition
Caption: H-912 transport container for Mk-54 SADM.
Text: A suitcase nuke is a tactical nuclear weapon which uses, or is portable enough that it could use, a suitcase as its delivery method. Synonyms include suitcase bomb, backpack nuke, mini-nuke, or pocket nuke. [..]
The lightest nuclear warhead ever acknowledged to have been manufactured by the U.S. is the W54, which was used in both the Davy Crockett 120 mm recoilless rifle–launched warhead, and the backpack-carried version called the Mk-54 SADM (Special Atomic Demolition Munition). The bare warhead package was an 11 in by 16 in (28 cm by 41 cm) cylinder that weighed 51 lbs (23 kg). It was, however, small enough to fit in a footlocker-sized container.
Background on Suitcase Nukes
A “suitcase” bomb is a very compact and portable nuclear weapon and could have the dimensions of 60 x 40 x 20 centimeters or 24 x 16 x 8 inches. The smallest possible bomb-like object would be a single critical mass of plutonium (or U-233) at maximum density under normal conditions. The Pu-239 weighs 10.5 kg and is 10.1 cm across. It doesn’t take much more than a single critical mass to cause significant explosions ranging from 10-20 tons. These types of weapons can also be as big as two footlockers. The warhead consists of a tube with two pieces of uranium, which, when rammed together, would cause a blast. Some sort of firing unit and a device that would need to be decoded to cause detonation may be included in the “suitcase.”
Another portable weapon is a “backpack” bomb. The Soviet nuclear backpack system was made in the 1960s for use against NATO targets in time of war and consists of three “coffee can-sized” aluminum canisters in a bag. All three must be connected to make a single unit in order to explode. The detonator is about 6 inches long. It has a 3-to-5 kiloton yield, depending on the efficiency of the explosion. It’s kept powered during storage by a battery line connected to the canisters.
http://www.unitedstatesaction.com/suitcase-nuclear.htm Source: http://www.nationalterroralert.com/suitcasenuke/ – Department of Homeland Security
http://www.nationalterroralert.com/suitcasenuke/ (Dept of Homeland Security)
Too Few Labs To Test ‘Dirty Bomb’ Fallout
Report Finds U.S. Lagging In Resources To Test For Radiation Exposure
AP) The U.S. has a shortage of laboratories to test the thousands of people who might be exposed to radiation if a “dirty bomb” detonated in a major city, according to a recent congressional investigation.
The federal government established 15 disaster scenarios for federal, state and local officials to plan for, including one in which a dirty bomb goes off in a major downtown area and potentially exposes 100,000 people to radioactive materials.
A dirty bomb would contain some radioactive material that could cause contamination over a limited area but not create actual nuclear explosions.
Should this happen in real life, America would not be able to quickly conduct tests for these people, because there are few labs capable of doing so in the country; and the tests available only address six of the 13 radiological isotopes that would likely be used in a dirty bomb, according to the report prepared for the House Committee on Science and Technology. Instead, it would take four years to complete all these tests, according to the report to be released Thursday. [..]
http://www.cbsnews.com/stories/2007/10/25/national/main3407373.shtml – Copyright AP WASHINGTON, Oct. 25, 2007
Caption: A congressional report found it would take four years to test the thousands of people who might be exposed to radiation of a dirty bomb detonated in a major downtown area. (CBS/AP)
Video: Declassified US Nuclear Test Film #31
“SADM Delivery by Parachutist/Swimmer (Special Atomic Demolition Munition) – The Special Atomic Demolition Munition (SADM) was a Navy and Marines project that was demonstrated as feasible in the mid-to-late 1960s, but was never used. The project, which involved a small nuclear weapon, was designed to allow one individual to parachute from any type of aircraft carrying the weapon package that would be placed in a harbor or other strategic location that could be accessed from the sea. Another parachutist without a weapon package would follow the first parachutist to provide support as needed.
The two-man team would place the weapon package in an acceptable location, set the timer, and swim out into the ocean where they would be retrieved by a submarine or other high-speed water craft. The parachute jumps and the retrieval procedures were practiced extensively.
The video shows a man in a wet suit donning his parachute, the weapon package, and a reserve parachute. After he jumps from the aircraft and is nearing the water, he drops the weapon package down on a 17-foot line to lessen the impact of his landing. He then floats the weapon package to the desired location.”
A still from that film:
VIDEO: American SADM
Dailymotion: American SADM. American Special Atomic Delivery Munitions. A shorter film (28 sec)
A still from that film:
Nuclear bunker buster – mini-nukes
The RNEP would be used on targets that may be immune to conventional weapons. Its backers claim it would create little contamination above ground, but critics say that it would produce huge amounts of nuclear fallout. The RNEP may also remove the distinction between a nuclear deterrent and conventional weapons, increasing the risk of a nuclear exchange.
US law prevents development of new “mini-nukes” that have an explosive yield of less than 5 kilotons. But the RNEP falls outside this ban because it is not a new weapon.
Rather, it will be a modification of an existing nuclear bomb, probably a highly modified B61, sources say, a weapon whose explosive yield can be set from anything between 0.3 and 340 kilotons. The bomb uses fission at low yields but is a fusion (hydrogen) bomb at high yields. The Hiroshima fission bomb had a yield of 12 kilotons.
Underground explosions are 10 to 15 times as effective against buried facilities as airbursts. A conventional bunker-buster is dropped from high altitude and hits the ground at enormous speed. It penetrates earth, rock and concrete before exploding. A nuclear version has the advantage of a far more powerful shock wave, increasing the depth of its destructive effect.
The US already has around fifty ‘penetrating’ nuclear weapons in its stockpile, but these can only reach a depth of six metres in earth. David Wright, a nuclear-weapons expert at the Union of Concerned Scientists in Washington DC, says this would not be nearly enough to contain the radioactivity.
“Even for a 0.3-kiloton explosion, you would need a burial depth of about 70 metres in dry soil and about 40 metres in dry, hard rock to contain the blast,” Wright says. An explosion at the maximum depth achievable so far would throw thousands of tonnes of highly radioactive debris into the air.
Nuclear bunker buster
Fig. 2 The Pentagon has a growing collection of high precision conventional weapons capable of defeating hardened targets. In this sled-driven test, the GBU-28 laser guided bomb with its improved BLU-113 warhead penetrates several meters of reinforced concrete.
Underground detonations limit collateral damage
Fig. 1 Diagrams like this one give the false impression that a low-yield earth penetrating nuclear weapon would “limit collateral damage” and therefore be relatively safe to use. In fact, because of the large amount of radioactive dirt thrown out in the explosion, the hypothetical 5-kiloton weapon discussed in the accompanying article would produce a large area of lethal fallout. (Philadelphia Inquirer/ Cynthia Greer, 16 October 2000.)
The B61-11 Nuclear Bomb
[M]ini-nuke advocates — mostly coming from the nuclear weapons labs — argue that low-yield nuclear weapons should be designed to destroy even deeper targets.
The US introduced an earth-penetrating nuclear weapon in 1997, the B61-11, by putting the nuclear explosive from an earlier bomb design into a hardened steel casing with a new nose cone to provide ground penetration capability. The deployment was controversial because of official US policy not to develop new nuclear weapons. The DOE and the weapons labs have consistently argued, however, that the B61-11 is merely a “modification” of an older delivery system, because it used an existing “physics package.”
The earth-penetrating capability of the B61-11 is fairly limited, however. Tests show it penetrates only 20 feet or so into dry earth when dropped from an altitude of 40,000 feet. Even so, by burying itself into the ground before detonation, a much higher proportion of the explosion energy is transferred to ground shock compared to a surface bursts. Any attempt to use it in an urban environment, however, would result in massive civilian casualties. Even at the low end of its 0.3-300 kiloton yield range, the nuclear blast will simply blow out a huge crater of radioactive material, creating a lethal gamma-radiation field over a large area.
Bunker buster in action
COMMENT: Notice that the blast is from a below ground explosion, similar to the WTC ones which were buried in the basement and were encased (in concrete and steel).
The fact that the explosions occur underground in the case of the bunker buster means that the effects of the nuclear explosion are all reduced (blast, thermal and radiation effects).
Bunker buster video
VIDEO Dailymotion: Nuclear bunker buster. From Federation of American Scientists. (“Nbbd_hi”)
Images from the video:
Robust Nuclear Earth Penetrator
“This animation depicts a proposed weapon with a one megaton yield. The funding for this weapon was cut in 2005 defense appropriations. However, the United States still has a B61-11 nuclear ‘bunker buster’ in its arsenal which has a 400 kiloton yield, which could still cause hundreds of thousands of deaths and spread radiation to other countries.”
“The Bush Administration has again requested funding from Congress to research a new type of nuclear bomb. The Robust Nuclear Earth Penetrator (RNEP) is a nuclear weapon that would burrow a few meters into rock or concrete before exploding and thus generating a powerful underground shock wave. Its hypothetical targets are deeply buried command bunkers or underground storage sites containing chemical or biological agents.”
Fusion reaction – animation
Dailymotion: Nuclear fusion
“Nuclear fusion is the joining (or fusing) of the nuclei of two atoms to form a single heavier atom. At extremely high temperatures – in the range of tens of millions of degrees – the nuclei of isotopes of hydrogen (and some other light elements) can readily combine to form heavier elements and in the process release considerable energy.
For fusion to occur, the electrostatic repulsion between the atoms must be overcome. Creating these conditions is one of the major problems in triggering a fusion reaction.”
Animation: Fission reaction
Dailymotion: Fission reaction (“Fission”)
“In nuclear fission, a heavy atomic nucleus, such as that of uranium or plutonium, will break up into two lighter nuclei. In the fission process, a large quantity of energy is released, radioactive products are formed, and several neutrons are emitted.
The released neutrons can also induce fission in a nearby nucleus of fissionable material and release more neutrons that can repeat the sequence, causing a chain reaction.”
Animation: 3-D model of Fat Man
Dailymotion: Fat Man was used in the bombing of Nagasaki (“Fatman_vr”)
“The initial design for the plutonium bomb was also based on using a simple gun design (known as the “Thin Man”) like the uranium bomb. As the plutonium was produced in the nuclear reactors at Hanford, Washington, it was discovered that the plutonium was not as pure as the initial samples from Lawrence’s Radiation Laboratory. The plutonium contained amounts of plutonium 240, an isotope with a rapid spontaneous fission rate. This necessitated that a different type of bomb be designed. A gun-type bomb would not be fast enough to work. Before the bomb could be assembled, a few stray neutrons would have been emitted from the spontaneous fissions, and these would start a premature chain reaction, leading to a great reduction in the energy released.
Seth Neddermeyer, a scientist at Los Alamos, developed the idea of using explosive charges to compress a sphere of plutonium very rapidly to a density sufficient to make it go critical and produce a nuclear explosion.”
Animation: 3-D model of Little Boy
Dailymotion: Little Boy the bomb that was used in the bombing of Hiroshima (“Littleboy_vr”)
“In essence, the Little Boy design consisted of a gun that fired one mass of uranium 235 at another mass of uranium 235, thus creating a supercritical mass. A crucial requirement was that the pieces be brought together in a time shorter than the time between spontaneous fissions. Once the two pieces of uranium are brought together, the initiator introduces a burst of neutrons and the chain reaction begins, continuing until the energy released becomes so great that the bomb simply blows itself apart.”
Image from the video
The only secret about nuclear weapons is that there is no secret
When journalist Howard Morland wrote an article explaining how an “H-Bomb” is made, the US Government took him to court. The plates were seized to prevent publication, because US officials claimed American security would be jeopardized if classified details on such an explosive topic were revealed. But Morland won his case without even going to the Supreme Court by showing that all the vital information was available in the Encyclopedia Americana — in an item written by Dr. Edward Teller, the “Father of the H-Bomb”. This picture, taken on the steps of the Supreme Court, shows Morland holding a cut-away model of an H-bomb, with its plutonium trigger (the small black globe at the top). Morland believes that the only secret about nuclear weapons is that there are no secrets. He thinks it is a greater threat to global security to suppose there are secrets when there aren’t, than to discuss how the bombs are actually made, because such false beliefs contribute to a false sense of security and an atmosphere of complacency.
Photo by Robert Del Tredici from his book entitled
At Work In The Fields Of The Bomb (Harper and Row, 1987)
How To Make an H-Bomb (or Thermonuclear bomb)
Howard Morland wrote a magazine article explaining how an “H-Bomb” — or “thermonuclear bomb” — is made, using only publicly available information. In the photo, he is standing on the steps of the US Supreme Court holding a cut-away model of the H-bomb.
An H-bomb is a three-stage weapon: fission, fusion, and then fission again. The first stage, called the “trigger” (the black ball at the top), is a small plutonium bomb similar to the one dropped on Nagasaki in 1945. The energy release at this stage is mainly due to nuclear fission — because the atoms of plutonium are split. Tritium is often added to the centre of the plutonium core to “boost” the fission explosion with some additional fusion energy. Boosted or not, however, the only importance of this first-stage explosion is to irradiate and heat the material in the central column to 100 million degrees celsius so that a much more powerful fusion reaction can be started there.
The second stage explosion is due to nuclear fusion in the central column. The main fusion reaction involves concentrated deuterium and tritium (both heavy isotopes of hydrogen) — which become spontaneously available when neutrons from the first stage explosion bombard a solid material called “lithium deuteride” located in the central column. When this hydrogen-rich mix is heated to 100 million degrees, the deuterium and tritium atoms “fuse” together, releasing enormous amounts of energy. This is the “H” or “thermonuclear” part of the bomb.
Then comes the third stage. The fusion reaction gives off an incredible burst of extremely powerful neutrons — so powerful that they can split or “fission” atoms of uranium-238 (called “depleted uranium”) — which is impossible at lower energy levels. This third stage more than doubles the power of the explosion, and produces most of the radioactive fallout from the weapon.
Unlike fission bombs, which rely only on nuclear fission, and which can achieve explosions equivalent to thousands of tons of TNT (“kilotons”), the power of an H-bomb or thermonuclear weapon has no practical limit — it can be made as powerful as you want, by adding more deuterium/tritium to the second stage. Most H-bombs are measured in “megatons” (equivalent to the explosive power of MILLIONS of tons of TNT — hundreds of times, or even a thousand times more powerful than a fission bomb).
American nuclear arsenal
This field full of ceramic cones represents, in miniature, the 25 000 warheads of the american nuclear arsenal. Plutonium is the principal nuclear explosive in most of these warheads. One of the greatest risks in using plutonium as a civilian nuclear fuel is the relative ease with which some of it could be stolen. Plutonium can be used — by anyone who gets their hands on it — to make nuclear weapons.
Photo by Robert Del Tredici from his book entitled At Work In The Fields Of The Bomb (Harper and Row, 1987)
Glass ball model of plutonium
This glass ball, 3.2 inches across, is the exact size of the plutonium core in the bomb that exploded over Nagasaki on August 9 1945 with a force equivalent to 22 thousand tons of TNT.
Photo by Robert Del Tredici
from his book entitled
At Work In The Fields Of The Bomb
(Harper and Row, 1987)
http://www.ccnr.org/breeding_ana.html (Canadian Coalition for Nuclear Responsibility)
This is a simple diagram illustrating an example of nuclear fission. A U-235 nucleus captures and absorbs a neutron, turning the nucleus into a U-236 atom. The U-236 atom experiences fission into Ba-141, Kr-92, three neutrons, and energy.
Fastfission, public domain
Caption: When neutrons are bombarded against uanium-235, the uranium-235 nucleus absorbs a neutron to be a uranium-236 and it splits into two fragments of almost equal masses with emitting some neutrons simultaneously and evolving a huge amount of energy larger than 200 MeV. This is nothing but one of the examples of fission of uranium-235. It does not always split into Ba and Kr but usually into two fragments with almost equal masses. The number of emitted neutrons is also not always constant but it distributes over one to several. Then the emitted energy is not always constant but is almost 200 MeV.
The US Government’s Usage of Atomic Bombs — Domestic — WTC
By Ed Ward, MD
In 1993, Joe Vialls exposes some facts about single explosions that were very similar to the 2001 WTC bombing. [..]
http://neworleans.media.indypgh.org/uploads/2006/09/blu82b-iz.jp URL: http://neworleans.indymedia.org/news/2006/09/8818.php Caption: Rare picture of damage from 6.3 tons of explosive from BLU-82
Another crater 22 feet wide and 5 feet deep is noted in the article Bali Micro Nuke – Lack of Radiation Confuses Experts. Within 48 hours the Bali government found traces of C4 explosive. Next came the revised explanation of explosives on top of gas containers. After that failed to explain noted facts, the next theory was explosives with napalm. The final explanation from London quoted a reliable source that an IRA style bomb mixture was used. Still, there were significant problems with the story as the IRA had detonated 1,000 pounds of the mixture and there was no crater produced. The US bomb, BLU-82 – used for clearing helicopter landing zones in the jungles of Vietnam – contains 6.3 tons of high grade military explosive with an aluminum additive for increased heat, but does not create a crater. The 1/4 inch steel encased explosive is parachuted to its target and detonated 1 to 2 feet above ground. Approximately 40 people close enough to be vaporized simply vanished without a trace. Insights on Israel’s .01 kt Dimona nuke are also related in this article. According to the information presented, the bomb uses highly enriched Plutonium 239, 99.78% pure, and only emits alpha radiation which is invisible to most Geiger counters.
Israel’s nuclear arsenal
Dimona nuclear reactor – Vanunu exposes
‘Vanunu gave the “Sunday Times” a detailed description – 60 photos he secretly shot. We took that information and from that it was possible to learn about the nuclear compound. We took all 60 photos from different parts of the compound, composed it with the information Vanunu gave, processed through computerized simulation, to give a never before seen 3D tour of Israel’s nuclear facilities.
Let us watch.
Only from space can you take pictures of Israel’s top secret site. No plane is allowed within this airspace. Only one man’s testimony – Mordechai Vanunu – revealed what is going on within this row of buildings surrounded by palms, “The row of institutes” as it is referred to. This is Institute No. 1, Dimona’s symbol, the 20 meters high, nuclear reactor’s dome.
Until now only seen from afar, Vanunu took us inside, into the reactor.
A heavy water reactor built in the 50s by the French, declared capacity of 24 MW.
And this is Vanunu’s first revealed secret:
The reactor’s capacity is three – possibly even five times larger than assumed until now.
This reactor produces 40 kg of plutonium a year, enough to build 10 atom bombs.
Adjacent to the reactor is Institute No. 3. In here, the fuel rods powering the reactor are produced together with lithium 6, another ingredient of the bomb.
This is Institute No. 5, here the fuel rods are coated with aluminium.
Institute No. 6 is the power station of the compound.
The lab is in Institute No. 8 and inside is another secret Vanunu revealed:
this is where Israel produces enriched uranium. Like plutonium, it can serve as fissionable material for the bomb. The uranium is produced through gas centrifuges, just like the Iranians are now trying to produce.
By the size of the building, it appears that the amount of uranium produced here is insignificant.
Enriched uranium is also produced in Institute No. 9 using laser – an Israeli unique patent.
Institute No. 10 produces depleted uranium, an important component in the production of armor piercing shells.
Institute No. 4 handles the radioactive waste, prior to being disposed. And this long two story building, with no windows, is Dimona’s big secret – Institute No. 2.
Beneath the two innocent looking floors, hidden underground, are six additional floors.
Vanunu showed the world what no satellite could see. Here Israel set up a plutonium separationf facility, with one goal – manufacturing atomic bombs.
In the 60s, American inspectors visited the first floor. They saw the restaurant and the offices. A special wall was constructed, hiding the elevators leading to the underground levels.
Back outside, trucks bring in the processed uranium rods. Through the large doors, a crane grasps the rods and lowers them to the big workspace, 4 floors below.
The rods are dipped in nitrous acid tanks, cooked for about 30 hours, and then a system of pipes draws the water containing the uranium and plutonium.
Through a chemical process, the materials are separated and then baked in an oven, producing a small 130 gram plutonium ball, 1.7 kg a week. 4 kg and it’s a bomb. Just like this model shot by Vanunu.
The process can be viewed from level 2. A balcony was built for distinguished guests. Nicknamed Golda’s Balcony.
And that’s the control room as shot by Vanunu. Only 150 employees are authorized to enter it. Visits are limited to the prime minister, the minister of defense, and a small group of confidants. Equipped with a hidden camera, Vanunu walked about Institute No. 2 and took pictures of the different sections. Not only plutonium is produced here, at level 4, Vanunu revealed the production of tritium used in the production of thermo-nuclear bombs, which are more powerful than ordinary atom bombs.
Two other essential materials for the bomb are produced here: lithium and deuterium. All these ingredients are taken to level 5, to Unit MD2 – Metal Department 2, where they are assembled into a bomb.
One level down is a recreation room, where Vanunu shot what experts identified as a model of an Israeli thermo-nuclear bomb, 10 times more powerful than the bomb dropped on Hiroshima.
Experts that analyzed Vanunu’s testimony, determined that by the 80s, Israel had produced 100-200 atom bombs.
This ranks Israel as the 6th or even 5th nuclear power in the world.
This presentation was based solely on data delivered by Vanunu to the “Sunday Times”. ‘
Still from the video
Closeup of the Dimona nuclear plant
The Dimona Reactor Dome. (Courtesy of Mordechai Vanunu).
Mockup of a Dimona bomb. (Photo courtesy of Mordechai Vanunu)
Two Mordechai Vanunu photos.
Control room of the Machon 2 plutonium separation plant. (Photo courtesy of Mordechai Vanunu)
Revealed: the secrets of Israel’s nuclear arsenal
http://upload.wikimedia.org/wikipedia/en/4/49/Vanuunu-Article.jpg URL: http://en.wikipedia.org/wiki/Nuclear_weapons_and_Israel Caption: On 5 October 1986, the British newspaper The Sunday Times ran Mordechai Vanunu’s story on its front page under the headline: “Revealed: the secrets of Israel’s nuclear arsenal”
Sunday October 5, 1986: Headline: Revealed – the secrets of Israel’s nuclear arsenal/ Atomic technician Mordechai Vanunu reveals secret weapons production
THE SECRETS of a subterranean factory engaged in the manufacture of Israeli nuclear weapons have been uncovered by The Sunday Times Insight team.
Hidden beneath the Negev desert, the factory has been producing atomic warheads for the last 20 years. Now it has almost certainly begun manufacturing thermo-nuclear weapons, with yields big enough to destroy entire cities.
Information about Israel’s capacity to manufacture the bomb come from the testimony of Mordechai Vanunu, a 31-year-old Israeli who worked as a nuclear technician for nearly 10 years in Machon 2 – a top secret, underground bunker built to provide the vital components necessary for weapons production at Dimona, the Israeli nuclear research establishment.
Vanunu’s evidence has surprised nuclear weapons experts who were approached by Insight to verify its accuracy because it shows that Israel does not just have the atom bomb – which has been long suspected – but that it has become a major nuclear power.
Vanunu’s testimony and pictures, which have been scrutinised by nuclear experts on both sides of the Atlantic, show that Israel has developed the sophisticated and highly classified techniques needed to build up a formidable nuclear arsenal. They confirm that:
Israel now ranks as the world’s sixth most powerful nuclear power, afterAmerica, the Soviet Union, Britain France and China – with an arsenal far greater than than those other countries, such as India, Pakistan and South Africa, which have also been suspected of developing nuclear weapons.
It has possessed its secret weapons factory for more than two decades, hiding its plutonium extraction processes from spy satellites and independent inspections during the 1960s by burying it beneath an innocuous, little used building.
The plant is equipped with French plutonium extracting technology, which transformed Dimona from a civilian research establishment to a bomb production facility. Plutonium production rates amount to 40 kilograms a year, enough to build 10 bombs. In the past six years Israel has added further equipment to make components for thermo-nuclear devices.
The 26 megawatt reactor, also built by the French, has been expanded and is probably now operating at 150 megawatts to allow it to extract more plutonium. An ingenious cooling system disguises the output.
The nuclear scientists consulted by The Sunday Times are convinced by Vanunu’s evidence. They calculate that at least 100 and as many as 200 nuclear weapons of varying destructive power have been assembled – 10 times the previously estimated strength of Israel’s nuclear arsenal.
One of the pictures Vanunu took
http://www.peaceheroes.com/images/Dimonacntrlslg.jpg URL: http://www.peaceheroes.com/MordecaiVanunu/controlroom.htm Caption: This is a photo of a plutonium separation plant’s control room, with equipment recognizable by nuclear scientists as part of a nuclear weapons production facility. Dimona Nuclear Weapons Facility Machon 2, Negrev Desert, Israel (courtesy M. Vanunu)
Israeli nuclear ‘power’ exposed
Sunday, 16 March, 2003, 01:47 GMT by Olenka Frankiel
http://newsimg.bbc.co.uk/media/images/38942000/jpg/_38942715_315vanunu.jpg URL: http://news.bbc.co.uk/2/hi/programmes/correspondent/2841377.stm Caption: Israel has enforced Vanunu’s silence for 16 years
Mordechai Vanunu, Israel’s nuclear whistleblower, was jailed in 1986 for publishing photographs of Israel’s nuclear bomb factory at Dimona. Olenka Frenkiel reveals the extent of Israel’s nuclear gagging.
Vanunu has spent 17 years in jail, 11 of which were in a minute solitary confinement cell – and he has just had his appeal for parole denied.
He will stay in jail until 2004, when his term is expected to end.
Caption: Revelations hit the press in October 1986 Image: http://news.bbc.co.uk/media/images/38952000/jpg/_38952439_150sunday_times.jpg URL: http://news.bbc.co.uk/2/hi/programmes/correspondent/2841377.stm
Sunday Times journalist Peter Hounam heard rumours in 1986 that an Israeli whistleblower was offering proof of what the world had long suspected.
Vanunu was that whistleblower.
His revelations confirmed that Israel was building advanced nuclear weapons
After the Sunday Times published this scoop, Vanunu was lured to Italy and kidnapped by Mossad agents and illegally smuggled back to Israel.
He was tried in secret and convicted of treason and spying.
Security chief exposed
In court, at his parole hearing, Avigdor Feldman, Vanunu’s lawyer, argued that his client had no more secrets and should be freed.
But the prosecutor had a new argument: the imminent war with Iraq.
After the hearing Mr Feldman told Correspondent: “The prosecutor said that if Vanunu were released, the Americans would probably leave Iraq and go after Israel and Israel’s nuclear weapons – which I found extremely ridiculous.”
The real force blocking Vanunu’s release is a man who was known only as “Y”.
In 2001, “Y” was exposed as Yehiyel Horev and it is said that the only thing he fears is publicity.
Mr Horev is the head of Israel’s most powerful intelligence service, dealing with nuclear and military secrets.
http://news.bbc.co.uk/media/images/38953000/jpg/_38953133_150yehiyel_horev.jpg URL: http://news.bbc.co.uk/2/hi/programmes/correspondent/2841377.stm Caption: Yehiyel Horev unmasked, here, for the first time
His accountability has only been to the many prime ministers he has watched come and go in the 16 years he has built his power base.
He has been likened to the head of the FBI, J Edgar Hoover – an autocrat out of control.
Ronen Bergman, security correspondent for one of Israel’s leading newspapers – Yediot Ahronoth – says: “Horev is a grave danger to Israeli democracy.
“He operates with no law, no real scrutiny and no monitoring by the Israeli parliament.
“Horev was afraid that veterans of the Israeli intelligence and the Israeli nuclear effort would try to maintain their footprint in the history of Israel and tell their story.
“He wanted to frighten them.”
Acting with impunity
Israel never confirms or denies claims that it has nuclear, chemical and biological weapons.
The country positions itself outside international treaties, which would make it subject to inspection.
Uzi Even – Dimona should be shut down
For 40 years, most Israelis have been content with this policy – known as “nuclear ambiguity”.
But there are some in Israel who argue this policy has had its day.
They say the costs of such secrecy to Israeli democracy are too great.
Uzi Even, was a young scientist working, in the 60s, at Dimona – Israel’s nuclear reactor – as did Vanunu.
Today, Mr Even says it should be shut down.
Forty-year-old reactors tend to have accidents and he believes that Dimona, which is beyond the reach of the Israeli parliament, needs to be brought into a system of accountability and public scrutiny.
Mr Even explained: “You should have an outside watchdog.
“The secrecy more or less created an extra- territorial area in Israel where standard procedures of safety monitoring are not implemented.
“So worker safety, environmental questions and industrial safety procedures, are not covered, and there are thousands of people working there.”
Nothing illustrates this better than the sensitive issue of Dimona’s cancer victims.
In an Israeli documentary in 2002, Dimona workers said accidents had been routine.
They spoke of explosions, fires and liquid and toxic gas leaks that they had to clean, often without protection.
http://news.bbc.co.uk/media/images/38958000/jpg/_38958193_150reactor.jpg URL: http://news.bbc.co.uk/2/hi/programmes/correspondent/2841377.stm Caption: Accidents were ‘routine’ at Dimona
The authorities denied they had worked with radioactive materials.
They have refused to compensate them or their families for their years of loyal service.
Because of the strict secrecy rules they were even unable to fight for their rights.
When Correspondent approached one of the workers, who was dying of cancer, he refused to be interviewed – but with some regret.
Unaware he was being filmed, he said: “I wanted to talk to you but I have been silenced.
“They came from intelligence and told me not to talk.
“They said I would be like Vanunu.”
Vanunu has another year in jail.
When his sentence is finished he hopes to emigrate to America.
But Mr Horev has clearly let it be known he never intends to let Vanunu leave Israel.
http://upload.wikimedia.org/wikipedia/en/c/c9/Dimona11.11.68.jpg URL: http://en.wikipedia.org/wiki/Nuclear_weapons_and_Israel Caption: Completed Dimona complex as seen by US Corona satellite on November 11, 1968
Caption: Mordechai Vanunu’s photograph of a Negev Nuclear Research Center glove box containing nuclear materials in a model bomb assembly, one of about 60 photographs he later gave to the British press. http://upload.wikimedia.org/wikipedia/en/2/29/Vanunu-glove-box-bomb-components.jpg URL: http://en.wikipedia.org/wiki/Nuclear_weapons_and_Israel
The Third Temple’s Holy Of Holies: Israel’s Nuclear Weapons
by Warner D. Farr, LTC, U.S. Army September 1999
This paper is a history of the Israeli nuclear weapons program drawn from a review of unclassified sources. Israel began its search for nuclear weapons at the inception of the state in 1948. As payment for Israeli participation in the Suez Crisis of 1956, France provided nuclear expertise and constructed a reactor complex for Israel at Dimona capable of large-scale plutonium production and reprocessing. The United States discovered the facility by 1958 and it was a subject of continual discussions between American presidents and Israeli prime ministers. Israel used delay and deception to at first keep the United States at bay, and later used the nuclear option as a bargaining chip for a consistent American conventional arms supply. After French disengagement in the early 1960s, Israel progressed on its own, including through several covert operations, to project completion. Before the 1967 Six-Day War, they felt their nuclear facility threatened and reportedly assembled several nuclear devices. By the 1973 Yom Kippur War Israel had a number of sophisticated nuclear bombs, deployed them, and considered using them. The Arabs may have limited their war aims because of their knowledge of the Israeli nuclear weapons. Israel has most probably conducted several nuclear bomb tests. They have continued to modernize and vertically proliferate and are now one of the world’s larger nuclear powers. Using “bomb in the basement” nuclear opacity, Israel has been able to use its arsenal as a deterrent to the Arab world while not technically violating American nonproliferation requirements.
Mini-nukes and micro-nukes
According to brave activist, Howard Morland, in his article The Holocaust Bomb: a Question of Time, second generation atomic bombs got their start in 1950 and came to fruition in 1956 with Eisenhower’s announcement of a 95% clean bomb. In 1958 the Mk-41C was tested for a 9.3 Megaton yield, 4.8% of the energy was from fission with 95.2% from fusion. Less radioactive (more fusion and less fission energy) or semi-clean H-bombs were known then and were used for testing purposes only. The more powerful, mostly fission bombs were deployed for usage in a cognitive effort to produce maximum destruction on ‘enemies’ for generations and no forethought of the worldwide consequences. Among various other types of hydrogen bomb warheads, the W54 nuke was developed in 1961. The W54 was a micro-nuke that weighed 51 pounds and could be fired from a slightly modified ordinary bazooka. Different versions of the W54 ranged from .01 kt to 1 kt yield. Between the mid 1950’s and the mid 70’s both types (large yield dirty and small yield clean), of 2nd generation H-bombs were refined.
Focused nuclear explosions were envisioned in 1959 as a possible concept for propulsion of the spacecraft Orion. The mere directing of the yield was obviously known prior to 1959. Samuel Cohen has stated that a low yield neutron bomb may be tailored to direct yield and proposed the concept more than 35 years ago. An underground detonation causes shaping of the direction of yield as well.
Nine nuclear and chemical weapons sites in Israel––according to this Hezbollah video
VIDEO: Nine Israeli Nuclear And Chemical Sites مواقع المفاعلات النووية الإسرائيلية ArchiveOrg
Medium Atomic Demolition Munitions (MADM)
Caption: scientists displaying the warhead (left) and packing container for the Medium Atomic Demolition Munition (MADM), a low-yield (1- to 15-kiloton) nuclear land mine designed to be deployed behind enemy lines and destroy tunnels, bridges, dams, and disrupt enemy troop movements. The entire unit (including warhead) weighed less than 400 pounds and was deployed from 1965 to 1986.
Another view of the MADM, showing (from left) the packing container, warhead, code-decoder unit, and firing unit.
The carrying case for the W54 Special Atomic Demolition Munition (SADM). The SADM had a yield of 0.01, or 0.02-1 kiloton and was operationally deployed between 1964 and 1988. The entire unit weighed less than 163 pounds (74 kilograms).
Images: Credit: Department of Defense (courtesy Natural Resources Defense Council)
BBC documentary on Vanunu – Israel’s Terror WMD Facilities
Youtube: “Vanunu told the world that Israel had developed between one hundred to two hundred atomic bombs, and had gone on to develop neutron bombs and thermonuclear weapons – enough to destroy the entire Middle East, and nobody has done anything about it since.”
“Today proliferation experts report Israel has the sixth largest nuclear arsenal with small tactical nuclear weapons, nuclear land mines as well as medium range nuclear missiles launchable from air land and sea …”
Israel and the Schiphol plane crash
Dirty and clean weapons
“Dirty” and “Clean” Weapons
Whether to make a fission-fusion weapon into a fission-fusion-fission weapon is one of the most basic design issues. A fission-fusion weapon uses an inert (or non-fissionable) tamper and will obtain most of its yield from the fusion reaction directly. A fission-fusion-fission weapon will obtain at least half of its yield (and often far more) from the fusion neutron induced fission of a fissionable tamper.
The basic advantage of a fission-fusion-fission weapon is that energy is extracted from a tamper which is otherwise deadweight as far as energy production in concerned. The tamper has to be there, so a lighter weapon for a given yield (or a more powerful weapon for the same weight) can be obtained without varying any other design factors. Since it is possible to do this at virtually no added cost or other penalty, compared to an inert material like lead, by using natural or depleted uranium or thorium there is basically no reason not to do it if the designer is simply interested in making big explosions.
Fission of course produces radioactive debris – fallout. Fallout can be reduced by using a material that does not become highly radioactive when bombarded by neutrons (like lead or tungsten). This requires a heavier and more expensive weapon to produce a given yield, but is also considerably reduces the short and long term contamination associated with that yield.
This is not to say that the weapon is “clean” in any commonsense meaning of the term. Neutrons escaping the weapon can still produce biohazardous carbon-14 through nitrogen capture in the air. The primary and spark plug may still contribute 10-20% fission, which for a multi-megaton weapon may still be a megaton or more of fission. Significant contamination may also occur from the “inert” tamper radioisotopes, and even from the unburned tritium produced in the fusion stage. Reducing these contributions to the lowest possible level is the realm of “minimum residual radiation” designs discussed further below.
During the fifties interest in both the US and USSR was given to developing basic design that had both clean and dirty variants. The basic design tried to minimize the essential fission yield by using a small fission primary, and spark plug sizes carefully chosen to meet ignition requirements for each stage, without being excessive (note that although only part of the spark plug will fission to ignite the fusion stage, the essentially complete fission of the remainder by fusion neutrons is inevitable). These weapons appear to have all been three-stage weapons to allow multi-megaton yields (even in the clean version) with a relatively small primary. The dirty version might simply replace the inert tamper of the tertiary with a fissionable one to boost yield.
The three-stage Bassoon and Bassoon Prime devices tested in Redwing Zuni (27 May 1956, 3.5 Mt, 15% fission) and Redwing Tewa (20 July 1956, 5 Mt, 87% fission) are US tests of this concept. Clearly though, the second test was not simply a copy of the first with a different tamper. The fusion yield dropped from 3 Mt to 0.65 Mt, and the device weight increased from 5500 kg to 7149 kg between the two tests. The inference can be made that the tertiary in the first used a large volume of relatively expensive (but light) Li-6D in a thin tamper, which was replaced by a heavier, cheaper tertiary using less fusion fuel, but a very thick fissionable tamper to capture as many neutrons as possible.
The 50 Mt three stage Tsar Bomba (King of Bombs) tested by the Soviet Union on 30 October 1961 was the largest and cleanest bomb ever tested, with 97% of its yield coming from fusion (fission yield approximately 1.5 Mt). Assuming a primary of 250 kt (to keep the fissile content relatively low for safety reasons), we might postulate secondary and tertiary stages of 3.5 Mt and 46 Mt respectively. This fusion stages would require 1700 kg of Li6D (at 50% fusion efficiency), and something like 250 kt of fission for reliable ignition. If the initial spark plug firings were 25% efficient, later fission would release another 750 kt – placing the total at 1.25 Mt (close enough to the claimed parameters to match within the limits of accuracy).
This was a design though for a 100-150 Mt weapon! A lead tamper was used in the tested device, which could have been replaced with U-238 for the dirty version (thankfully never tested!).
Minimum Residual Radiation (MRR or “Clean”) Designs
It has been pointed out elsewhere in this FAQ that ordinary fission-fusion- fission bombs (nominally 50% fission yield) are so dirty that they merit consideration as radiological weapons. Simply using a non-fissile tamper to reduce the fission yield to 5% or so helps considerably, but certainly does not result in an especially clean weapon by itself. If minimization of fallout and other sources of residual radiation is desired then considerably more effort needs to be put into design.
Minimum residual radiation designs are especially important for “peaceful nuclear explosions” (PNEs). If a nuclear explosive is to be useful for any civilian purpose, all sources of residual radiation must be reduced to the absolute lowest levels technologically possible. This means elimination of neutron activation of bomb components, of materials outside the bomb, and reducing the fissile content to the smallest possible level. It may also be desirable to minimize the use of relatively hazardous materials like plutonium.
The problems of minimizing fissile yield and eliminating neutron activation are the most important. Clearly any MRR, even a small one, must be primarily a fusion device. The “clean” devices tested in the fifties and early sixties were primarily high yield strategic three-stage systems. For most uses (even military ones) these weapons are not suitable. Developing smaller yields with a low fissile content requires considerable design sophistication – small light primaries so that the low yields still produce useful radiation fluxes and high-burnup secondary designs to give a good fusion output.
Minimizing neutron activation form the abundant fusion neutrons is a serious problem since many materials inside and outside the bomb can produce hazardous activation products. The best way of avoiding this is too prevent the neutrons from getting far from the secondary. This requires using an efficient clean neutron absorber, i.e. boron-10. Ideally this should be incorporated directly into the fuel or as a lining of the fuel capsule to prevent activation of the tamper. Boron shielding of the bomb case, and the primary may be useful also.
It may be feasible to eliminate the fissile spark plug of a MRR secondary by using a centrally located deuterium-tritium spark plug similar to the way ICF capsules are ignited. Fusion bombs unavoidably produce tritium as a by- product, which can be a nuisance in PNEs.
Despite efforts to minimize radiation releases, PNEs have largely been discredited as a cost-saving civilian technology. Generally speaking, MRR devices still produce excessive radiation levels by civilian standards making their use impractical.
MRRs may have military utility as a tactical weapon, since residual contamination is slight. Such weapons are more costly and have lower performance of course.
This leads to another reason why PNEs have lost their attractiveness – there is no way to make a PNE device unsuitable for weapons use. “Peaceful” use of nuclear explosives inherently provides opportunity to develop weapons technology. As the saying goes, “the only difference between a PNE and a bomb is the tail fins”.
http://nuclearweaponarchive.org/Nwfaq/Nfaq4-5.html – Nuclear Weapons Frequently Asked Questions Version 2.04: 20 February 1999 COPYRIGHT CAREY SUBLETTE
Low Yield Weapons
This represents one extreme of the weapon design spectrum – nuclear devices intend to make “small” explosions. Low yield in this context generally means yields much less than the 20 kts of a nominal fission weapon – say, 1-1000 tons. These are, of course, always very large compared to any other types of weapon of remotely similar size. They are small only in comparison to the potential capabilities of nuclear weapons.
The smallest nuclear weapons actually deployed have had yields around 10 tons (like the W54), and have been intended for short range tactical or nuclear demolition use (e.g. blowing up roads and bridges).
A low yield weapon can be made simply by taking an existing weapon and reducing its efficiency in some manner – like reducing the amount of explosive to create a weak implosion. But this likely result in a low-yield the weapon with unnecessarily high mass, volume, and cost.
A weapon designer will probably want to optimize a low yield weapon toward one of two design goals: minimizing its size or minimizing its cost (basically this means minimizing the fissile content of the device). Real weapons typically try to strike a balance between the two extremes.
A low yield minimum mass or volume weapon would use an efficient fissile material (plutonium or U-233), a low mass implosion system (i.e. a relatively weak one), and a thin beryllium reflector (thickness no more than the core radius). Since volume increases with the cube of the radius, a thick layer of anything (explosive or reflector) surrounding the fissile core will add much more mass than that of the core itself.
Referring to the Reflector Savings Table 188.8.131.52.2.2-3 we can see that for beryllium thicknesses of a few centimeters, the radius of a plutonium core is reduced by 40-60% of the reflector thickness. Since the density difference between these materials is on the order of 10:1, substantial mass savings can be achieved. At some point though increasing the thickness of the reflector begins to add more mass than it saves, this marks the point of minimum total mass for the reflector/core system.
In general, minimum mass and minimum volume designs closely resemble each other. The use of a hollow core adds negligibly to the overall volume.
At the low end of this yield range (tens of tons) simply inducing the delta -> alpha phase transition in a metastable plutonium alloy may provide sufficient reactivity insertion. In this case a classical implosion system is not even necessary, a variety of mechanisms could be used to produce the weak 10-20 kilobar shock required to collapse the crystal structure.
Since the fissile core would be lightly reflected, and weakly compressed, a relatively large amount of fissile material is required: perhaps 10 kg for even a very low yield bomb. The efficiency is of course extremely poor, and the cost relatively high.
The absolute minimum possible mass for a bomb is determined by the smallest critical mass that will produce a significant yield. Since the critical mass for alpha-phase plutonium is 10.5 kg, and an additional 20-25% of mass is needed to make a significant explosion, this implies 13 kg or so. A thin beryllium reflector will reduce this, but the necessary high explosive and packaging will add mass, so the true absolute minimum probably lies in the range of 10-15 kg.
The W54 warhead used in the Davy Crockett had a minimum mass of about 23 kg, and had yields ranging from 10 tons up to 1 kt in various mods (probably achieved by varying the fissile content). The warhead was basically egg-shaped with the minor axis of 27.3 cm and a major axis of 40 cm. The W-54 probably represents a near minimum diameter for a spherical implosion device (the U.S. has conducted tests of a 25.4 cm implosion system however).
The test devices for this design fired in Hardtack Phase II (shots Hamilton and Humboldt on 15 October and 29 October 1958) weighed only 16 kg, impressively close to the minimum mass estimated above. These devices were 28 cm by 30 cm, Humboldt used PBX-9404 as the explosive.
http://nuclearweaponarchive.org/Nwfaq/Nfaq4-5.html – Nuclear Weapons Frequently Asked Questions Version 2.04: 20 February 1999 COPYRIGHT CAREY SUBLETTE
Davy Crockett weapon – From Wikipedia: Davy Crockett
Caption: The Davy Crockett (shown here at the Aberdeen Proving Ground in Maryland in March 1961) was the smallest and lightest nuclear weapon ever deployed by the U.S. military. It was designed for use in Europe against Soviet troop formations.
The M-28 or M-29 Davy Crockett Weapon System(s) was a tactical nuclear recoilless gun for firing the M388 nuclear projectile that was deployed by the United States during the Cold War. Named after American soldier, congressman and folk hero Davy Crockett, it was one of the smallest nuclear weapon systems ever built. [..]
Img: http://upload.wikimedia.org/wikipedia/commons/thumb/f/f8/Recoilless_gun_155mm_Davy_Crockett3.jpg/170px-Recoilless_gun_155mm_Davy_Crockett3.jpg URL: http://en.wikipedia.org/wiki/Davy_Crockett_%28nuclear_device%29 Caption: A Davy Crockett casing preserved in the United States Army Ordnance Museum
The M-388 round used a version of the W54 warhead, a very small sub-kiloton fission device. The Mk-54 weighed about 51 lb (23 kg), with a selectable yield equivalent to 10 or 20 tons of TNT (very close to the minimum practical size and yield for a fission warhead). The complete round weighed 76 lb (34.5 kg). It was 31 in. (78.7 cm) long with a diameter of 11 in. (28 cm) at its widest point; a subcaliber piston at the back of the shell was inserted into the launcher’s barrel for firing
The World’s Smallest Nuke
VIDEO: The World’s Smallest Nuke Dailymotion
W54 – From Wikipedia: W54
The W54 was the smallest nuclear warhead deployed by the United States. It was a very compact implosion-type nuclear weapon design, designed for tactical use and had a very low yield for a nuclear weapon. [..]
Img: http://upload.wikimedia.org/wikipedia/commons/thumb/d/d9/Davy_Crockett_bomb.jpg/220px-Davy_Crockett_bomb.jpg URL: http://en.wikipedia.org/wiki/W54 Caption:The W54 nuclear warhead was used in the man-portable M-388 Davy Crockett projectile. The unusually small size of the warhead is apparent
There were four distinct models of the basic W54 design used, each with different yield, but the same basic design. These were:
- Mk-54 (Davy Crockett) — 10 or 20 ton yield, Davy Crockett artillery warhead
- Mk-54 (SADM) — variable yield 10 ton to 1 kiloton, Special Atomic Demolition Munition device
- W-54 — 250 ton yield, warhead for AIM-26 Falcon air to air missile
- W72 — 600 ton yield, rebuilt W-54 (Falcon warhead) for AGM-62 Walleye
All four variants share the same basic core: a nuclear system which is 10.75 inches diameter (270 mm), about 15.7 inches long (400 mm), and weighs around or slightly over 50 pounds (23 kg). [..]
Though small compared to most other nuclear weapons, whose yields are usually measured in the thousands of tons of TNT (kilotons), in human terms they are still extremely large. By comparison, the smallest yield version of the W54 (10 tons) is two to four times as powerful as the 1995 Oklahoma City bombing, making the 250 ton version 50 to 100 times as powerful. [..]
The W54 style warhead was known to be used on the M-388 Davy Crockett, a tactical nuclear recoilless rifle projectile that was deployed by the United States during the Cold War.
The W54 is small enough to be deployed as a SADM (Special Atomic Demolition Munition) or so called “Backpack Nuke”. It was the closest thing the U.S. is known to have to developed to a so-called “suitcase bomb”.
Img: http://upload.wikimedia.org/wikipedia/commons/2/21/SADM%28cropped%29.jpg URL: http://en.wikipedia.org/wiki/W54 Caption: The W54 would have fit into the Special Atomic Demolition Munition (“Backpack Nuke”) casing
The W54 was tested for use in a U.S. Navy SEALs project that was demonstrated as feasible in the mid-to-late 1960s, designed to attack a harbor or other strategic location that could be accessed from the sea. The SEALs version would be delivered into water by parachute along with a two man team, then floated to the target, set in place and armed by hand.
Thermonuclear devices – Wikipedia Nuclear Weapon Design
Two-stage thermonuclear weapons are essentially a chain of fission-boosted fusion weapons [..] usually with only two stages in the chain. The second stage, called the “secondary,” is imploded by x-ray energy from the first stage, called the “primary.” This radiation implosion is much more effective than the high-explosive implosion of the primary. Consequently, the secondary can be many times more powerful than the primary, without being bigger. The secondary can be designed to maximize fusion energy release, but in most designs fusion is employed only to drive or enhance fission, as it is in the primary. More stages could be added, but the result would be a multi-megaton weapon too powerful to serve any plausible purpose. [..]
The term thermonuclear refers to the high temperatures required to initiate fusion. It ignores the equally important factor of pressure, which was considered secret at the time the term became current. [..]
Pure fission or fusion-boosted fission weapons can be made to yield hundreds of kilotons, at great expense in fissile material and tritium, but by far the most efficient way to increase nuclear weapon yield beyond ten or so kilotons is to tack on a second independent stage, called a secondary.
In the 1940s, bomb designers at Los Alamos thought the secondary would be a canister of deuterium in liquified or hydride form. [..] Mathematical simulations showed it wouldn’t work, even with large amounts of prohibitively expensive tritium added in.
The entire fusion fuel canister would need to be enveloped by fission energy, to both compress and heat it, as with the booster charge in a boosted primary. The design breakthrough came in January 1951, when Edward Teller and Stanisław Ulam invented radiation implosion. [..]
In radiation implosion, the burst of X-ray energy coming from an exploding primary is captured and contained within an opaque-walled radiation channel which surrounds the nuclear energy components of the secondary. The radiation quickly turns the plastic foam that had been filling the channel into a plasma which is mostly transparent to X-rays, and the radiation is absorbed in the outermost layers of the pusher/tamper surrounding the secondary, which ablates and applies a massive force [..] causing the fusion fuel capsule to implode much like the pit of the primary. As the secondary implodes a fissile “spark plug” at its center ignites and provides heat which enables the fusion fuel to ignite as well. The fission and fusion chain reactions exchange neutrons with each other and boost the efficiency of both reactions. The greater implosive force, enhanced efficiency of the fissile “spark plug” due to boosting via fusion neutrons, and the fusion explosion itself provides significantly greater explosive yield from the secondary despite often not being much larger than the primary.
Clean bombs – From Wikipedia: Nuclear Weapon Design
[..] In response to the public alarm over fallout, an effort was made to design a clean multi-megaton weapon, relying almost entirely on fusion. Since the energy produced by fission is essentially free, using the vital tamper as a source of extra energy, the clean bomb needed to be much larger for the same yield. For the only time, a third stage, called the tertiary, was added, using the secondary as its primary. The device was called Bassoon. It was tested as the Zuni shot of Operation Redwing, at Bikini on May 28, 1956. With all the uranium in Bassoon replaced with a substitute material such as lead, its yield was 3.5 megatons, 85% fusion and only 15% fission. The records for devices that produced the highest proportion of their yield via fusion only reactions, known in the public domain are, the Redwing Navajo test at 95% Fusion, The Hardtack Poplar test at 95.2% & the 97% Tsar bomba.
Tsar Bomba – from Wikipedia: Tsar Bomba
Tsar Bomba (Russian: Царь-бомба) is the nickname for the AN602 hydrogen bomb, the most powerful nuclear weapon ever detonated. Also known as Kuz`kina Mat` (Russian: Кузькина мать, Kuzma’s mother).
Developed by the Soviet Union, the bomb was originally designed to have a yield of about 100 megatons of TNT (420 PJ); however, the bomb yield was reduced to 50 megatons—one quarter of the estimated yield of the 1883 eruption of Krakatoa—in order to reduce nuclear fallout. This attempt was successful, as it was one of the cleanest (relative to its yield) atomic bombs ever detonated. Only one bomb of this type was ever built and it was tested on October 30, 1961, in the Novaya Zemlya archipelago. [..]
The tsar was a three-stage Teller–Ulam design hydrogen bomb with a yield of 50 megatons (Mt). This is equivalent to 1,400 times the combined power of the two nuclear explosives used in World War II (Little Boy (13–18 kilotons) and Fat Man (21 kilotons), the bombs that destroyed Hiroshima and Nagasaki), or 10 times the combined power of all the explosives used in WWII. A three-stage H-bomb uses a fission bomb primary to compress a thermonuclear secondary, as in most H-bombs, and then uses energy from the resulting explosion to compress a much larger additional thermonuclear stage. However, there is evidence that the Tsar Bomba had a number of third stages rather than a single very large one.
The initial three-stage design was capable of approximately 100 Mt, but would have caused too much radioactive fallout. To limit fallout, the third stage and possibly the second stage had a lead tamper instead of a uranium-238 fusion tamper (which greatly amplifies the reaction by fissioning uranium atoms with fast neutrons from fusion reaction). This eliminated fast fission by the fusion-stage neutrons, so that approximately 97% of the total energy resulted from fusion alone (as such, it was one of the “cleanest” nuclear bombs ever created, generating a very low amount of fallout relative to its yield). There was a strong incentive for this modification since most of the fallout from a test of the bomb would fall on populated Soviet territory.
http://upload.wikimedia.org/wikipedia/en/c/c9/Tsar_photo11.jpg URL: http://en.wikipedia.org/wiki/Tsar_bomba Caption: The Tsar Bomba mushroom cloud
Tsar Bomb – The King of the bombs
http://www.atomcentral.com/tsar/images/tsar_bomba.jpg URL: http://www.atomcentral.com/tsar.html Caption: Tsar Bomba – King of the Bombs. On October 23, 1961, Soviet pilot A. E. Durnovtsev guides his Tu-95 Bomber towards the Arctic Sea above Novaya Zemlya Island. This day will make atomic history, not as an advancement in nuclear science, but rather as a statement of intimidation by the Soviet Union to the United States in those tense days now known as The Cold War.
The bomber is carrying a secret cargo that will soon make the world take notice of Russia as a serious nuclear threat to the survial of mankind. For on this day a nuclear weapon rides into history as the largest thermonuclear bomb ever constructed and detonated named, “Tsar Bomba…King of the Bombs.”
Teller-Ulam design – from Wikipedia: Teller-Ulam design
The Teller–Ulam design is the nuclear weapon design concept used in most of the world’s nuclear weapons. [..] It is named for its two chief contributors, Edward Teller and Stanisław Ulam, who developed it in 1951 for the United States. It was first used in multi-megaton-range thermonuclear weapons. As it is also the most efficient design concept for small nuclear weapons, today virtually all the nuclear weapons deployed by the five major nuclear-armed nations use the Teller–Ulam design.
Its essential features, which officially remained secret for nearly three decades, are: 1) separation of stages into a triggering “primary” explosive and a much more powerful “secondary” explosive, 2) compression of the secondary by X-rays coming from nuclear fission in the primary, a process called the “radiation implosion” of the secondary, and 3) heating of the secondary, after cold compression, by a second fission explosion inside the secondary.
The radiation implosion mechanism is a heat engine exploiting the temperature difference between the hot radiation channel, surrounding the secondary, and the relatively cool interior of the secondary. This temperature difference is briefly maintained by a massive heat barrier called the “pusher”. The pusher is also an implosion tamper, increasing and prolonging the compression of the secondary, and, if made of uranium, which it usually is, it undergoes fission by capturing the neutrons produced by fusion. In most Teller–Ulam weapons, fission of the pusher dominates the explosion and produces radioactive fission product fallout. [..]
The basic principle of the Teller–Ulam configuration is the idea that different parts of a thermonuclear weapon can be chained together in “stages”, with the detonation of each stage providing the energy to ignite the next stage. At a bare minimum, this implies a primary section which consists of a fission bomb (a “trigger”), and a secondary section which consists of fusion fuel. Because of the staged design, it is thought that a tertiary section, again of fusion fuel, could be added as well, based on the same principle of the secondary. The energy released by the primary compresses the secondary through the concept of “radiation implosion”, at which point it is heated and undergoes nuclear fusion. [..]
A simplified summary of the above explanation would be:
1. An implosion assembly type of fission bomb is exploded. This is the primary stage. If a small amount of deuterium/tritium gas is placed inside the primary’s core, it will be compressed during the explosion and a nuclear fusion reaction will occur; the released neutrons from this fusion reaction will induce further fission in the plutonium-239 or uranium-235 used in the primary stage. The use of fusion fuel to enhance the efficiency of a fission reaction is called boosting. Without boosting, a large portion of the fissile material will remain unreacted; the Little Boy and Fat Man bombs had an efficiency of only 1.4% and 14%, respectively, because they were unboosted.
2. Energy released in the primary stage is transferred to the secondary (or fusion) stage. The exact mechanism whereby this happens is unknown. This energy compresses the fusion fuel and sparkplug; the compressed sparkplug becomes critical and undergoes a fission chain reaction, further heating the compressed fusion fuel to a high enough temperature to induce fusion, and also supplying neutrons that react with lithium to create tritium for fusion. Generally, increasing the kinetic energy of gas molecules contained in a limited volume will increase both temperature and pressure (see gas laws).
3. The fusion fuel of the secondary stage may be surrounded by depleted uranium or natural uranium, whose U-238 is not fissile and cannot sustain a chain reaction, but which is fissionable when bombarded by the high-energy neutrons released by fusion in the secondary stage.
Actual designs of thermonuclear weapons may vary. For example, they may or may not use a boosted primary stage, use different types of fusion fuel, and may surround the fusion fuel with beryllium (or another neutron reflecting material) instead of depleted uranium to prevent further fission from occurring. [..]
Fusion, unlike fission, is relatively “clean”—it releases energy but no harmful radioactive products or large amounts of nuclear fallout. The fission reactions though, especially the last fission reaction, release a tremendous amount of fission products and fallout. If the last fission stage is omitted, by replacing the uranium tamper with one made of lead, for example, the overall explosive force is reduced by approximately half but the amount of fallout is relatively low. [..]
The tamper-pusher ablation proposed mechanism is that the primary compression mechanism for the thermonuclear secondary is that the outer layers of the tamper-pusher, or heavy metal casing around the thermonuclear fuel, are heated so much by the X-ray flux from the primary that they ablate away, exploding outwards at such high speed that the rest of the tamper recoils inwards at a tremendous velocity, crushing the fusion fuel and the spark plug.
Nuclear fission splits heavier atoms to form lighter atoms. Nuclear fusion bonds together lighter atoms to form heavier atoms. Both reactions generate roughly a million times more energy than comparable chemical reactions, making nuclear bombs a million times more powerful than non-nuclear bombs. [..]
When a free neutron hits the nucleus of a fissionable atom like uranium-235 ( 235U), the uranium splits into two smaller atoms called fission fragments, plus more neutrons. Fission can be self-sustaining because it produces more neutrons of the speed required to cause new fissions.
The uranium atom can split any one of dozens of different ways, as long as the atomic weights add up to 236 (uranium plus the extra neutron). The following equation shows one possible split, namely into strontium-95 ( 95Sr), xenon-139 (139Xe), and two neutrons (n), plus energy:
235U + n = 95Sr + 139Xe + 2n + 180MeV
The immediate energy release per atom is 180 million electron volts (MeV), i.e. 74 TJ/kg, of which 90% is kinetic energy (or motion) of the fission fragments, flying away from each other mutually repelled by the positive charge of their protons (38 for strontium, 54 for xenon). Thus their initial kinetic energy is 67 TJ/kg, hence their initial speed is 12,000 kilometers per second, but their high electric charge causes many inelastic collisions with nearby nuclei. The fragments remain trapped inside the bomb’s uranium pit until their motion is converted into x-ray heat, a process which takes about a millionth of a second (a microsecond).
This x-ray energy produces the blast and fire which are normally the purpose of a nuclear explosion.
After the fission products slow down, they remain radioactive. Being new elements with too many neutrons, they eventually become stable by means of beta decay, converting neutrons into protons by throwing off electrons and gamma rays. Each fission product nucleus decays between one and six times, average three times, producing a variety of isotopes of different elements, some stable, some highly radioactive, and others radioactive with half-lives up to 200,000 years. In reactors, the radioactive products are the nuclear waste in spent fuel. In bombs, they become radioactive fallout, both local and global.
Meanwhile, inside the exploding bomb, the free neutrons released by fission strike nearby U-235 nuclei causing them to fission in an exponentially growing chain reaction (1, 2, 4, 8, 16, etc.). Starting from one, the number of fissions can theoretically double a hundred times in a microsecond, which could consume all uranium up to hundreds of tons by the hundredth link in the chain. In practice, bombs do not contain that much uranium, and, anyway, just a few kilograms undergo fission before the uranium blows itself apart. [..]
- Materials which can sustain a chain reaction are called fissile. The two fissile materials used in nuclear weapons are: U-235, also known as highly enriched uranium (HEU), oralloy (Oy) meaning Oak Ridge Alloy, or 25 (the last digits of the atomic number, which is 92 for uranium, and the atomic weight, here 235, respectively); and Pu-239, also known as plutonium, or 49 (from 94 and 239). [..]
- Fusion is unlikely to be self-sustaining because it does not produce the heat and pressure necessary for more fusion. It produces neutrons which run away with the energy. In weapons, the most important fusion reaction is called the D-T reaction. Using the heat and pressure of fission, hydrogen-2, or deuterium (
- D), fuses with hydrogen-3, or tritium (3T), to form helium-4 (4He) plus one neutron (n) and energy:
2D + 3T = 4He + n + 17.6 MeV
Notice that the total energy output, 17.6 MeV, is one tenth of that with fission, but the ingredients are only one-fiftieth as massive, so the energy output per unit mass is greater. However, in this fusion reaction 80% of the energy, or 14 MeV, is in the motion of the neutron which, having no electric charge and being almost as massive as the hydrogen nuclei that created it, can escape the scene without leaving its energy behind to help sustain the reaction – or to generate x-rays for blast and fire.
The only practical way to capture most of the fusion energy is to trap the neutrons inside a massive bottle of heavy material such as lead, uranium, or plutonium. If the 14 MeV neutron is captured by uranium (either type: 235 or 238) or plutonium, the result is fission and the release of 180 MeV of fission energy, multiplying the energy output tenfold.
Fission is thus necessary to start fusion, helps to sustain fusion, and captures and multiplies the energy released in fusion neutrons. [..]
A third important nuclear reaction is the one that creates tritium, essential to the type of fusion used in weapons and, incidentally, the most expensive ingredient in any nuclear weapon. Tritium, or hydrogen-3, is made by bombarding lithium-6 ( 6Li) with a neutron (n) to produce helium-4 ( 4He) plus tritium ( 3T) and energy:
6Li + n = 4He + 3T + 5 MeV
A nuclear reactor is necessary to provide the neutrons. The industrial-scale conversion of lithium-6 to tritium is very similar to the conversion of uranium-238 into plutonium-239. [..]
However, an exploding nuclear bomb is a nuclear reactor. The above reaction can take place simultaneously throughout the secondary of a two-stage thermonuclear weapon, producing tritium in place as the device explodes.
Of the three basic types of nuclear weapon, the first, pure fission, uses the first of the three nuclear reactions above. The second, fusion-boosted fission, uses the first two. The third, two-stage thermonuclear, uses all three.
http://static.howstuffworks.com/gif/bunker-buster-intro.jpg URL: http://science.howstuffworks.com/bunker-buster.htm/printable Caption: Photo courtesy Air Force GBU-28 Bunker Buster
Description: http://static.howstuffworks.com/gif/bunker-buster1.jpg URL: http://science.howstuffworks.com/bunker-buster.htm/printable Caption: Photo courtesy Air Force F-111 & GBU-28 “Bunker Buster”
Description: http://static.howstuffworks.com/gif/bunker-buster-diagram.gif URL: http://science.howstuffworks.com/bunker-buster.htm/printable Caption: The finished bomb, known as the GBU-28 or the BLU-113, is 19 feet (5.8 meters) long, 14.5 inches (36.8 cm) in diameter and weighs 4,400 pounds (1,996 kg).
- Img: http://static.howstuffworks.com/gif/bunker-buster3.jpg URL: http://science.howstuffworks.com/bunker-buster.htm/printable Caption:
- Photos courtesy U.S. Department of Defense
- An F-117 Nighthawk engages its target and drops a bunker buster during a testing mission at Hill Air Force Base, Utah.
http://static.howstuffworks.com/gif/bunker-buster6.jpg URL: http://science.howstuffworks.com/bunker-buster.htm/printable Caption:
Photos courtesy U.S. Department of Defense
An F-117 Nighthawk engages its target and drops a bunker buster during a testing mission at Hill Air Force Base, Utah.
http://static.howstuffworks.com/gif/bunker-buster7.jpg URL: http://science.howstuffworks.com/bunker-buster.htm/printable Caption: Photo courtesy U.S. Department of Defense
An F-15E Strike Eagle pilot and a weapons system officer inspect a GBU-28 laser-guided bomb.
http://static.howstuffworks.com/gif/bunker-buster8.jpg URL: http://science.howstuffworks.com/bunker-buster.htm/printable Caption: Photo courtesy U.S. Department of Defense
Air-to-air view of GBU-28 hard target bomb on an F-15E Eagle
IMG: http://www.mindfully.org/Nucs/2004/Bunker-Buster-Phelan1dec04a.jpg URL: http://www.mindfully.org/Nucs/2004/Bunker-Buster-Phelan1dec04.htm Caption: graphic source: http://www.usatoday.com/graphics/news/gra/gbuster/frame.htm 28nov04
MY COMMENT: These bombs were used to penetrate the World Trade Centers. They created the necessary entry holes for the planes. The bombs were attached to the underbelly of the planes and were fired just before the planes hit the towers. There were smart fuses to time their firing for exactly the right moment so that it would look like the planes crashed into the towers and made the entry holes. These bunker buster bombs were necessary because without them, it is highly likely that the planes would have either bounced off the perimeter walls of the towers or would have only partially penetrated the towers. Likewise, the Pentagon plane also carried this bunker buster bomb. This accounts for its very neat entry into the Pentagon.
The bunker buster bombs probably contained depleted uranium. This accounts for the white flash that came from the flames and sparks of melting metal seen in pictures. This is incorrectly attributed to thermite. Depleted uranium burns in a similar way to magnesium giving off an intense white flash.
In pictures taken of the World Trade Center planes, there is a bulging in the underbelly that looks like the outline of a missile.
Just before one of the planes hits the tower, there is a bright orange fireball at its nose-end just as it is about to make contact with the tower. This is the fireball of the bunker buster exploding as it hits the perimeter wall of the tower. The missile could be fired in a very precise manner because it was equipped with a smart fuse.
Hard Target Smart Fuse (HTSF)
The Hard Target Smart Fuze enables precision bombs with penetrating warheads to detonate at a desired point inside buried or reinforced concrete targets such as underground bunkers and command centers. Detonation occurs after a sensor tells the fuse that the weapon has passed through a pre-programmed number of hard layers or voids in the target.
One of the newest weapons in the Air Force’s arsenal of hard target penetrating bombs is the AFRL Munitions Directorate-developed Advanced Unitary Penetrator (AUP), equipped with the Hard Target Smart Fuze. [..] The HTSF, designated the FMU-157/B, is an active decision-making accelerometer-based fuzing system capable of counting layers and voids (floors), as well as calculating distance traveled. When the weapon reaches the pre-determined floor it tells the bomb to explode. The HTSF is compatible with a variety of penetrating warheads.
The Hard-Target Smart Fuze [HTSF], developed at the Wright lab, is a microcontroller-based, in line fuze designed to be physically and electrically compatible with GBU-10, GBU-15, GBU-24, GBU-27, GBU-28, AGM-130, and general purpose MK-80 series weapons. The HTSF was designed for current and future penetrator weapons to define the fuze function point as either a desired distance within a desired void or a depth of burial beneath a hard layer. It operates in one of three modes: hard-layer detection, void detection, and path-length integration. It also has an adjustable backup time delay that is set in 1-msec increments with a maximum delay of 250 msec. The HTSF uses a void sensing technique to count layers within a structure to initiate fuze function, a depth of burial mode that causes the fuze to function a preset distance after it senses a hard layer, and an integral time delay backup.
Mark 83 – strategic nuclear bomb designed to be carried by aircraft
- Yield: Low Kt to 1.2 Kt
- Fusing: Retarded Airburst, and Contact Laydown.
- Number Produced: 650
- Weight: 2,400 lbs.
- Dimensions: 18″ x 145″
The Mark 83 is the current high-yield strategic TN bomb. 650 were produced between June, 1983 and 1991. In 1997, all were in service.
The B61 (Mark-61) bomb
http://upload.wikimedia.org/wikipedia/commons/thumb/6/6e/B-61_bomb.jpg/300px-B-61_bomb.jpg URL: http://en.wikipedia.org/wiki/B61_nuclear_bomb Caption: B61 about to be loaded
The B61, which exists in several mods, is actually a family of weapons based on a single basic weapon and physics package design. The physics package of the B61 has been adapted to yield several other warheads – the W-80, W-81 (now retired and dismantled), W-84 (now retired and in the inactive stockpile), and the W-85 (which was retired, and then readapted to yield another B61 variant). See W-80 page for pictures of the actual warhead.
Two stage radiation implosion weapon.
Light weight, intermediate yield bomb with variable yield options (“dial-a-yield” or DAY), and flexible fuzing and delivery options. Designed for high-speed external carriage and low altitude delivery. Modular weapon system design.
Contains two neutron generators (supplied by General Electric).
Spin stabilized by rocket. 24 ft. Nylon/Kevlar-29 ribbon parachute ejected by gas generator. Allows rapid deceleration from supersonic velocity (only 2 seconds required to decelerate to 35 mph). Tested at up to Mach 1.2.
The lowest yield option for the B61 (the same for all tactical mods) is 300 tons which probably represents the basic unboosted yield of the fission primary.
The B61 has four major sections:
- Nose Subassembly: contains a dual-channel radar airburst fuze and two piezoelectric crystal impact fuzes, and shock mitigating material for laydown delivery.
- Center Warhead Subassembly: “hard case” containing the actual thermonuclear warhead, sealed and desiccated with polyurethane spacers to support warhead and provide shock isolation. Also contains thermal batteries, safeties, and firing circuits.
- Rear Subassembly: Preflight arming controls, fuzing option switches, safe separation setting dials, and spin rockets for free fall weapon stabilization.
- Tail Subassembly: consists of bomb fins, afterbody structure, parachute with associated deployment and release mechanisms. Complete parachute assembly weighs 115 lb.
http://upload.wikimedia.org/wikipedia/commons/thumb/a/ae/B-61_bomb_%28DOE%29.jpg/220px-B-61_bomb_%28DOE%29.jpg URL: http://en.wikipedia.org/wiki/B61_nuclear_bomb Caption: B61 bomb in various stages of assembly. The nuclear component is the smaller silver cylinder behind the nose cone.
Primary consists of beryllium reflected plutonium (the derivative W80-0 contains supergrade plutonium)
- Deuterium-tritium boosted
- Primary also contains aluminum and uranium
- Contains oralloy (highly enriched uranium), either in primary or as secondary tampe
- Lithium-6 (95% enrichment) deuteride fusion fuel
http://upload.wikimedia.org/wikipedia/commons/thumb/7/7a/B61internals.png/220px-B61internals.png URL: http://en.wikipedia.org/wiki/B61_nuclear_bomb Caption: Internal nuclear components of the B61 bomb.
The B61 (Mk-61) Bomb
|Length (body)||10 ft 10.75 in (130.75 in)|
|Length (incl. fins)||11 ft 9.5 in (141.5 in)|
|Body Diameter||13.4 in|
|Tail Fin Span||22.5 in|
|Number In Service||600 (tactical), 750 (strategic)|
|Available Yields (Kt)||0.3 / 1.5 / 60 / 170|
|Available Yields (Kt)||0.3 / 1.5 / 10 / 45|
|Available Yields (Kt)||10 / ? / 340|
|Available Yields (Kt)||0.3 / 5 / 10 / 80|
|Available Yields (Kt)||0.3? / ? / 340|
Flash of ordnance
IMG1: http://img102.imageshack.us/img102/7686/050929f0000r001ii5.jpg IMG2: http://img102.imageshack.us/img102/2231/050929f0000r002ua1.jpg URL: http://www.abovetopsecret.com/forum/thread256010/pg1 Caption: The small-diameter bomb is a 250-pound class munition, providing the warfighter with a four-fold increase in weapons per aircraft station. It can penetrate more than 13 feet into a target and can be accurate from up to 70 miles away.
My comment: Look at the ordnance flash. Colors seen in this flash are white, yellow and orange. These colors reflect the high temperatures of the fireballs. The materials that burn in an explosion have high temperatures at which they vaporize. The white color is the highest temperature, next yellow, then orange and lastly red. [Include temperature chart of burning materials or steel] This flash looks like the one seen when the planes crashed into the Twin Towers and the Pentagon. On these occasions, the flashes were seen just as the planes hit or were about to hit the buildings.
Fission Weapons – from Federation of American Scientists
An ordinary “atomic” bomb of the kinds used in World War II uses the process of nuclear fission to release the binding energy in certain nuclei. The energy release is rapid and, because of the large amounts of energy locked in nuclei, violent. The principal materials used for fission weapons are U-235 and Pu-239, which are termed fissile because they can be split into two roughly equal-mass fragments when struck by a neutron of even low energies. When a large enough mass of either material is assembled, a self-sustaining chain reaction results after the first fission is produced.
The minimum mass of fissile material that can sustain a nuclear chain reaction is called a critical mass and depends on the density, shape, and type of fissile material, as well as the effectiveness of any surrounding material (called a reflector or tamper) at reflecting neutrons back into the fissioning mass. Critical masses in spherical geometry for weapon-grade materials are as follows:
|Bare sphere:||56 kg||11 kg|
|Thick Tamper:||15 kg||5 kg|
The critical mass of compressed fissile material decreases as the inverse square of the density achieved. Since critical mass decreases rapidly as density increases, the implosion technique can make do with substantially less nuclear material than the gun-assembly method. The “Fat Man” atomic bomb that destroyed Nagasaki in 1945 used 6.2 kilograms of plutonium and produced an explosive yield of 21-23 kilotons [a 1987 reassessment of the Japanese bombings placed the yield at 21 Kt]. Until January 1994, the Department of Energy (DOE) estimated that 8 kilograms would typically be needed to make a small nuclear weapon. Subsequently, however, DOE reduced the estimate of the amount of plutonium needed to 4 kilograms. Some US scientists believe that 1 kilogram of plutonium will suffice.
If any more material is added to a critical mass a condition of supercriticality results. The chain reaction in a supercritical mass increases rapidly in intensity until the heat generated by the nuclear reactions causes the mass to expand so greatly that the assembly is no longer critical.
Fission weapons require a system to assemble a supercritical mass from a sub-critical mass in a very short time. Two classic assembly systems have been used, gun and implosion. In the simpler gun-type device, two subcritical masses are brought together by using a mechanism similar to an artillery gun to shoot one mass (the projectile) at the other mass (the target). The Hiroshima weapon was gun-assembled and used 235 U as a fuel. Gun-assembled weapons using highly enriched uranium are considered the easiest of all nuclear devices to construct and the most foolproof.
Implosion-Device – from Federation of American Scientists
Because of the short time interval between spontaneous neutron emissions (and, therefore, the large number of background neutrons) found in plutonium because of the decay by spontaneous fission of the isotope Pu-240, Manhattan Project scientists devised the implosion method of assembly in which high explosives are arranged to form an imploding shock wave which compresses the fissile material to supercriticality.
The core of fissile material that is formed into a super-critical mass by chemical high explosives (HE) or propellants. When the high explosive is detonated, an inwardly directed implosion wave is produced. This wave compresses the sphere of fissionable material. The decrease in surface to volume ratio of this compressed mass plus its increased density is then such as to make the mass supercritical. The HE is exploded by detonators timed electronically by a fuzing system, which may use altitude sensors or other means of control.
The nuclear chain-reaction is normally started by an initiator that injects a burst of neutrons into the fissile core at an appropriate moment. The timing of the initiation of the chain reaction is important and must be carefully designed for the weapon to have a predictable yield. A neutron generator emits a burst of neutrons to initiate the chain reaction at the proper moment —- near the point of maximum compression in an implosion design or of full assembly in the gun-barrel design.
A surrounding tamper may help keep the nuclear material assembled for a longer time before it blows itself apart, thus increasing the yield. The tamper often doubles as a neutron reflector.
Implosion systems can be built using either Pu-239 or U-235 but the gun assembly only works for uranium. Implosion weapons are more difficult to build than gun weapons, but they are also more efficient, requiring less SNM and producing larger yields. Iraq attempted to build an implosion bomb using U-235. In contrast, North Korea chose to use 239 Pu produced in a nuclear reactor.
other mass (the target). The Hiroshima weapon was gun-assembled and used 235 U as a fuel. Gun-assembled weapons using highly enriched uranium are considered the easiest of all nuclear devices to construct and the most foolproof.
Fusion Weapons – From Federation of American Scientists
A more powerful but more complex weapon uses the fusion of heavy isotopes of hydrogen, deuterium, and tritium to release large numbers of neutrons when the fusile (sometimes termed “fusionable”) material is compressed by the energy released by a fission device called a primary. Fusion (or ‘‘thermonuclear’ weapons derive a significant amount of their total energy from fusion reactions. The intense temperatures and pressures generated by a fission explosion overcome the strong electrical repulsion that would otherwise keep the positively charged nuclei of the fusion fuel from reacting. The fusion part of the weapon is called a secondary.In general, the x-rays from a fission primary heat and compress material surrounding a secondary fusion stage.
It is inconvenient to carry deuterium and tritium as gases in a thermonuclear weapon, and certainly impractical to carry them as liquefied gases, which requires high pressures and cryogenic temperatures. Instead, one can make a “dry” device in which 6Li is combined with deuterium to form the compound 6Li D (lithium-6 deuteride). Neutrons from a fission “primary” device bombard the 6 Li in the compound, liberating tritium, which quickly fuses with the nearby deuterium. The a particles, being electrically charged and at high temperatures, contribute directly to forming the nuclear fireball. The neutrons can bombard additional 6Li nuclei or cause the remaining uranium and plutonium in the weapon to undergo fission. This two-stage thermonuclear weapon has explosive yields far greater than can be achieved with one point safe designs of pure fission weapons, and thermonuclear fusion stages can be ignited in sequence to deliver any desired yield. Such bombs, in theory, can be designed with arbitrarily large yields: the Soviet Union once tested a device with a yield of about 59 megatons.
In a relatively crude sense, 6 Li can be thought of as consisting of an alpha particle ( 4He) and a deuteron ( 2H) bound together. When bombarded by neutrons, 6 Li disintegrates into a triton ( 3 H) and an alpha:
6 Li + Neutron = 3 H + 3 He + Energy.
This is the key to its importance in nuclear weapons physics. The nuclear fusion reaction which ignites most readily is
2 H + 3 H = 4 He + n + 17.6 MeV,
or, phrased in other terms, deuterium plus tritium produces 4He plus a neutron plus 17.6 MeV of free energy:
D + T = 4 He + n + 17.6 MeV.
Lithium-7 also contributes to the production of tritium in a thermonuclear secondary, albeit at a lower rate than 6Li. The fusion reactions derived from tritium produced from 7 Li contributed many unexpected neutrons (and hence far more energy release than planned) to the final stage of the infamous 1953 Castle/BRAVO atmospheric test, nearly doubling its expected yield.
Underground Nuclear Weapons Testing – From FAS (illustrate with your own diagrams of WTC) – THESE ARE THE STEPS THE PERPS TOOK TO DEMOLISH THE WTC TWIN TOWERS)
The following description of a vertical drill-hole test breaks down the operation into seven individual steps:
Step1. Site Selection and Drilling.
There are two subsets of site selection as it applies to nuclear tests, namely: selection of an existing drill hole for a specific event, and selection of a new drill site from the Nuclear Test Zone for a specific event because the stockpile does not contain a suitable site. The goal of siting is to optimize the various parameters so that operational feasibility and successful containment of yields of interest to device designers can be attained at a suitably low cost.
Many factors are considered. Some of these are: (1) scheduling of field resources; (2) event schedules; (3) shock sensitivity of a given experiment and possible interactions with other experiments; (4) depth range required for a suitable device emplacement; (5) geologic structure; (6) geologic material properties; (7) depth of standing water; (8) potential drilling problems; (9) adjacent expended sites, craters, chimneys, subsurface collapses; (10) adjacent open emplacement holes or unplugged post-shot or exploratory holes; and (11) non-test program constraints such as groundwater concerns, roads, and power lines (Olsen, 1993).
When drilling is required after a test location is chosen by the sponsoring national laboratory, a drilling program outlining the requirements of the specific hole is completed. The event site is surveyed, staked, and checked for cultural and biological resources. When all environmental clearances are completed, the site is graded and leveled, and a drilling-fluid sump is constructed to contain drilling fluid and cuttings. A drill rig, usually with its own power and utilities, is moved onto the site. Water is brought in by truck, or piped in, and mixed with drilling compounds to fill the sump. The hole is then drilled using standard NTS big-hole drilling techniques. A normal hole is from 1 to 3 meters (m) (48 to 120 inches [in.]) diameter and from 213 to 762 meters (m) (600 to 2,500 feet [ft]) deep. During drilling, samples of drill cuttings are collected at 3-m (10-ft) intervals, and rock cores are taken as required. After drilling is complete,geophysical logs are run into the hole to evaluate the condition of the hole and gain a more thorough understanding of the geology. The drill site is then secured by filling the sump and installing specially designed covers over the hole.
Step 2. Event-Site Engineering and Construction.
When a hole is selected as a location for a nuclear test, the area around the hole is surveyed and staked according to the criteria set forth by the sponsoring national laboratory. The cultural and biological surveys are then rerun to determine if the status of the area has changed. The hole is also uncovered, and selected geophysical logs are refed in the hole to reconfirm its condition.
Once it is assured that the environmental clearances are complete, an area is cleared and leveled for the surface ground-zero equipment; another area close by the selected site is cleared and leveled for the recording trailer park. This is a typical earthmoving operation; native materials are used to top the pads or, if active material is unstable, decomposed granite fill is used. The on-site construction is temporary and is abandoned after the event is complete. Concrete pads are poured around the surface ground-zero to provide a stable platform for downhole operations and to provide a base for the assembly towers. Equipment is moved in to emplace the nuclear device in the hole, record the data produced, and provide radiological and seismic monitoring of the site. An extensive grounding system is used to establish baseline instrumentation grounds, which might include a pit containing salt water. The equipment to be left in position during the explosion is protected with an aluminum-foil hexcell-shaped shock-mounting material or dense foam. A circle of radiation detectors is placed back from the surface ground-zero to detect and assess any releases from the experiment. Finally, a perimeter fence is erected, and access is controlled both into and out of the event site.
Step 3. Device Delivery and Assembly.
For safety reasons, the nuclear device is delivered to the NTS unassembled. The device is assembled and inserted into a container at the Device Assembly Facility in Area 6 or in the Area 27 Assembly/Staging Facilities. The Device Assembly Facility is discussed at the end of this section. The device, now encased in the container, is delivered to the event site accompanied by armored convoy. It is then attached to the diagnostics canister in preparation for emplacement into the hole. Checks are run, and alignment is assured. Heavy security is maintained during all operations that involve the nuclear device.
Step 4. Diagnostic Assembly.
A diagnostic canister is assembled off site and transported to the test site. A typical diagnostic canister might be 2 m (8 ft) in diameter and 30 m (120 ft) long and contain all the instrumentation required to receive data at the time of the explosion (real time). The diagnostic canister might contain lead and other materials as shielding for the detectors. Upon arrival at the event site, the diagnostic canister is installed in the assembly tower to be mated with the device on site. Instrumentation cables are connected to the experiments and the recording trailer park. Slack in the cables allows the diagnostic canister to be lowered into the hole.
Step 5. Emplacement of the Experiment.
The nuclear explosive and special measurement devices are moved to the hole and lowered to the detonation position; all required diagnostic materials and instrumentation cables are also lowered into the hole at this time. Downhole operations are conducted according to a defined checklist and are monitored by independent inspectors. The whole assembly is placed on a set of fracture-safe beams that span the opening. Any auxiliary equipment is then lowered into the hole, and the area is secured. Emplacement equipment is removed from the area, and test runs are conducted on the downhole experiment.
The hole is stemmed to prevent radioactive materials from escaping during or after the experiment. Stemming materials used to backfill the hole are generally placed in alternating layers, according to the containment specification. Alternate layers of 1-centimeter (cm) (3/8–in.) pea gravel are combined with fine material to provide a barrier equal to or better than the undisturbed material. Sand, gypsum, grout, cold tar, or epoxy plugs are also placed in the hole to provide impenetrable zones. In these zones, the instrument cables are sealed to prevent a radioactive gas path to the surface. Once completed, the area is cleared of unnecessary equipment. A report is compiled for the Containment Evaluation Panel to show that the as-built condition reflects the containment design plan.
Step 6. Test Execution.
After the Containment Evaluation Panel accepts the as-built design of containment and all preliminary tests are successful, the nuclear device is ready for detonation. Security operations begin two days before the test to assure that all nonevent-related personnel are evacuated prior to the test for security and personal safety. The explosive is armed. Radiation monitors are activated, and aircraft with tracking capability circle the site in case gas and debris unexpectedly vent to the surface. Weather forecasts and fallout pattern predictions are reviewed. Then, detonation occurs.
When an underground nuclear device is detonated, the energy release almost instantaneously produces extremely high temperatures and pressure that vaporizes the nuclear device and the surrounding rock. Within a fraction of a second after detonation, a generally spherical cavity is formed at the emplacement position. As the hot gases cool, a lining of molten rock puddles at the cavity bottom.
After a period of minutes to hours, as the gases in the cavity cool, the pressure subsides and the weight of the overburden causes the cavity roof to collapse, producing a vertical, rubble-filled column known as a rubble chimney.
The rubble chimney commonly extends to the ground surface, forming a subsidence crater. Numerous subsidence craters are present at the test site. Subsidence craters generally are bowl-shaped depressions with a diameter ranging from about 60 to 600 m (200 to 2,000 ft) and a depth ranging from a few meters up to 60 m (200 ft), depending on the depth of burial and the explosive energy yield. Some deeply buried explosions of low yield form cavities that do not collapse to the surface and, consequently, do not create subsidence craters. Past underground nuclear tests in Yucca Flat and on Pahute Mesa have fractured the ground surface above the explosions, causing displacement of the surface along preexisting faults adjacent to explosion sites.
After the test is conducted, the event site remains secure until it can be assured that the event has been contained. After a suitable time, a reentry crew is dispatched to the site. Data are retrieved, and the condition of equipment is noted. After all is assured to be secure, normal NTS operations resume. The event site is roped off, outlining an exclusion zone where there is danger of potential cratering.
Step 7. Post-shot Operations.
After the temperature of the cavity has cooled, a post-shot hole is usually drilled into the point of the explosion in order to retrieve samples of the debris. These samples are highly radioactive, but provide important information on the test. The post-shot hole is as small in diameter as possible and is drilled at an angle to allow the drill rig to be positioned safely away from surface ground-zero. After drilling and sampling operations are complete, the drill rig and tools are decontaminated. Residual radiation is cleaned up at the site, and the hole is plugged back to the surface. This generally completes the event operation, and the site is turned back to the DOE.
Plutonium manufacture and Fabrication – from Nuclear Weapon Archive
All plutonium originates in nuclear reactors and is produced by the capture of extra neutrons by uranium-238 to form U-239, which then undergoes a series of decays to form Pu-239:
U-238 + n -> U-239 -> Np-239 -> Pu-239
Some of this plutonium gets consumed by fission before it is removed from the reactor, and some of it gets transmuted to heavier isotopes of plutonium by capturing more neutrons:
Pu-239 + n -> Pu-240
The isotopic composition of plutonium is affected by how long it stays in the reactor. Short exposures produce plutonium with very little Pu-240 and with very little plutonium being consumed by fission. Long exposures produce high Pu-240 concentrations, and a substantial portion of the plutonium produced is consumed by fission.
The isotopic composition matters with regard to manufacturing weapons for two reasons.
- First (and least important) is that Pu-240 is less fissile then Pu-239, so somewhat more plutonium is needed to make up the required amount for the weapon,
- Second (and more important) is that Pu-240 decays through spontaneous fission, producing a substantial flux of neutrons.
In the earliest years of weapon design the emission of neutrons was a problem in making a reliable efficient weapon because of the problem of predetonation. A high neutron flux makes it difficult or impossible to compress a bomb core containing several kilograms of plutonium to supercriticality before the bomb disassembled with a greatly reduced yield. The advent of composite cores containing highly enriched U-235 and plutonium (in the late 1940s) greatly reduced this difficulty though since the option of using a relatively small amount of plutonium in a mostly uranium core became available. The later development of fusion boosted weapons (in the mid 1950s) eliminated it entirely since the fusion boosting effect ensures efficient weapons, even with low initial fission yields.
Plutonium can be obtained from special purpose plutonium production reactors, or as a by-product of commercial power or research reactors. The plutonium produced by special purpose production reactors has a relatively low Pu-240 content (20% and is called “reactor grade”.
Essentially all of the plutonium currently in weapons throughout the world was produced in special purpose plutonium production reactors. Initially each of the five declared nuclear powers began producing plutonium for weapons on a large scale many years before they developed significant numbers of commercial power reactors. Special purpose reactors were required for weapons production because there was no other sources of plutonium available.
These special purpose reactors produce “weapon grade” plutonium, as opposed to grades with higher Pu-240 concentrations, for two reasons:
1. Economics: the only reason the reactor exists is to produce plutonium. Burning plutonium up in fission, or transmuting it to less fissile Pu-240 reduces output and increases cost (up to a point, this must be balanced against the cost of processing fuel with low plutonium concentrations).
2. Handling problems: although neutron emissions do not create serious problems in weapon design, it can produce problems with weapons manufacture and handling. Neutron emissions create occupational exposures to plutonium for those assembling weapons, or handling weapons already assembled. In fact weapons that are kept in close proximity to people (like the W80-0) may even require special “supergrade” low neutron emission plutonium for this reason.
http://gotexassoccer.com/elements/094Pu/Glovebx.jpg URL: http://gotexassoccer.com/elements/094Pu/Pu.htm Caption: Plutonium processing glove boxes.
The actual fabrication and processing of plutonium is done manually in glove boxes like these at Los Alamos, which means there is negligible shielding between the operator and the neutron-emitting plutonium.
The actual fabrication and processing of plutonium is done manually in glove boxes like these, which means there is negligible shielding between the operator and the neutron-emitting plutonium. If higher Pu-240 plutonium were used in weapons, then either remote control processing cells would have to be used, or the number of hours that each worker could spend at these tasks would have to be sharply reduced. Either of these would drive up the cost of weapon processing considerably. It is for this reason, as well as historical and policy reasons, that explain why reactor grade plutonium is not used in U.S. weapon. It is not due to any inherent inability to do so (contrary to some statements made by the nuclear power industry).
http://nuclearweaponarchive.org/Library/Plutonium/Brushpu.jpg URL: http://nuclearweaponarchive.org/Library/Plutonium/index.html Caption: Another example of a typical plutonium processing operation.
High-Purity Plutonium Ring
http://upload.wikimedia.org/wikipedia/commons/thumb/0/0f/Plutonium_ring.jpg/631px-Plutonium_ring.jpg URL: http://en.wikipedia.org/wiki/Plutonium Caption: A ring of weapons-grade 99.96% pure electrorefined plutonium, enough for one bomb core. The ring weighs 5.3 kg, is ca. 11 cm in diameter and its shape helps with criticality safety.
This ring of electrorefined plutonium metal has a purity of more than 99.96 per cent. It is typical of the rings that were prepared at Los Alamos and shipped to Rocky Flats for weapon fabrication before the latter facility was shut down, and U.S. weapon manufacture halted. The ring weighs 5.3 kilograms, enough for one bomb core, and is approximately 11 centimeters in diameter. The ring shape is important for criticality safety. There is enough plutonium in this ring to make a modern strategic nuclear weapon.
http://www.nuclearweaponarchive.org/Library/Plutonium/Puingot.jpg URL: http://nuclearweaponarchive.org/Library/Plutonium/ Caption:
Plutonium-gallium alloy ingot reclaimed from weapon pit (LLNL).
http://gotexassoccer.com/elements/094Pu/pu_data.jpg URL: http://gotexassoccer.com/elements/094Pu/Pu.htm Caption: Various images of plutonium metal.
http://gotexassoccer.com/elements/094Pu/pluton.jpg URL: http://gotexassoccer.com/elements/094Pu/Pu.htm Caption: Various images of plutonium metal.
http://gotexassoccer.com/elements/094Pu/Pu_LANL_b.jpg URL: http://gotexassoccer.com/elements/094Pu/Pu.htm Caption: A sample of 0.89 g of highly pure plutonium (99.99%). This sample, a standard for analysis, was
manufactured at Los Alamos, in a oxygen-free environment, and sealed under vacuum in a glass ampoule.
http://gotexassoccer.com/elements/094Pu/Pu_96B05592s.jpg URL: http://gotexassoccer.com/elements/094Pu/Pu.htm Caption:
Pu(IV) colors change with different ligands.
http://gotexassoccer.com/elements/094Pu/Pu_96B05591s.jpg URL:http://gotexassoccer.com/elements/094Pu/Pu.htm Caption: Colors of the different oxidation states of plutonium, in 1 M HClO4.
http://gotexassoccer.com/elements/094Pu/Pu_Abb1bs.jpg URL: http://gotexassoccer.com/elements/094Pu/Pu.htm Caption:
A hemisphere of purified, but gallium-stabilized, delta-phase plutonium metal.
http://gotexassoccer.com/elements/094Pu/Pubuttont.jpg URL: http://gotexassoccer.com/elements/094Pu/Pu.htm Caption:
Buttons of refined plutonium metal.
Gas centrifuge process
http://www.euronuclear.org/info/encyclopedia/images/gascentrifuge.jpg URL: http://www.euronuclear.org/info/encyclopedia/g/gascentrifuge.htm Caption:
Principle of a gas centrifuge process for uranium enrichment
Process to separate isotopes in which heavy atoms are split from the lighter atoms by centrifugal forces. The separation factor depends on the mass difference of the isotopes to be separated. The process is suitable for the separation of uranium isotopes, the achievable separation factor amounts to 1.25. Uranium enrichment plants applying this process are operated in Gronau/Wesphalia (Germany) and by URENCO at Capenhurst (UK).
What’s a uranium centrifuge?
By Marshall Brain
Uranium is an element that is similar to iron. Like iron, you dig uranium ore out of the ground and then process it to extract the pure uranium from the ore. When you finish processing uranium ore, what you have is uranium oxide. Uranium oxide contains two types (or isotopes) of uranium: U-235 and U-238. U-235 is what you need if you want to make a bomb or fuel a nuclear power plant. But the uranium oxide from the mine is about 99 percent U-238. So you need to somehow separate the U-235 from the U-238 and increase the amount of U-235. The process of concentrating the U-235 is called enrichment, and centrifuges are a central part of the process.
http://static.howstuffworks.com/gif/uranium-centrifuge-1.jpg URL: http://science.howstuffworks.com/uranium-centrifuge.htm Caption:
Photo courtesy Oak Ridge National Laboratory
Uranium centrifuge cascades
U-235 weighs slightly less than U-238. By exploiting this weight difference, you can separate the U-235 and the U-238. The first step is to react the uranium with hydrofluoric acid, an extremely powerful acid. After several steps, you create the gas uranium hexafluoride.
Now that the uranium is in a gaseous form, it is easier to work with. You can put the gas into a centrifuge and spin it up. The centrifuge creates a force thousands of times more powerful than the force of gravity. Because the U-238 atoms are slightly heavier than the U-235 atoms, they tend to move out toward the walls of the centrifuge. The U-235 atoms tend to stay more toward the center of the centrifuge.
Although it is only a slight difference in concentrations, when you extract the gas from the center of the centrifuge, it has slightly more U-235 than it did before. You place this slightly concentrated gas in another centrifuge and do the same thing. If you do this thousands of times, you can create a gas that is highly enriched in U-235. At a uranium enrichment plant, thousands of centrifuges are chained together in long cascades.
At the end of a long chain of centrifuges, you have uranium hexafluoride gas containing a high concentration of U-235 atoms.
The creation of the centrifuges is a huge technological challenge. The centrifuges must spin very quickly — in the range of 100,000 rpm. To spin this fast, the centrifuges must have:
- very light, yet strong, rotors
- well-balanced rotors
- high-speed bearings, usually magnetic to reduce friction
Meeting all three of these requirements has been out of reach for most countries. The recent development of inexpensive, high-precision computer-controlled machining equipment has made things somewhat easier. This is why more countries are learning to enrich uranium in recent years.
Now you need to turn the uranium hexafluoride gas back into uranium metal. You do this by adding calcium. The calcium reacts with the fluoride to create a salt, and the pure uranium metal is left behind. With this highly concentrated U-235 metal, you can either make a nuclear bomb or power a nuclear reactor.
http://upload.wikimedia.org/wikipedia/commons/d/d4/Yellowcake.jpg URL: http://en.wikipedia.org/wiki/Uranium Caption: Yellowcake is a concentrated mixture of uranium oxides that is further refined to extract pure uranium.
http://upload.wikimedia.org/wikipedia/commons/thumb/6/69/Gas_centrifuge_cascade.jpg/750px-Gas_centrifuge_cascade.jpg URL: http://en.wikipedia.org/wiki/Uranium Caption: Cascades of gas centrifuges are used to enrich uranium ore to concentrate its fissionable isotopes.
http://upload.wikimedia.org/wikipedia/commons/8/84/U_Oxstufen.jpg URL: http://en.wikipedia.org/wiki/Uranium Caption: Uranium in its oxidation states III, IV, V, VI
http://upload.wikimedia.org/wikipedia/commons/0/0b/Pichblende.jpg URL: http://en.wikipedia.org/wiki/Uranium Caption: Uraninite, also known as Pitchblende, is the most common ore mined to extract uranium.