Part 1 of 2 Parts
There is a glut of plutonium in the U.S. and Russia as a result of excessive warhead production during the Cold War. The U.S. peaked at thirty-seven thousand warheads in 1967. The Soviet Union peaked at forty-five thousand warheads in the 1970s. These arsenals could have destroyed human civilization many times over.
One big concern about all the excess plutonium at sites around the U.S. is that such weapons grade radioactive material is an attractive target for terrorists. A nuclear bomb can be made from about twenty-four pounds of plutonium. Plutonium emits alpha particles which can be stopped by a thin layer of glass or leather or even human skin. This makes plutonium an attractive material for terrorists because they can transport it without much danger of exposure to harmful levels of radioactivity. The main danger is that if particles of plutonium are inhaled, they can cause cancers.
During the Cold War, there was no discussion or thought given to methods for disposing of excess plutonium. It was only after the fall of the Soviet Union in 1991 that Russia and the U.S. began thinking about plutonium disposal. Currently, the U.S. has no long-term plan about what to do with its share of the plutonium which has a half-life of twenty-four thousand years.
At the U.S. Department of Energy Pantex facility near Amarillo, Texas, contract workers remove the plutonium cores from nuclear warheads that have been retired. This is a very dangerous job even with all the safety rules that are in place. The DoE has fifty-four metric tons of surplus plutonium at sites around the U.S. At the Pantex plant, there are many more than the twenty thousand cores maximum mandated by regulations and more are added every day.
Although the work at the Pantex plant gets little publicity, there is increasing pressure to dismantle nuclear warheads, so the U.S. will not exceed the 2010 Treaty limit of one thousand five hundred and fifty warheads. The U.S. wants to decommission and dismantle old nuclear warheads so they can replace them with newer and more deadly weapons. Russia is doing the same with their nuclear arsenal.
The U.S. has not begun work to get the additional space needed to bury the excess plutonium at least two thousand feet below the ground. This is considered a safe depth for the storage of plutonium. Currently, a great deal of the U.S.’s plutonium is stored in a building above ground at the DoE Savanna River Site in South Carolina. Local critics say that the building was never designed to store plutonium and that there is a significant risk of leakage of nuclear materials and/or serious nuclear accidents.
The DoE does have a small experimental nuclear weapons materials storage site in New Mexico. The DoE is having discussions with New Mexico officials to expand the site. Local environmental groups are very opposed to this idea.
Please read Part 2
Pantex plant in Texas:
Great progress has been made in nuclear disarmament since the height of the Cold War when both the U.S. and Russia had tens of thousands of nuclear warheads. Now they are down to about five thousand warheads each.
One of the big problems with nuclear disarmament is verification. The exact design of nuclear warheads is highly classified in all nations that possess them. How do you prove that a warhead has been destroyed without being able to examine the detail of its construction and the exact radioactive material that it contains? Up to this point, disarmament efforts have been focused on the elimination of delivery systems which are much easier to verify.
Scientists at MIT have published papers in Nature Communications and The Proceedings of the National Academy of Sciences that lay out their ideas for two different variations on a new verification system for nuclear warheads. Areg Danagoulian, the senior author of both papers, is a MIT assistant professor of nuclear science and engineering.
There are two essential elements in the construction of a nuclear warhead. The exact mixture of weapons grade radioactive materials and the dimensions of the core or “pit” that contains the radioactive materials. This is top secret military information.
Measuring the radiation given off by a supposed nuclear warhead is not enough to prove that it is really a nuclear warhead. It could a dummy warhead that contains non-weapons grade nuclear material that gives off the characteristic signature of a real warhead. There are isotope-sensitive resonant processes that can be used to analyze the exact isotope mixture and the shape and size of the pit but this would reveal the information that all nuclear armed nations want to keep secret. The MIT team came up with the idea of a physical “key” that would contain a sample of the isotopes that are in a real warhead. The group carrying out inspections of warheads would not know the exact mixture in the key.
One way to think about this system would be to substitute different colors for the different isotopes. The warhead would be visualized a combination of colors. A filter could be created that would combine the compliments of the colors representing the warhead. If the filter was laid over the sheet of colors representing the warhead, the result would be uniform black. If the warhead was a fake, then there would be visible colors when the filter was applied.
In the MIT system, the colors are replaced by isotopes. The country that produced a warhead would also produce the filter or key. The key would be a cryptographic reciprocal or a cryptographic foil. The warhead being inspected could be hidden inside a black box to prevent revealing its construction.
In one version of the MIT system, the warhead is lined up with the foil and a beam of neutrons applied. A detector then reveals the isotope-specific resonant signatures. The neutron scan is rendered as a visible image. If the image is blank, the warhead is real. If the warhead is not real, then the image shows details of its construction.
The alternative MIT system would use photons instead of neutrons to scan the foil and warhead. Instead of a visible image being generated, there would be a spectrogram. Both of these processes generate a Zero Knowledge Proof in which a nuclear armed nation can prove compliance without revealing any further information about the details of the construction of their warhead.
So far, the MIT team has only verified their design through sophisticated computer simulations. The next step is to test actual fissile materials at one of the U.S. national nuclear laboratories.