The half-life is the time it takes for half the atoms of an element to decay. For instance, plutonium has a half-life of 24, years while plutonium has a half-life of The various isotopes also have different principal decay modes. The isotopes present in commercial or military plutonium are plutonium, , and Table 2 shows a summary of the radiological properties of five plutonium isotopes. The isotopes of plutonium that are relevant to the nuclear and commercial industries decay by the emission of alpha particles, beta particles, or spontaneous fission.
Gamma radiation , which is penetrating electromagnetic radiation, is often associated with alpha and beta decays. Various sources give slightly different figures for half-lives and energies. Table 3 describes the chemical properties of plutonium in air. These properties are important because they affect the safety of storage and of operation during processing of plutonium.
The oxidation of plutonium represents a health hazard since the resulting stable compound, plutonium dioxide is in particulate form that can be easily inhaled.
It tends to stay in the lungs for long periods, and is also transported to other parts of the body. Ingestion of plutonium is considerably less dangerous since very little is absorbed while the rest passes through the digestive system. Plutonium combines with oxygen, carbon, and fluorine to form compounds which are used in the nuclear industry, either directly or as intermediates.
Table 4 shows some important plutonium compounds. Plutonium metal is insoluble in nitric acid and plutonium is slightly soluble in hot, concentrated nitric acid. However, when plutonium dioxide and uranium dioxide form a solid mixture, as in spent fuel from nuclear reactors, then the solubility of plutonium dioxide in nitric acid is enhanced due to the fact that uranium dioxide is soluble in nitric acid.
This property is used when reprocessing irradiated nuclear fuels. The subsequent absorption of a neutron by plutonium results in the formation of plutonium Absorption of another neutron by plutonium yields plutonium The higher isotopes are formed in the same way. Since plutonium is the first in a string of plutonium isotopes created from uranium in a reactor, the longer a sample of uranium is irradiated, the greater the percentage of heavier isotopes.
Plutonium must be chemically separated from the fission products and remaining uranium in the irradiated reactor fuel. This chemical separation is called reprocessing. It is important to remember that this classification of plutonium according to grades is somewhat arbitrary.
The ability of countries to build nuclear arsenals from reactor grade plutonium is not just a theoretical construct. It is a proven fact. All grades of plutonium can be used as weapons of radiological warfare which involve weapons that disperse radioactivity without a nuclear explosion.
Posted on July, Last modified April, Download this page as a PDF. Table 1. C Boiling point: deg. Table 2. Chemical properties and hazards of plutonium. Table 3. Humid, elevated temperatures PuO2 readily reacts to form plutonium dioxide Important Plutonium Compounds and their Uses Plutonium combines with oxygen, carbon, and fluorine to form compounds which are used in the nuclear industry, either directly or as intermediates.
Table 4. Formation and Grades of Plutonium Plutonium is formed in both civilian and military reactors from uranium Table 5. Remember that, through neutron capture, a reactor produces Pu Am is an alpha emitter and it decays to a lighter variety of neptunium Np which, when subjected to neutron irradiation, captures a neutron to become Np One final transformation — a last beta decay — is the last step to producing Pu This is the reason why Pu is so expensive — making it requires two bouts of irradiation the first long enough to produce the Pu , enough time for all of the radioactive decays to transform plutonium into americium and the americium into neptunium, and several steps of chemical processing to isolate the various elements of interest that are formed.
Although it sounds convoluted well, I guess it is convoluted , making Pu is fairly straight-forward. The science and engineering are both well-known and well-established, and its production certainly breaks no new scientific or technical ground. As I mentioned last week, the American Pu production line shut down over two decades ago. So this option is not going to work for much longer, regardless of the future of US-Russian international relations.
But if there is a Pu stockpile at LANL it would certainly be nice to tap it for space exploration — not to mention the savings in disposal costs. Yet another way to make Pu is in a liquid fluoride thorium reactor LFTR — a reactor that uses naturally occurring thorium Th to breed U, which fissions quite nicely. Additional neutron captures can turn U into Pu, which can be chemically separated from the fuel.
There may be scraps of the material — possibly even stockpiles — at various DOE facilities, but dismantling nuclear weapons is probably not going to do the job.
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