Plutonium (Pu) is a brittle, highly dense radioactive heavy metal with a silvery surface similar in appearance to nickel. Plutonium reacts chemically (oxidizes) when it is exposed to moist air. Finely divided plutonium metal dust ignites (catches fire) spontaneously in the presence of air; but this cannot happen with the larger shapes of plutonium found in weapons.

Plutonium's uses in the United States

Plutonium is used in the United States primarily in the manufacture of nuclear weapons. All the plutonium used in weapons production was man- made in reactors. There are 15 plutonium isotopes1; the principal plutonium isotope used in the manufacture of nuclear weapons is Pu-239. Other countries use plutonium as a fuel for commercial nuclear reactor power plants; however, the United States does not use plutonium for this purpose.

Due to proliferation and economic concerns associated with plutonium, some nations, including the United States, have decided to postpone or stop reprocessing commercial power reactor spent fuel for reuse in power reactors. In support of this stance, President Clinton announced on September 27, 1993, that "the United States does not encourage the civil use of plutonium and, accordingly, does not itself engage in plutonium reprocessing for either nuclear power or nuclear explosive purposes."

The health effects of plutonium?

Plutonium is a heavy metal and has toxicity's associated with this class of material. Plutonium also has a toxicity associated with its radioactivity. The radiation emitted during plutonium decay is primary alpha particles, although beta particles, neutrons, and gamma rays, which are all more penetrating than alpha particles, are also emitted. Outside the body, alpha particles are not very hazardous-you can stop an alpha particle with a sheet of paper.

The toxicity of plutonium depends on the route of exposure, particle size, chemical form, and isotope. Fine particles are more biologically hazardous than larger particles. Plutonium particles on a person's skin are not readily absorbed through the skin and can be washed off. Particles, however, are a potential hazard if they enter the body. The two primary routes through which plutonium particles can enter the body are ingestion or inhalation. Particles could also enter through open cuts or wounds. If plutonium oxide particles are ingested and enter the body's digestive system, very little of the plutonium is absorbed by the body, and most of the plutonium is naturally excreted within a few days.

Plutonium is not usually in a form which can be easily inhaled. The form of plutonium that might be inhaled in some cases is finely divided, dispersed plutonium oxide. Once inhaled, the plutonium could partially dissolve and be transported from the lungs to the liver, bone, and other organs. There, the radioactive toxicity could alter normal body cell functions and lead to cell death. Individual cell deaths are a normal occurrence, and most organs constantly regenerate. However, if cells are altered so that they reproduce irregularly, uncontrolled growth could lead to the development of cancer over time.

Plutonium and its Changes with Time

A typical plutonium sample is not pure plutonium-239, but consists of a mixture of isotopes. There are 15 isotopes of plutonium, with mass numbers ranging from 232 to 246. They are all radioactive, that is, their nuclei decay and in the process new elements are formed. All of the decay products of plutonium isotopes are also radioactive.

The isotopes commonly found in plutonium made in nuclear reactors range from plutonium-238 to plutonium-242. The amount of isotopes other than plutonium-239 produced in military or commercial reactors depends on the nature of the fuel used, the design of the reactor and to length of irradiation time.

The first is weapons grade plutonium (often abbreviated WPu), which contains 93 percent or more plutonium-239. The other is a typical composition of reactor-grade plutonium (often abbreviated RPu), as produced in nuclear power reactors of the light water design.

Plutonium produced in other reactors, such as graphite-moderated reactors (some of which are in operation in Britain, Russia, and elsewhere) or heavy water reactors used in Canada and elsewhere, has a composition in between that shown for weapons grade and reactor grade plutonium in the table.

The half-life refers to the amount of time it takes for one-half of the atoms in a given sample to disintegrate. The specific activity (which is inversely related to half-life), indicates the radioactivity of a certain weight of material. For example, if there was a pound of plutonium today, in 24 thousand years half a pound would have decayed into other elements, while the other half a pound would remain plutonium. It would take another 24 thousand years for half of the remaining half a pound of plutonium to decay into other elements, and so on.

CINCINNATI (AP) - Some former workers at a Department of Energy uranium-processing plant say inspectors commonly tasted radioactive salts to decide whether they would make good laboratory samples.
 Such practices are coming to light as scientists interview longtime employees in a medical-monitoring program that former workers at the Fernald site won in settling a lawsuit against the government.
 ``I don't know whether it was just stupidity or a lack of knowledge,'' Gene Branham, vice president of a coalition of 14 employee unions at the Fernald site, said Monday.
 During the 1950s, middle managers at the former Feed Materials Production Center at Fernald, 18 miles northwest of Cincinnati, would put a granular uranium hexafluoride substance called ``green salt'' on their tongues to check for the telltale metallic taste of a good sample.
 The managers apparently worried that if they sent samples of poor quality to a lab
for testing, their productivity records would suffer.   ``I'm sure they wouldn't have done it if they thought it was dangerous,'' said Susan Pinney, an associate professor of environmental health at the University of Cincinnati.  She is helping compile interviews with former Fernald workers to determine long-term health effects of continued exposure to radioactive materials.
 The Atomic Energy Commission, now part of the Energy Department, operated the Fernald site during its early years and failed to share with workers its information about the health hazards of radioactive materials, Branham said.  But state-of-the-art information in the 1950s wasn't what it is now, DOE spokesman Ken Morgan said.   ``I don't think it was ever anybody's policy that you should be sticking green salt in your mouth,'' Morgan said.  Branham, vice president of the Fernald Atomic Trades and Labor Council, has worked at the Fernald site since 1952, about a year after it started processing uranium for the government's production elsewhere of nuclear weapons. The so-called green salt was used in producing uranium ingots.  Production ended in 1989 but the cleanup of radioactive contamination at Fernald is expected to take until at least 2005.
 AP-NY-05-12-98 1229EDT
Copyright 1998 The Associated Press. The information contained in the AP news report may not be published, broadcast, rewritten or otherwise distributed without the prior written authority of The Associated Press.

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