Plutonium

Plutonium is a chemical element; it has symbol Pu and atomic number 94. It is a silvery-gray actinide metal that tarnishes when exposed to air, and forms a dull coating when oxidized. The element normally exhibits six allotropes and four oxidation states. It reacts with carbon, halogens, nitrogen, silicon and hydrogen. When exposed to moist air, it forms oxides and hydrides that can expand the sample up to 70% in volume, which in turn flake off as a powder that is pyrophoric. It is radioactive and can accumulate in bones, which makes the handling of plutonium dangerous.

historical subcritical mass of plutonium

1940s physicist who died of radiation poisoning (1921–1945)

thumb|upright=1.1|Reprocessing of spent nuclear fuel by the PUREX method, first developed in the 1940s to produce plutonium for nuclear weapons, was demonstrated commercially in Belgium to partially re-fuel a LWR in the 1960s. This aqueous chemical process continues to be used commercially to separate [[reactor grade plutonium (RGPu) for reuse as MOX fuel. It remains controversial, as plutonium can be used to make nuclear weapons.]]

nuclear thermal source whose heat is converted into electricity

core of an implosion weapon

criticality accident

The Multihundred-watt radioisotope thermoelectric generator (MHW RTG) is a type of US radioisotope thermoelectric generator (RTG) developed for the Voyager spacecraft, Voyager 1 and Voyager 2. The Voyager generators continue to function nearly 50 years into the mission.

plutonium extraction process

American historian, professor (University of Maryland, Baltimore County)

substance that is pure enough to be used to make a weapon

six or seven different forms that pure plutonium metal can take