plutonium 239

Thesaurus

Noun

1.

plutonium 239 - a highly fissionable isotope of plutonium that is used in atomic weapons and as a reactor fuel; produced by irradiating uranium 238 with slow electrons atomic number 94, plutonium, Pu - a solid silvery grey radioactive transuranic element whose atoms can be split when bombarded with neutrons; found in minute quantities in uranium ores but is usually synthesized in nuclear reactors; 13 isotopes are known with the most important being plutonium 239 weapon-grade plutonium, weapons plutonium - plutonium 239 that is recovered when nuclear weapons are disassembled; it is stored in plutonium pits