The longest-lived are plutonium-244, with a half-life of 80.8 million years, plutonium-242, with a half-life of 373,300 years, and plutonium-239, with a half-life of 24,110 years.
A confidential report from the department, made public on Thursday by the private Nuclear Control Institute, said the cost of the 22-year plutonium disposal program that resulted from the agreement with the Russians had now risen to $6.6 billion -- a 50percentt increase over a 1999 estimate.
Documents provided to Mr. Holmes said Dow and the Atomic Energy Commission were aware for years that plutonium was leaking onto the dry ground and that plutonium-contaminated dust was blowing toward downtown Denver, 16 miles away.
With solidification, the solid would have to last thousands of years because plutonium decays slowly.
Currently, its workers clean up radioactive and hazardous waste created during 40 years of plutonium production for nuclear weapons.
But cancer rates are telling the tale: they remain elevated in neighborhoods around Rocky Flats 30 years on (plutonium has a half-life of 24,000 years).
One problem identified in the latest audit is that over 40 years of plutonium production involving many different processes, little priority was given to keeping a detailed waste inventory.
The fear is that in a few hundred years, the plutonium could reach an underground area called the saturated zone, where water flows, and from there enter the Columbia River.
The transuranic elements in spent fuel are Neptunium-237 (half-life two million years) and Plutonium-239 (half-life 24,000 years).
The most troublesome transuranic elements in spent fuel are neptunium-237 (half-life two million years) and plutonium-239 (half-life 24,000 years).
