Plutonium-239 has a half-life of 25,000 years, meaning it takes that long to lose half of its radioactive potency. Uranium-235 has a half-life of 700 million years.

When plutonium-239 (which has a 24,000-year half-life) is mixed with 7.5 percent by weight of plutonium-238 (with an 87-year half-life), the alloy will accumulate radiation damage at a rate 16 ...

The half-life of plutonium-239 is 24,000 years, so if it escaped in smoke from a burning reactor and contaminated soil downwind, it would remain hazardous for tens of thousands of years.

It's also the second oldest known man-made plutonium 239, said Jon Schwantes, a PNNL senior research scientist who led the investigation. The oldest is held in the Smithsonian.

Plutonium is the 94th element in the periodic table and one of the most dangerous elements on Earth. ... When you hit a plutonium-239 atom with a neutron, more neutrons will spill out.

As it was said (and sang) in 1979, plutonium is forever…with thousands of years of radioactivity from nuclear fission (especially plutonium 239). Jeff Bezos—proving again that he is not ...

Scientists theorized plutonium-239 might offer a more efficient alternative to uranium-235 in a bomb. Compton and Nichols discussed the plutonium process in July 1942, and explored the process ...

The main fissile isotope of plutonium, 239 Pu, is made by bombarding 238 U with neutrons. Each atom of 238 U that absorbs a neutron becomes 239 U, a radioactive isotope with a half-life of only 23 ...

The X-10 Graphite Reactor Semiworks in Bethel Valley near Oak Ridge produced the first gram of man-made element Plutonium-239 before moving to the full-scale HEW site in Washington.