Plutonium was named after the celestial body Pluto but was almost called "Extremium" or "Ultimum" because it was thought to be the last possible element on the periodic table.  Plutonium has at least 15 different isotopes, all of which are radioactive.

The majority of plutonium was produced for nuclear weapons in several government reactors designed to maximize the production of plutonium. Between 1944 and 1988, the U.S. built and operated these "production reactors" at high-security government facilities, including Hanford. In all, the US produced about 100 metric tons of plutonium.  Hanford produced approximately two-thirds of the plutonium used in the U.S. nuclear arsenal.

The reactors made plutonium by bombarding special fuel rods containing uranium with neutrons. Once the maximum amount of plutonium was produced, workers removed the fuel rods from the reactor. The spent fuel rods were extremely radioactive, and the process for recovering the plutonium used only remote-controlled equipment. This processing left behind over 100 million gallons of exceedingly hazardous mixed wastes of acids and radioactive fission products.

Internal exposure to plutonium is an extremely serious health hazard. It generally stays in the body for decades, exposing organs and tissues to radiation, and increasing the risk of cancer. Plutonium is also a toxic metal, and may cause damage to the kidneys.

Plutonium was first manufactured in 1940 at the University of California at Berkeley and was used soon after for Manhattan Project efforts. In 2004 a glass bottle holding the oldest specimen of wartime plutonium safe was excavated from a burial trench at the Hanford site. The bottle, manufactured in 1944, came from the X-10 Reactor at Oak Ridge, Tennessee.

Going Deeper

Richland Dock, 1956

Plutonium 239 (Lunch with a Rat)