What’s the lifespan of a nuke’s “pit” anyway?
- Experts are pleading with Congress to get a firm age limit on plutonium cores of U.S. nuclear weapons.
- A specific plutonium isotope powers nuclear weapons, but others power nuclear plants and space travel.
- The Trump administration wants to begin replacing cores, but a more scientific time frame could save a lot of “rush” money.
The U.S. has nearly 4,000 stockpiled nuclear weapons, and Scientific American wonders what will happen to all of their aging plutonium cores. Experts have said the plutonium will last at least 100 years, but it’s probably still smart to make backup plans—and the Trump administration is doing just that, with aims to replace all the cores by 2080.
Nuclear weapons with plutonium cores, mostly of the “implosion” type, replaced the original crude nuclear weapons beginning in 1945. These new weapons required plutonium as the fuel in their nuclear reactions, and plutonium is found in nature in only tiny amounts in very specific situations. To make enough to power thousands of weapons in the U.S. alone and thousands more around the world, a new plutonium production cottage industry sprang up.
Plutonium is part of the reactor makeup of many nuclear power plants, but reactor-grade plutonium and weapons-grade plutonium are different. The latter has always required dedicated production facilities, because plutonium that works in reactors is not right for weapons and can’t be substituted at any ratio. Weapons plutonium is made by subjecting nuclear materials to a short burn that produces plutonium-239, and the same materials left to “cook” for longer turn into plutonium-240.