HKNIC - More about Managing Spent Fuel

More about Managing Spent Fuel
Plutonium from a commercial reactor is not suitable for nuclear weapon

Plutonium 239 (Pu-239) is a material that can be used for nuclear weapons. It is produced in a nuclear reactor when neutrons are absorbed by uranium 238 to become Pu-239. However, the Pu-239 absorbs neutrons in the reactor and soon becomes Pu-240, reducing the purity of the Pu-239 in the nuclear fuel.

Since the nuclear fuel in a commercial reactor will typically stay in the reactor for several years, the Pu-239 produced will be contaminated with Pu-240, making it unsuitable as weapons grade material. Weapons grade plutonium generally needs over 90% pure Pu-239, since only this level of concentration will allow the weapon to use most of the nuclear material and so create an explosion. The material may simply produce heat without an explosion if there is too much impurity

While reprocessing extracts the plutonium from the spent fuel, it does not change the proportion of the Pu-240 in the plutonium, and so it remains unsuitable as material for a nuclear weapon.

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