Power reactors have been responsible for the production of a vast quantity of weapons-useable plutonium. A typical power reactor (1000 MWe) produces about 300 kilograms of plutonium each year. Total global production of plutonium in power reactors is about 70 tonnes per year. As at the end of 2009, power reactors had produced an estimated 2000 tonnes of plutonium.
Using the above figures, and assuming that 10 kilograms of (‘reactor grade’) plutonium is required to produce a weapon with a destructive power comparable to that of the plutonium weapon dropped on Nagasaki in 1945:
- The plutonium produced in a single reactor each year is sufficient for 30 weapons.
- Total global plutonium production in power reactors each year is sufficient to produce 7,000 weapons.
- Total accumulated ‘civil’ plutonium is sufficient for 200,000 weapons.
The ‘reactor-grade’ plutonium routinely produced in nuclear power reactors can be used in nuclear weapons though there are ongoing debates concerning the implications for weapon reliability and yield. Moreover, using a power reactor to produce many hundreds of kilograms of weapon grade plutonium per year could hardly be simpler – all that needs to be done is to shorten the irradiation time, thereby maximising the production of plutonium-239 relative to other, unwanted plutonium isotopes. Just a few kilograms of this weapon grade plutonium is required for one nuclear weapon.
Adding to the proliferation risk is the growing stockpile of unirradiated plutonium (as opposed to plutonium contained in spent fuel), as reprocessing outstrips the use of plutonium in MOX (mixed oxide fuel containing plutonium and uranium) and its (negligible) use in fast neutron ‘breeder’ reactors. Unirradiated plutonium can be used directly in weapons or after simple chemical processing, and is therefore of greater proliferation concern than plutonium in spent fuel (which can only be separated in a nuclear reprocessing plant).
As at December 2008, there were 256 tonnes of civil unirradiated plutonium − increasing at an average annual rate of 7.9 metric tonnes since 1996.
All that would need to be done to address the problem of growing stockpiles of unirradiated plutonium would be to slow or suspend reprocessing until the stockpile is drawn down.