Apart from the other excellent answers, there just isn't that much fissile material there. The amount required to fuel a bomb is significantly less than the am

Apart from the other excellent answers, there just isn't that much fissile material there. The amount required to fuel a bomb is significantly less than the amount required to fuel a power reactor - it simply wouldn't be economical to recover the fissile material, purify and downblend it. Note that there is a separate program that takes excess weapons HEU from Russian stockpiles and downblends it for sale as nuclear fuel. This is the "Megatons to Megawatts" program, and it has downblended almost 500 tons of HEU since 1995.