BN-800: Spent Fuel Dose Rates and the Plutonium Management and Disposition Agreement

ABSTRACT In 2000, Russia and the United States signed the Plutonium Management and Disposition Agreement to dispose of 34 tons of declared excess weapon plutonium each. A 2010 amendment allows Russia to dispose of its weapon-grade plutonium as MOX fuel in its BN-600 and BN-800 fast reactors with the condition that 30 years after irradiation the spent fuel must still emit at least one sievert per hour. Using depletion simulations for the BN-800 reactor, this note presents dose rates for fuel and blanket materials after different irradiation and cooling times. After the full irradiation time of 420 days, the fuel fulfills the disposition criteria. This is not true for shorter irradiation times, however. Furthermore, the dose rate from blanket elements, which breed weapon grade plutonium, declines even more quickly after irradiation. For some blanket element positions, the spent fuel standard is not fulfilled after 960 days of irradiation. To provide confidence in the agreement, Russia, the United States and the International Atomic Energy Agency should agree on monitoring of reactor power and irradiation times for plutonium disposition in such fast reactors.