Because of the added secondary circuit, the total amount of structural material in the BN-600 is approximately 50 percent more than for the VVER-1000 (1000 MWe) light-water reactor.16 The estimated cost of BN-800 construction is $2.2-2.5 billion, approximately 11 percent greater than that of the standard VVER-1000 or costing approximately 40 percent more per kilowatt (KW).17 This higher capital cost and the higher cost of plutonium fuel relative to low-enriched-uranium fuel would make electricity from the BN-800 much more expensive than that from the VVER-1000.

Scientific problems addressed, solved and remaining

Most of the technical problems relating to fast-neutron reactors were solved through extensive experimental and theoretical studies performed during the first 40 years of the program. Various reaction cross sections were measured for neutron calculations (criticality, neutron flow distribution, reactivity effects, control-rod effectiveness, etc.). The results were replicated in a number of criticality experiments. The criticality of the BN-350 was predicted within 1 percent (198 fuel assemblies calculated versus 200 experimental). Control-rod effectiveness was estimated with less than 10 percent uncertainty and temperature and power reactivity coefficients with 15-20 percent uncertainty. The startup measurements on the BN-600 produced similar results. There has been significant progress towards the understanding of the swelling effects in steel from high neutron fluence (>1022 n/cm2).18 The behavior of liquid metals, particularly liquid sodium, was studied at a number of IPPE’s experimental facilities over 50 years. Practically all aspects were studied and the results explained theoretically. New requirements for nuclear safety promulgated after the Chernobyl accident will require additional study but will likely not raise new scientific obstacles.