Conversion of lead-bismuth reactor technology: From NPS reactors to power reactors

Full text: Russia has gained unique experience in developing and operating reactor plants (RP) with lead-bismuth heavy liquid metal coolant (HLMC) as applied to power plants of nuclear powered submarine (NPS). At the beginning of the 50s the USA and the USSR almost at the same time started developing RP for NPS. In both countries the work was performed for two types of RPs - with water-cooled water-moderated reactors and reactors using LMC. In the USSR there was selected entectic alloy of lead and bismuth as LMC. Altogether eight NPSs with RP with lead-bismuth HLMC were built. The first prototype NPS of 645 project had two reactors. The rest of 7 NPSs of 705(705K) project had one reactor. Besides, there were built and operated two full-scale surface reactor bench-prototypes: in FEI (Obninsk) and in NITI (Sosnovy Bor). During the last period of time all principle problems were solved, which took place in developing RP with HLMC including problems of heat exchange and hydrodynamics, technology of coolant, corrosion and mass transfer, ensuring of radiation safety during operation with equipment polluted by polonium-210. Regulations for operation, issues of RP repair and reactor refuelling were optimized. RP life amounted to about 80 reactor-years. For commercial application a new nuclear power technology, not having analogues in the world practice, was demonstrated. At present the conditions are available for introducing this technology into civil nuclear energy. As a result of cooperative work performed by FSUE OKB 'Gidropress', GNC RF-FEI and the other organizations during last years, there was shown technical feasibility of creation of unified reactor module SVBR-75/100 with fast neutrons core and lead-bismuth coolant in the primary circuit, application of which will permit to realize a module principle in creating nuclear power complexes of different purpose and power. In developing SVBR-75/100 RP design there was accepted a conservative approach consisting in application of the primary and secondary parameters approved in practice and in maximum usage of approved fuel and structural materials and optimized principle decisions on equipment components and RP layout. Compliance with this principle decreases due date, scope and cost of R and D work, provides RP reliability and safety of its operation, decreases investment risk. This report deals with main structural features of RP with lead-bismuth HLMC and their evolution during conversion from NPS RP to RP for civil energy. (author)