Final Results of the Bulgarian Research Contract 13801-R0 with Project Title: WWER-1000 Coolant Chemistry Improvement by Extended Fuel Cycles

Main objects of this presentation at the third Research Coordination Meeting on CRP FUWAC (Turku, Finland, September 2009) are: A. The coolant water chemistry and radiochemistry characteristics during the 15th fuel cycle of Unit 5 of Kozloduy NPP which is the first fuel cycle after the finalizing of step-by-step introduction of 235U higher enriched fuel, realized through implementation of advanced fuel assemblies TVSA with gadolinia doped uranium fuel. B. Final evaluation of the developed and implemented primary circuit water chemistry guidelines in WWER-1000 Units in Kozloduy NPP by the introduction of 235U higher enriched fuel, realized by application of solid neutron burnable absorbers (Gd2O3) together with the dissolved in coolant neutron absorber - natural boric acid. C. General conclusions about the main conditions ensuring problemmless passing of 1000 MWe Units (WWER-1000) of Kozloduy NPP to implementation of 235U higher enriched fuel, including avoidance of AOA onset. D. Information (in addition) concerning some results about the isotopes of antimony in the primary coolant of nuclear power reactors (WWER-1000) during operation- and shutdown- periods in Kozloduy NPP. E. Publications - 2007-2009.