STUDY WAYS TO INCREASE KW IN FAST REACTORS WITH MOX FUEL AIMING FOR THE MINIMUM OF SODIUM VOID REACTIVITY EFFECT

Abstract

This work presents the results of numerical studies on the possibility of increasing the maximum safe using different kinds of fuel for sodium-cooled BN reactors. The purpose of this work is to study and detect fuel or fuel combination with the best technical and economic indicators and safety conditions for the BN-800 reactor plant which not only increases the economic indicators but also the efficiency of the entire pre-reactor cycle. For some time now, the problems associated with a decrease in the amount of U235 resulted in an increase in price and an increase in the amount of accumulated Pu initially achieved in the military industry. However, since the reprocessing of spent nuclear fuel (SNF) by WWER and RBMK, ways must be sought to compensate for these phenomena with the priority of reliable and safe operation of a nuclear facility. An indicator of reliable and safe operation of nuclear power plants in the case under consideration is SVRE (sodium void reactivity effect). Achieving high values of this value leads to a decrease in the secure operation of NPPs and forces us not only to find ways to increase the RF, but also ways that result in minimal values for SVRE with maximum RF. In the calculations aimed at the reduction of SVRE it is assumed that the minimum value of KW is KW ≥ 0,95. The paper examines the effects of several important factors on reactor performance and economic performance. These factors include the use of different fuels and fuel combinations, the geometric dimensions of the reactor, the distribution of enriched fuel in the core, and the change in specific fuel volume within allowable limits. The influence of geometrical dimensions on the SVRE is considered, the size of the core is changed due to a change in the specific heat release and the volume fraction of the fuel. In the core fuel is introduced which nuclei have no spectral dependence on the amount of sodium.