Full-core reactor physics analysis for accident tolerant cladding in a VVER-1000 reactor

Abstract

Abstract Advanced accident tolerant cladding materials have brought up the potential to delay the deleterious consequences of loos of coolant accidents related to slowing down hydrogen formation from reaction of zirconium with steam in order to minimize the additional heat generation and improve fuel and cladding retention of fission products. The performance improvement offered by these advanced materials may expand the operating envelope of existing light water reactors. This paper examines the neutronic performance of the VVER-1000 light water reactor for the application of accident tolerant cladding in order to realize the endurance of severe accident conditions. This study includes a detailed analysis of the control rod worth, reactivity coefficient, fuel cycle length, and power distribution for three accident tolerant cladding candidates of Ferritic-based alloy (FeCrAl), silicon carbide (SiC), and chromium coating application on zirconium claddings (ZrCr). The analysis was performed using diffusion-based core code PARCS, and lattice physics code DRAGON, including a developed package for regeneration of cross-sections in PMAX format. The reactor performance analysis indicates that the SiC cladding would have improved performance in terms of fuel cycle length, fuel and moderator temperature reactivity coefficients, and control rod worth. The cycle length would significantly decrease in magnitude for FeCeAl. Therefore, decreasing the cladding thickness by half and increasing the fuel enrichment by factor of 1.1875 made it possible to satisfy the required cycle length. A higher enrichment is also necessary for ZrCr cladding to increase the fuel burnup limits at nominal operating conditions.