Evaluation of accident tolerant cladding materials in a severe accident of the BNPP

摘要

Accident Tolerant Fuels (ATFs) are fuels or fuel dads with improved features in comparison with standard UO2-Zircaloy in commercial LWRs. The ATFs could tolerate in vessel loss of coolant accidents. Iron-Chromium-Aluminum (FeCrAl) alloy and Silicon carbide (SiC) are being introduced as enhanced cladding candidates to mitigate accident consequences. These cladding materials have slower oxidation kinetics and high resistance to core degradation which reduce hydrogen accumulation in severe accidents. This paper deals with the evaluation of ATFs in hydrogen mitigation during Station Blackout Accident (SBO). In this analysis, a numerical model based on MELCOR for Bushehr Nuclear Power Plant (BNPP) in SBO is prepared and replacement of ATF cladding materials (FeCrAl and SiC) is studied. The thermal hydraulic response of the BNPP and core heat-up with clad oxidations are evaluated and the hydrogen generation due to the pernicious interaction of hot steam and cladding materials for FeCrl, SiC and zircaloy-4 are calculated. The results show the total hydrogen accumulation in the SBO of the BNPP are reduced 68% and 47% for FeCrAl, SiC, respectively. The accumulated energy in the core are reduced 88% and 81% for FeCrAl and SiC, respectively and the debris generation and lower head failure are improved, significantly. The results illustrate the lower hydrogen generation and oxidation kinetics in case of using the ATF materials and the performances are demonstrated. (C) 2019 Elsevier Ltd. All rights reserved.