Thermo-chemical behavior of PHWR disassembled channel during severe accident condition: Numerical and experimental investigation

The postulated severe core damage accidents in PHWR can get initiated from limited core damage accidents incase moderator cooling is lost. Excessive sagging of the exposed fuel channels from moderator boil-off leads to channel disassembly. Steam reacts with fresh zircaloy at higher temperatures and generates hydrogen to a large extent. The present work investigates the effect of ingression of steam and associated hydrogen generation on a simulated disassembled channel for 220 MW(e) PHWR under postulated severe core damage accident conditions. The assessment of steam ingression in the disassembled channel at various inclination angles is carried out. The study shows that the inclination angle highly influences the ingression of steam, fuel channel temperature and hydrogen generation. The very low steam ingression for horizontal position of the channel was found to limit the Zr oxidation, while at higher inclinations angle, sufficient amount of steam ingression leads to higher hydrogen generation. (c) 2021 Elsevier Ltd. All rights reserved.