Analysis of processes in spent fuel pools in case of loss of heat removal due to water leakage

Abstract

Paper presented at the 8th International Conference on Heat Transfer, Fluid Mechanics and Thermodynamics, Mauritius, 11-13 July, 2011.Safe storage of spent fuel assemblies in the facilities for intermediate storage (spent fuel pools) is very important. These facilities are not covered with a leak-tight containment, thus the consequences of overheating and melting of fuel in the spent fuel pools can be very severe. On the other hand, due to low decay heat of fuel assemblies, the processes in pools are very slow. Therefore, the accident management measures play a very important role in case of some accidents in spent fuel pools. This paper presents the analysis of possible consequences of fuel overheating due to the leakage of water from a spent fuel pool. Also the accident mitigation measure, i.e. the injection of water was evaluated. The analysis was performed for the Ignalina NPP Unit 2 spent fuel pool, using system thermal-hydraulic code RELAP5/MOD3 and the code for severe accident analysis ASTEC. The phenomena taking place during such accident are discussed.