EXPERIMENTAL AND NUMERICAL ANALYSIS OF STACKED SPENT FUEL TRAYS SUBMERGED IN WATER POOL SUBJECTED TO EARTHQUAKE LOADING

摘要

The spent fuel bundles received from Pressurized Heavy Water Reactors (PHWRs) are stored under water in spent fuel storage facilities in stacks of 20 to 30 trays. The water depth ranges from 6-7 meters. To ensure the safety it is required that the trays holding the fuel bundles should not topple under Design Basis Earthquake conditions. This may be demonstrated either through experiments or using analysis procedures. Analytical procedures are not well developed accounting the sliding, impact and hydrodynamic effects. Hence initially experiments were performed on full scale two stacks of trays holding dummy fuel bundles submerged in water. Various response parameters such as hydrodynamic pressures, displacements of trays, accelerations of the tank wall were measured. It was noticed that 30 tray stacks could stand safely without toppling under design basis peak acceleration of 2 m/sec~2. Analysis methodology was simplified by carrying it out in three steps. In first step stacks were analyzed without considering hydrodynamic effects. In second step hydrodynamic behavior of water was evaluated considering appropriate boundaries of tank wall and stack. Then in third step analysis of stack was performed using hydrodynamic effects. The results obtained in first and third step was superimposed to get final response and compared with experimental values. It is shown that results compared well with the experiment.