Seismic analysis of submerged spent fuel storage structure

The purpose of this calculation is to provide structural integrity analysis for the loaded new spent fuel rack arrays against possible seismic excitation. The seismic design calculation is based on the UCRL-15910 spectrum with peak ground acceleration of 0.32g and 5% damping. This spectrum may be considered as an upper bound of the newly developed Oak Ridge site-specific spectrum with 0.29g peak ground acceleration and 5% damping. Both are more conservative than the current design basis seismic acceleration of 0.15g for HFIR. The calculation is carried out by using ABAQUS version 5.2 and the response spectrum option. Since the new racks are to be submerged in HFIR pool, the pool water induced virtual mass has been conservatively taken into consideration. The result shows that if the silo buckling is regarded as failure than, with 95% confidence, the 5% probability of failure ground acceleration is as much as 2.334g. As compared with the design basis of 0.32g, the structure is very safe against earthquake