Safety evaluation of tunnel rack and dry well monitored retrievable storage concepts

This report discusses the safety evaluation of the dry well and tunnel rack concepts for the monitored retrievalbe storage of spent fuel assemblies from nuclear reactors and high-level waste from reprocessing plants. A list of initiating events that could have an impact on the safety of the facility was developed and screened for high-risk events. For both concepts, event trees and supporting fault trees were developed for the high-risk events; however, quantification of risk was performed only for the dry well concept. The results showed that transporter collision and canister drop accidents have the highest anticipated frequency of occurrence. These events are common to both concepts. The associated radiological release, however, is small. For the dry well concept, the seismic event leads to the most severe accident, but its frequency of occurrence is very small compared with the other initiating events evaluated. The expected risk to the US population from the operation of a dry well facility was found to be 1.2 x 10-2 latent cancer deaths per year in a population of 2 million around the reference site. 21 references, 19 figures, 14 tables