NRC: LOW-DENSITY PACKING, MITIGATION DECREASES SPENT FUEL RISK

The one-in-10-million-years chance of a severe earthquake causing a radioactive release from a spent fuel pool becomes even less hazardous when pools are packed to low density, and if mitigating measures are enacted after an incident, Nuclear Regulatory Commission staff told an internal agency review board yesterday.  A spent nuclear fuel storage pool like the one analyzed in this study—based on Exelon’s Peach Bottom nuclear plant in Delta, Pa.—has a 90 percent probability of surviving the severe earthquake modeled with no liner leakage, staff said to the Advisory Committee on Reactor Safeguards. And, “in the unlikely event that a leak occurs, spent fuel is only susceptible to a radiological release within a few months after the fuel is moved into the spent fuel pool. After that time, the spent fuel is cooled by air,” Project Manager for the study Don Algama said in the meeting yesterday. And, “Low-density packing in spent fuel pools would also decrease that percent.”

 

An NRC study, already sent to the commission and released for 30 days of public comment July 2, found that moving spent nuclear fuel out of pools to dry cask storage more quickly provides no additional safety benefit in the case of a large seismic event. The ACRS asked staff mainly about modeling scenarios for the seismic event, and asked about whether background cancer occurrences had been factored into radioactive release impact information. This study will inform a broader regulatory analysis of the spent fuel pools at operating U.S. nuclear reactors as part of Japan Lessons-Learned Tier 3 plan.