“Multiple performance deficiencies” contributed to a mishap in transfer of spent reactor fuel at the San Onofre Nuclear Generating Station (SONGS) in California, and could have led to a storage container being dropped nearly 20 feet, according to initial findings from the U.S. Nuclear Regulatory Commission.
Agency personnel are investigating the incident, including a site inspection last month. “NRC
inspectors are continuing to review the licensee’s calculations of potential damage to the canister and the fuel from the misalignment and from a potential drop if the cask had fallen,” the agency said in a preliminary report posted online Friday.
SONGS majority owner Southern California Edison (SCE) in 2014 contracted Holtec International to move used fuel from reactor Units 2 and 3 at the plant, which permanently closed in 2013. On Aug. 3, a fuel canister was being placed into a below-ground slot in the oceanside storage pad. The canister’s rigging went askew so the container could not go smoothly into the silo, which took nearly an hour to fix.
Workers did not notice that the canister was not correctly aligned, that it was resting on a “divider shell assembly,” that its weight was not supported by lifting gear, and that the situation left the canister susceptible to a drop, the NRC said.
Preliminary findings, which the regulator said are subject to change, include: the incident led from SCE “deficiencies involving training, equipment, procedures, oversight, and corrective actions”; the event left the canister in an “unanalyzed condition” in which it could have dropped 18 feet; and the event was not reported to the NRC within the mandatory first 24 hours.
The fuel transfer has been suspended pending conclusion of the NRC probe.
“We understand there were some procedure and training issues, and some circumstances when persons were not adequately trained,” SCE spokeswoman Liese Mosher told the Orange County Register. “Overall, we do agree with what NRC is concluding and we’re looking forward to finishing up the discussions.”
