By John Stang
The U.S. Nuclear Regulatory Commission said Monday it intends to fine Southern California Edison $116,000 for an August 2018 mishap in handling of used reactor fuel at the San Onofre Nuclear Generating Station (SONGS).
While it has 30 days to contest the decision, the California utility said it would pay the penalty. “Southern California Edison accepts the civil penalty assessed by the Nuclear Regulatory Commission (NRC) related to the Aug. 3, 2018, canister downloading incident at San Onofre nuclear plant. The event should not have happened and as the licensee we take full responsibility,” SCE said in a written statement.
Southern California Edison is the majority owner and NRC licensee for SONGS, a San Diego County nuclear power plant that closed permanently in 2013 after faulty steam generators were placed in its two operational reactors. In early 2018, the utility and contractor Holtec International began moving the reactors’ remaining used fuel from wet to dry storage ahead of the start of decommissioning. The project was originally scheduled for completion by mid-2019.
During one transfer on Aug. 3, a 100,000-pound canister became lodged on a shield ring in its storage slot and at risk for a nearly 20-foot uncontrolled drop. It took personnel nearly an hour to identify and correct the problem.
During a webinar on Monday, Linda Howell, deputy director for the NRC’s Division of Nuclear Materials Safety, said the federal agency was filing two major violations against SCE following a late-2018 special inspection of the incident.
The first was for the loss of redundancy in safety when the straps holding the canister bunched up, creating the risk of a sudden drop. That resulted from problems in operations, training, and procedures and led to the $116,000 fine as a Severity Level II violation, she said.
As the Holtec canister was ready to be lowered into place on the ocean-side storage pad, it was held by two thick straps — each capable of holding 113,000 pounds. This was a redundant safety feature in case one of the straps broke.
Two Holtec employees were working the mobile machinery used to lower the canister into place — an operator and a spotter. This was the first time those employees had performed the procedure. Supervisors and all other personnel were 150 feet away to avoid unnecessary exposure to radiation. The supervisors could not properly see what was happening.
The spotter was out of position and the operator did not properly watch his instrument panel. The canister went slightly off-target while entering the below-ground slot, hanging up on the shield ring rather than slotting into place. Meanwhile, the machinery kept lowering the two straps.
The second violation was the three-day delay in informing the NRC. The incident occurred on a Friday. The agency should have been notified within 24 hours, but did not receive informal notice by telephone until Monday. A report that should have been filed within 24 hours was not submitted to until Sept. 14. The NRC and SCE have said the long delay was due to the utility’s different interpretation on the timeline to formally inform the federal agency about the incident.
No fine was levied for this Severity III violation due to the lower classification of severity and because SONGS had no significant violations in the previous two years, according to NRC officials.
Since Aug. 3, SCE has increased the size of the on-the-spot crew inserting the canister into the storage pad from two to 10; added monitors to ensure tensions on both landing straps; added a quality assurance manager to the fuel movement program; installed low thresholds for to stop work for safety reasons; improved training; upgraded procedures to include covering as many scenarios as possible; and conducted numerous fuel-transfer practice runs with dummy canisters.
The NRC also confirmed SCE’s studies that a canister can fall 25 feet without cracking.
In total, Southern California Edison responded to the incident with 71 corrective actions and nine corrective actions to preclude repetition, according to this week’s NRC presentation. The agency said it identified weaknesses in some of the areas. For example, in procedural changes, the waste canister downloading method did not have contingency steps in case of equipment failures and did not have a comprehensive criteria for freezing operations.
Southern California Edison still has work to do regarding scanning some of the canisters for scratches made as they were placed into storage, even though the NRC has concluded the scratches don’t translate to leaks in the canisters. The NRC will review SCE’s analysis of the canisters’ scratches before green-lighting a restart of fuel movement.
At the time of the incident, SCE and Holtec had moved 29 out of 73 canisters from wet storage to dry storage. The fuel movement won’t begin until the NRC approvals are done. No timetable has been set for that goal to be reached.
Decommissioning of the two reactors, by an AECOM-EnergySolutions venture, is scheduled to begin this year and conclude in 2028. It is anticipated to cost $4.4 billion.
