By John Stang
Holtec International and the U.S. Nuclear Regulatory Commission are scheduled next week to discuss scratches on canisters used in the company’s HI-STORM UMAX spent nuclear fuel storage system.
The public meeting is scheduled for 1 p.m. Wednesday at NRC headquarters in North Bethesda, Md. During the two-hour session, Holtec will “present technical details addressing scratching and abrasion issues associated with the UMAX certificate of compliance.”
The HI-STORM UMAX system is a combination of canisters and tailor-made system of modules for dry storage. It is a version of Holtec’s HI-STORM system that holds at least 52,500 used fuel assemblies in 1,025 casks at 34 dry storage sites across the nation, according to a 2018 Ux Consulting Co. report.
The upcoming meeting resulted from an August 2018 mishap during loading of a 100,000-pound canister of used nuclear fuel into a storage pad slot at the San Onofre Nuclear Generating Station (SONGS) in San Diego County, Calif.
Following SONGS’ premature closure in 2013, used fuel from its two last operational reactors has remained in wet storage for cooling. In 2014, plant majority owner and licensee Southern California Edison selected Holtec, a New Jersey-based energy technology company, to expand the facility’s on-site fuel storage pad to accommodate the additional material.
The cask for nearly an hour was unintentionally hung up on a shield ring 18 feet above the bottom of bottom of the storage slot. The incident led to a special inspection by the NRC, which last week said it planned to fine Southern California Edison $116,000 for two violations of safety regulations.
At the time of the incident, SCE and Holtec had moved 29 of 73 canisters from wet storage to dry storage via the HI-STORM UMAX system. The fuel movement remains on-hold pending NRC authorization to restart. No timetable has been set for that goal to be reached.
The interior of Holtec’s spent fuel canister has 37 long rectangular chambers that each hold up to 37 spent fuel assemblies.
Roughly one-third of SONGS’ spent reactor fuel was already held in 51 canisters in an on-site independent spent fuel storage installation. That radioactive waste is from the plant’s reactor Unit 1, which shut down in 1992.
During a March 28 meeting of the SONGS Community Engagement Panel, some members of the public raised concerns about scratches and abrasions on the canisters due to the tight fit between the casks and the storage slots.
“Even minor scratches can shorten the life of these canisters. The question is, how bad are the gouges? And since there is no method to find or repair the gouges, this is an unacceptable situation,” Donna Gilmore, founder of the watchdog group San Onofre Safety, said at the meeting.
In a separate email to the NRC, Gilmore wrote that the scratches and abrasions are due to a lack of precision in inserting the canisters into the tight-fitting storage slots. She said the inserted canisters should be inspected for scratches, with the scratched casks to be removed from the storage pad. She also called for casks to be redesigned.
According to the NRC, the scratches on canisters have shown up only at SONGS. Officials from NRC and Southern California Edison said at last week’s Community Engagement Panel meeting that scratches on the canisters don’t weaken them. However, the NRC officials also the scratches-and-abrasions issue should be analyzed more, which has led to Wednesday’s meeting.
Holtec declined to discuss the scratching and abrasions matter prior to next week’s meeting.
