By John Stang
Holtec International has requested a meeting with the U.S. Regulatory Commission to discuss two potential significant violations identified during a routine agency inspection in May of the corporation’s New Jersey headquarters.
The site visit from May 14-18 was intended to evaluate “the adequacy of Holtec’s activities” related to federal regulations on licensing for storage of spent nuclear reactor fuel, according to a Nov. 29 letter from the NRC to Holtec. Specifically, officials looked at factors that could have affected the March discovery of a loose pin in a spent fuel canister at the San Onofre Nuclear Generating Station (SONGS) in California.
The conference’s purpose is to help the NRC to determine whether the violations actually occurred.
In the letter last month, the industry regulator gave the energy technology company the choice of requesting a pre-decisional enforcement conference or alternative dispute resolution. A pre-decisional enforcement conference is a public discussion on the potential violations and mitigating circumstances that will lead to the NRC’s enforcement decision. In alternative dispute resolution, the NRC and Holtec would go into a closed session with a mediator to resolve the matter — with the result to be made public.
In a Dec. 3 response, Holtec President and CEO Kris Singh informed Michael Layton, director of spent fuel management at the NRC’s Office of Nuclear Material Safety and Safeguards, the company wanted to schedule a pre-decisional enforcement conference at a date convenient for the federal agency.
Singh wrote that there have been “misunderstandings and misperceptions” to date because Holtec has not been able to provide the NRC with important data regarding the March 5 event at SONGS. Also, Holtec wants to discuss its corrective actions with the NRC, he wrote.
“We appreciate the transparent and interactive process envisaged under the PEC, which we believe will help NRC reach well-founded conclusions as to the scope and severity of the violations … familiarize the NRC and our other stakeholders with the thoroughness of our completed and planned corrective actions aimed to preclude recurrence,” Singh wrote.
The NRC inspection found two possible semi-related violations at headquarters that could lead to “escalated enforcement” on top of a minor violation on the actual March incident, according to the Nov. 29 NRC report to Holtec. The minor violation was related directly to the loose pin. The more serious apparent violations address testing and engineering of the pins.
Holtec is the contractor for transfer of used reactor fuel from wet storage to dry storage at the retired nuclear power plant in San Diego County. That process has been on hold since an Aug. 3 mishap in placing a used fuel canister into the storage pad. Following a special inspection, the NRC has also identified two apparent violations in that incident. Holtec and SONGS license holder Southern California Edison hope to resume fuel transfers in January.
In the March 5 event, an aluminum pin broke off inside a recently designed cask used to store used nuclear fuel. Holtec subsequently switched to an older-design cask for fuel-moving operations at SONGS and the similarly shuttered Vermont Yankee nuclear power plant.
The interior of Holtec’s spent fuel canister has 37 long rectangular chambers that each hold up to 37 spent fuel assemblies. “Basket shims” are placed around the interior of a canister’s walls to keep the long rectangular chambers in place and enable circulation of helium used to cool the fuel assemblies. The broken pin was one of 88 in each canister to hold the shims in place.
In his letter, Layton said the Holtec quality assurance program failed to obtain an amendment to its NRC license prior to redesigning the canister with new shim specifications, which created the possibly of a malfunction with a result that would be different than its original safety analysis report. This is a Severity Level IV violation, which is minor.
However, the NRC inspection of Holtec’s headquarters found two apparent violations that could lead to fines or corrective actions, Layton wrote.
One apparent violation is related to several deficiencies in Holtec’s design control process on modifying the shims, Layton said. Holtec did not consider all the impacts of the shims’ changes on handling and manufacturing of some multi-purpose canisters “This design change affected three MPC types (37, 89 and 68M) and several general licensees because Holtec had delivered a number of systems to several purchasers,” Layton wrote.
Holtec’s design work on the shims did not address whether certain scenarios of external events on the canister could possible damage the fuel cladding, resulting in a possible release of radiation, the letter’s attachment said.
In a second apparent violation, Holtec assumed it did not need NRC approval for several design changes on the casks. The agency disagreed.
