For decades, before they were shuttered, the nuclear power plants in Rowe and in Vernon, Vt., were closely and constantly overseen by inspectors of the Nuclear Regulatory Commission.
Similarly, the decommissioning of those plants follows rules and procedures dictated by the NRC to ensure the radioactive contamination that for the most part was contained for years within the plants doesn’t escape into our environment.
It would seem like human nature to let down your guard once a plant is closed, so we were glad to see the NRC is still keeping a close eye on the Vernon plant even as its high-level fuel waste is stored in casks ahead of dismantling.
We saw evidence of this diligence recently when the NRC filed a complaint against the manufacturer of radioactive waste storage casks used at the closed Vermont Yankee nuclear plant.
Holtec International adopted a design modification for its steel and concrete casks without federal approval.
NRC officials say the company made changes after discovering a loose “bolt” last March at San Onofre nuclear power plant in California. The small threaded posts connect to the bottom of shims within the casks to keep interior canisters containing fuel rods stabilized in each of the casks.
Despite its good intentions, the company apparently made the changes without appropriate NRC review.
Most of us couldn’t tell the difference between a lag bolt and a carriage bolt, but in nuclear engineering, even something as innocuous sounding as a “bolt” or “post” can be crucial if you are trying to contain highly radioactive spent fuel rods for hundreds of years.
As a result of the NRC discovery, the Vermont Yankee plant — where 58 casks are now stored following the reactor’s shutdown four years ago — temporarily halted transfer of those casks from its spent fuel pool. The transfer was resumed after two months of inspections to determine there was not a problem with the Vernon casks.
NRC spokesman Sheehan said Holtec altered the cask design without a written evaluation, contrary to federal safety regulations.
According to the Nov. 29 NRC Special Inspection report, Holtec apparently “failed to establish adequate design control measures” in its process of reviewing suitability of alternative “4-inch stainless steel standoff pins … (that are) essential to the function of the fuel basket to maintain support and ensure that the shims stay elevated to allow airflow to the fuel assemblies” in the canister.
The other apparent violation, it noted, was the company’s seeming failure to perform a written evaluation to demonstrate that its design change did not require a designated certificate of compliance amendment.
So, the two “apparent violations of NRC requirements” are being considered for enforcement action.
Holtec is scheduled to take part in a pre-decision enforcement conference Jan. 9 to provide additional information to federal regulators. The conference will help regulators determine whether a violation occurred as well as its significance and the need for any corrective actions.
When the Vernon plant was operating, it posed a potential danger to the entire region, should there have been an accidental release of radioactivity. After its dismantlement, its spent fuel will remain on site until a permanent national fuel dump is built, which could be decades away or longer. In the meantime, if something happened that would cause those casks to leak radiation, it could be a serious, long-term environmental problem. So it’s imperative the storage casks be designed and built, and perhaps modified, with our long-term safety and health in mind.
It sounds like that’s what Holtec had in mind when it changed the bolt design and what the NRC is trying to ensure with its action. We hope both keep doing their jobs, but by the book.