VERNON — An expensive, time-sensitive effort to move Vermont Yankee's spent fuel into sealed casks has come to a halt as officials investigate a potential problem with those containers.
Spokesmen for plant owner Entergy and the federal Nuclear Regulatory Commission characterized the delay as precautionary. They said loose bolts were discovered in Holtec International's casks at a different nuclear site, and no problem has been identified at Vermont Yankee, which also uses that company's casks.
Though there is no date for resuming the fuel move, Entergy administrators say they're confident that the project will stay on schedule — without compromising safety.
"The campaign is on track to be complete by the end of 2018," said Joe Lynch, a senior government affairs manager for the company. "Safety is Entergy's most important value, and at no time has the safety of Vermont Yankee staff or the community been implicated."
Vermont Yankee stopped producing power in December 2014, and Entergy permanently removed all fuel from the reactor the following month. But all of the Vernon plant's radioactive spent fuel remains on site because of the federal government's failure to establish a national repository for that material.
The storage solution for the foreseeable future is to place spent fuel in concrete-and-steel casks manufactured by Florida-based Holtec.
Vermont Yankee had 13 loaded casks at the time of the plant's shutdown. The fuel-loading project, with costs expected to reach $143 million, includes the construction of a new storage pad and the transfer of the plant's remaining fuel from a cooling pool into 45 additional casks.
The project's timing is important. Getting all of the fuel into casks is a prerequisite for Entergy's proposed sale of Vermont Yankee to New York-based NorthStar Group Services. The sale is scheduled to close by the end of this year, pending regulatory approvals.
Entergy has 15 casks left to load, and it would seem there's quite a bit of wiggle room in the project's schedule: Plant administrators have said they can load and
move one cask in a week's time.
But the effort has been on hiatus since March 10 after "Entergy became aware of an issue with Holtec's spent fuel storage canisters at another site," Lynch said.
Neither Entergy nor the NRC identified that other nuclear site. A Holtec spokeswoman did not respond to requests for comment Friday.
Sheehan said a loose stainless steel bolt was found inside an unloaded cask at the unnamed nuclear facility.
While that may sound minor, the part plays an important role.
"The bolt attaches to one of multiple aluminum shims inside the cask that provides stability to the basket which houses the spent fuel and fosters the flow of helium to transfer heat from the fuel," Sheehan said.
That discovery "led to the subsequent identification of a bolt in a cask at the fabrication facility," he added. "Holtec is investigating why the bolts detached and any safety implications."
Sheehan said no loose bolts have been found at Vermont Yankee, and he noted that the plant's casks are "of a slightly different design."
"Nevertheless, out of an abundance of caution and to conduct further checks, Vermont Yankee has temporarily suspended its dry cask loading operations," Sheehan said.
It's not yet clear what might have to happen in order to get the project started again.
"Holtec and the Vermont Yankee team are in the midst of evaluating the issue, which will include inspections of the unloaded casks," Lynch said. "When fuel loading will resume is indeterminate at this time."
Sheehan said the NRC is monitoring the situation and communicating with both Holtec and Entergy.
"We had an inspector at (Vermont Yankee) this week who checked on the status of the issue," he said. "And we will have an inspector on site when cask loading operations resume."
Mike Faher can be contacted at firstname.lastname@example.org.