US Holtec International announced on 4 April that, following the defueling of the Oyster Creek and Pilgrim NPP used fuel pools, both facilities’ high-level waste parts have been loaded into Holtec’s HI-SAFE storage systems and securely stored at the respective sites.
Known as Greater-than-Class C (GTCC) waste, highly radioactive components within the facilities’ reactor vessels were remotely segmented and placed into the Company’s HI-SAFE storage systems. These are designed for low-dose- accreting storage of highly activated metal components and enabled Oyster Creek and Pilgrim to remove their activated components despite the unavailability of a viable disposal facility for this type of waste.
Oyster Creek was the first of the two sites to fully load and store its GTCC waste into four HI-SAFE systems. The final unit was filled and placed on the site’s Independent Spent Fuel Storage Installation (ISFSI) pad last August.
Pilgrim completed the placement of all its GTCC waste into three HI-SAFE systems earlier in March of this year, using best practices from Oyster Creek’s campaign, and by utilising an improved HI-SAFE systems design, Holtec said. “The improved HI-SAFE system introduced at Pilgrim is a piece of our relentless drive for minimising crew dose and maximising worker safety,” said Holtec’s Senior Vice President of Operations, PK Chaudhary.
The HI-SAFE system design is based on Holtec’s HI-STORM dry storage system for used nuclear fuel. The HI-SAFE system consists of the overpack that provides the requisite shielding and an internal canister that serves as the primary confinement boundary for the radioactive material. The system provides robust, low-dose interim storage of non-fuel waste.?The extent of shielding around the HI-SAFE storage system depends on the type of waste being stored.
Photo: A Canister Storing GTCC Waste Being Transferred to a HI-SAFE Storage System at Oyster Creek (Credit: Holtec International)