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The final multi-purpose canister containing used nuclear fuel from the Pilgrim nuclear power plant in Massachusetts was placed in dry storage on 13 December, marking the removal of all fissile material from its reactor building. Holtec International said the operation - completed 30 months after the reactor was shut down - sets a new world record for the speediest transfer of a plant's used fuel to on-site storage.

The ISFSI at Pilgrim (Image: Holtec International)

The 680 MWe boiling water reactor at Pilgrim shut down on 31 May 2019 after 47 years of operation and was acquired by Holtec that August after the Nuclear Regulatory Commission approved the transfer of the plant's licence, including its existing dry cask used fuel storage installation. It was the second US decommissioning project to be acquired by Holtec, following Oyster Creek in New Jersey.

After the shutdown, Holtec loaded a total of 45 high-capacity HI-STORM 100 systems over two loading campaigns, with MPC-68 multi-purpose canisters. The Holtec team loaded 11 casks in the 2020 campaign and loaded an additional 34 casks during the final loading campaign that began in June and ended on 13 December 2021. In total, 62 HI-STORM 100 systems are now safely stored at Pilgrim's new Independent Spent Fuel Storage Installation (ISFSI), built at the plant site in 2020.

Holtec said to achieve the record transfer, its team had to design and build an innovative device to retrieve a severely damaged fuel assembly lodged in a fuel rack cavity since the 1970s that had thwarted all prior attempts to retrieve and containerize it. It added that the design and manufacturing know-how developed to extricate the legacy failed fuel assembly is now available to any nuclear plant facing the problem of retrieving a severely damaged fuel assembly.

This new record set by Holtec at Pilgrim improved upon a similar record-breaking defuelling - completed in 32 months - of Oyster Creek ibn May this year, the company noted.

"We hail the record-breaking defuelling of Pilgrim made possible by the leadership of Steven Soler, our Director of Domestic Site Services and Pilgrim Site VP John Moylan supported by a superbly trained team of craftsmen and technicians," said Holtec Decommissioning International President Kelly Trice. "We should also thank our inventive professionals in the Nuclear Power Division who devised a brilliant solution to delicately extricate a severely damaged fuel assembly lodged in Pilgrim's spent fuel rack, creating in the process a new technology to deal with damaged fuel assemblies."

Holtec said Pilgrim's used nuclear fuel will remain safely stored in the HI-STORM 100 dry casks at the onsite ISFSI until the US Government takes possession of it or the canisters are transferred to an alternative location, such as Holtec's proposed HI-STORE Consolidated Interim Storage Facility (CISF), which is undergoing licensing by the Nuclear Regulatory Commission. Final regulatory approval of the HI-STORE CISF is expected in early 2022. This facility, Holtec said, will provide "a supremely safe, secure, retrievable and centralised facility" for temporarily storing used nuclear fuel until its final disposal by the Department of Energy.

Researched and written by World Nuclear News

Date: Saturday, 18 December 2021
Original article: world-nuclear-news.org/Articles/Defuelling-of-Pilgrim-completed-in-record-time