SELLAFIELD’S LEGACY | ASSET MANAGEMENT
Above: Nuclear material from Dounreay has been added to Sellafield’s inventory
ONR issued an enforcement notice at the FGMSP facility
requiring replacement of an inadequate fire alarm and detection system. It said, “Given the degraded condition of these facilities, containment safety functions that fall below the standards expected, and their significant radioactive inventory, these facilities will remain in ‘significantly enhanced’ attention for nuclear safety for the foreseeable future.”
Progress in places There had been progress in several areas. ONR agreed to allow Sellafield to deploy a diver on a trial basis in PFSP bays 11 and 12. During the last 10 years, Sellafield has undertaken significant clearance work inside these two bays using a range of techniques. Good progress had been made, but the techniques have delivered diminishing returns. Sellafield completed the first dive successfully before the end of 2022 and completed the trial in March 2023 following several successful dives. The use of divers has allowed Sellafield to retrieve some of the remaining material from bays 11 and 12, which existing retrieval techniques were no longer able to do. The experience from deploying divers in the PFSP will help inform investigations into how divers might also contribute to the clean up and dewatering of nuclear ponds. Sellafield conducted active commissioning and subsequent retrievals from MSSS Compartment 10, starting in April 2022, making good progress against the planned waste retrieval rate. It has retrieved 19 skips of miscellaneous beta gamma waste and retrievals are ongoing. It also began visual inspection of packages containing mixed oxide residues in the Mox Demonstration Facility Lab L to inform final disposition, which was completed in June 2022. Sellafield is making further progress with the assembly of the second of the three silo emptying plants, SEP1. This is in preparation for full retrievals, which are currently planned to commence in late 2025.
Leak to ground ONR also assessed Sellafield’s responses to regulatory concerns associated with a leak to ground in the MSSS original building. This is an old facility, with historic leakage from a section of single layer containment dating back to the 1970s. Leakage had recommenced. In its report for 2019/20, ONR required Sellafield to
ensure effective management and mitigation of the leak and to review its safety case in this area. In July 2022, Sellafield provided the outcome of a review. ONR guidance states that, in rare cases, an identified
leakage and escape cannot be stopped as the required repairs are not technically feasible. This is the case for this leak. ONR said it had assessed the radiological risks to workers and the public arising from the current and postulated future leakage as low. But “Recognising the potential for leakage to continue for several decades until the bulk of waste is retrieved from the silos, the leak rate and levels of ground contamination will continue to be closely monitored and reported.” Sellafield has a programme of work associated with the leakage: inspectors identified some shortfalls with the future programme of work, which will be monitored. The ONR has increased its scrutiny of a programme of active commissioning and early retrievals from PFCS compartment 5. It granted permission for the programme in February 2022, but during the initial stages of active commissioning, an equipment failure required an extended recovery and repair period (although it had no radiological or conventional safety consequences). Active commissioning and early retrievals were due to restart in mid 2023. ONR will monitor this “until we have confidence in the facility’s ability to retrieve”. Sellafield Ltd is making progress in preparing for the
operation of a new facility, known as the Box Encapsulation Plant Product Store/Direct Import Facility (BEPPS/DIF), for long term storage of waste from MSSS and PFCS. ONR saw delays to inactive commissioning due to technical and
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