Office for Nuclear Regulation

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System Based Inspections (SBI) at Sellafield

Executive summary

Purpose of Intervention

The Office for Nuclear Regulation (ONR) undertakes all regulatory interaction with the Sellafield site licensee (Sellafield Limited, SL) against a strategy defined by the ONR Sellafield Sub Division.

In accordance with that Strategy, a system based inspection (SBI) of the glovebox ventilation system within the Magnox Reprocessing facility (MRF) was planned for November 2017. The purpose of this planned inspection was for ONR to confirm the adequacy of implementation of the licensee's safety case claims in respect of this system.

As part of each SBI, ONR examines evidence of the adequate implementation of six pre-defined licence conditions. These licence conditions (listed below) have been selected because of their importance to nuclear safety, and are defined within the ONR's formal process for delivery of an SBI

Interventions Carried Out by ONR

I led a two-day, on-site, SBI of the glovebox ventilation system within the Magnox Reprocessing facility (MRF), which is part of the Magnox OU. The inspection comprised discussions with SL staff, plant walk downs and reviews of plant records and other documentation.

Explanation of Judgement if Safety System Not Judged to be Adequate

The glovebox ventilation system was judged to be adequate.

Key Findings, Inspector's Opinions and Reasons for Judgements Made

From the evidence examined during this inspection, I consider that SL has adequately implemented those claims within the facility safety case that I sampled.

As part of the scope of this SBI, I considered if the related facility safety case might require an ONR assessment of adequacy in a timeframe shorter than currently planned. Although the safety case documentation is structured in a manner that does not always allow efficient extraction of information by the operator, based on the evidence sampled I have no reason to recommend an early assessment of the safety case for this system.

During this inspection, I reviewed evidence of adequate training against the system function. Additionally, I sampled a range of maintenance activities for components across the system and consider that, in all cases, SL provided adequate evidence of asset maintenance and inspection.

However, during the inspection, I identified four regulatory findings where either there was a shortfall against regulatory expectations or where SL could not provide evidence during the inspection period to demonstrate adequate implementation. I raised ONR Regulatory Issues (RI) to track SL's response to addressing the findings. There was one level 3 RI and three, less significant, level 4 RIs.

The level 3 RI related to a loss of oversight, resulting in delay to implementation of changes to check sheet reference values for glovebox depressions to allow adequate system health monitoring. SL management had lost track of the status of the changes and believed on-plant implementation was complete. This resulted in a loss of situational awareness and an oversight in raising a condition report against a glovebox where the depression was outside operational norms. I judged that there was no direct radiological risk to an operator, as thorough prior-use checks, as specified in operator instructions, would ensure that no one intending to use a glovebox could be contaminated.

The three level 4 issues, though of lower significance, were raised to track SL's actions against the findings and allow further intervention, as necessary.

Additional observations were provided to SL that I did not judge required follow-up. These will be followed up by SL's internal regulator and no additional ONR oversight is judged to be necessary.

Based on the sampled evidence, I consider that a rating of Green (no formal action) is merited for Licence Conditions 10, 23, 27, 28 and 34. For Licence Condition 24, I consider that a rating of Amber (seek improvement) is merited, as delays in the implementation of changed standards designated to monitor glovebox system health through recording depressions led to a loss of situational awareness of a degradation in the condition and related function of some of the system components. Whilst this did not result in an increased risk to operators, this was not to the standard I, or the licensee, expects. SL responded immediately to the finding, during the inspection, with a temporary remedy; however, the ONR regulatory issue will remain open until the actions are fully completed.

Engagement on Magnox Reprocessing Post Operational Clean Out (POCO) LC35

I engaged with the MRF POCO team to gain an overview of SL's preparations to enter POCO, planned to start in 2021. There were no regulatory findings to report from the meeting. I have a planned LC35 inspection in February 2018 and will formally consider progress against regulatory expectations at this time.

Conclusion of Intervention

From the evidence sampled during this inspection, I judge that the licensee has implemented adequately the sampled claims within its safety case. Additionally, on the basis of the evidence requested and reviewed, I consider that the licensee's formal arrangements for compliance with Licence Conditions 10, 23, 27, 28 and 34 are also being implemented adequately, but that a shortfall in compliance has been identified against Licence Condition 24. ONR Regulatory Issues were raised to follow-up SL's action to deliver improvements to remove the shortfalls.