Office for Nuclear Regulation

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Inspection of Licence Condition 15 (periodic review of safety cases) in Pile 1 on Sellafield Ltd.’s nuclear licensed site at Sellafield, Cumbria

Executive summary

Purpose of intervention

This intervention is part of ONR’s programme of inspections of Sellafield Ltd.’s Periodic Safety Reviews (PSR) and specifically considered the Pile 1 Long Term Periodic Review (LTPR). The facility is operated by Sellafield Ltd. (SL) as the licensee.

Intervention Carried Out by ONR

This planned inspection examined compliance with Licence Condition (LC) 15 (the requirement to undertake Periodic Safety Reviews of the safety case). I followed the lines of enquiry recommended in the ONR fault studies scoping report and agreed during discussions with the inspection team prior to the visit to site. The intervention focused on SL’s review of the safety case in respect of the higher impact fault sequences.

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

This was an effective intervention and greatly benefitted from open dialogue and good cooperation between all parties. The inspection determined that SL had undertaken an effective, pragmatic LTPR which has resulted in the licensee identifying 16 gaps which could affect safety but there were no substantive safety case shortfalls. SL reported that 15 of the gaps have been addressed and the outstanding gap depends on the implementation of the active handling facility revised safety case which is not expected until the end of 2016. SL is also planning to implement revised Hazard Analyses (HAZANs) and transition from Windscale safety assessment methodology to SL methodology under a new safety case by, or shortly after, the decision date for this LTPR (29 June 2016).

Our inspection did not reveal any matters of substantive concern that had not already been identified and were being addressed by the licensee following its own review. The inspection did, however, identify three areas which SL should resolve and document when its Confirmation of Safety Letter (COSL) is submitted to ONR later this year, namely:

Confirmation that the secondary containment can adequately withstand extreme winds by reference to appropriate assessments.

Confirmation that SL has resolved the corrosion problem on the ventilation system which is due to water ingress into the building or has a credible plan to implement appropriate actions a timely manner.

Confirmation that the revised safety case has been implemented or there is a credible plan to implement the safety case in a timely manner.

In addition, the ONR inspection team identified a shortfall in the ATLAS arrangements in that there was an inadequate audit trail to support close out of some actions on the ATLAS database. This was raised with the safety case improvement lead who was present during the inspection and is part of ongoing discussions on the close out of LTPRs.

Conclusion of Intervention

Based on the limited sample examined, the ONR inspection team considered that SL has carried out an adequate Long Term Periodic Review (LTPR) of Pile 1. Through our discussions with SL of the higher impact fault sequences, the team established that SL has adequately considered potential improvements. Consequently, I have awarded an IIS rating of 3 (Adequate) against LC15.

As part of its LC15 arrangements, SL will produce a Confirmation of Safety Letter (COSL) to confirm the facility has adequately implemented the LTPR and that it considers risks have been reduced as low as reasonably practicable (ALARP). I have, therefore, raised a Regulatory Issue to capture the three areas for resolution mentioned identified above to provide visibility that they are adequately addressed in the COSL.