Office for Nuclear Regulation

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Sellafield: B13 LTPR inspection

Executive summary

Purpose of intervention

This intervention is part of the Sellafield programme of inspections looking at Periodic Safety Reviews and specifically considered the B13 Long Term Periodic Review (LTPR). The facility is operated by NNL although Sellafield Ltd. (SL) are the Licensee. The emphasis of this intervention is on ensuring NNL bring the plant to an acceptable standard whilst continuing to operate the plant in a manner that maintains the plant risks as low as reasonably practicable (ALARP).

Intervention Carried Out by ONR

This inspection looked at compliance with Licence Condition (LC) 15 (Periodic Safety Reviews) and followed the lines of enquiry recommended in a fault studies scoping report namely:

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

This was a successful intervention with good cooperation between all parties. The inspection revealed that the submitted LTPR was below standard. This is recognised by NNL and suitable steps are being taken to address the gap.

The LTPR strategy adopted by NNL and agreed by SL was based on the standard Windscale practice to implement a new safety case. As such, NNL undertook a review to verify that the existing (2004) safety case would be adequate in the short term until the new safety case could be introduced, i.e. for the period up to the next Short Term Periodic Review (STPR) in December 2017.

In consequence, the LTPR was not a full review of the 2004 safety case because the new safety case should have re-baselined and replaced the existing safety case. However, a peer assist review of the new safety case in spring 2014 undertaken by NNL and facilitated by the SL Safety Case Improvement Team determined that the new safety case (2014) was not fit for purpose. In consequence, NNL have begun a programme of work to rewrite the new safety case. This left NNL/SL in the invidious position that they had to continue using the 2004 safety case after the Decision Date (DD) of 31 December 2014 (and probably until 2016).

The LTPR identified several Safety Significant Issues (SSI), and in particular the need to replace the Safe Operating Envelope (SOE) definition and associated operating instructions, and to update the engineering schedule and associated EIMT (examination, inspection, maintenance and testing) schedule. This work is ongoing and planned to be complete for the safety-critical elements by the DD. However, the SOE will be based on the 2004 safety case and so NNL will need to revisit this once the new safety case is implemented.

Thus although I consider the submitted LTPR to be below standard as it was undertaken on the premise that a new safety case would be implemented by the DD, I am satisfied that there would be little safety benefit in undertaking a full PSR at this stage as NNL have determined that a new safety case is necessary. I.e. I support the strategy being adopted by NNL and SL here. I also recognise that NNL/SL have taken appropriate action to maintain the safety case until the new case can be implemented, so I have awarded an IIS score of 4 (Below Standard) rather than a lower rating.

Conclusion of Intervention

In the circumstances, I am content that NNL and SL are taking reasonable steps to ensure the facility will continue to operate safely. There would be little safety benefit undertaking a full PSR at this stage as NNL have determined that a new safety case is necessary. In consequence, I requested that NNL undertake a further safety review when the new safety case is implemented to ensure they have suitable SOE and associated arrangements such as Operating Rules, Operating Instructions and maintenance schedules to ensure the facility operates within that SOE. This will be followed up in future regulatory engagements.