Executive summary
Purpose of Intervention
The Office for Nuclear Regulation undertakes all regulatory interactions with the Sellafield Site Licensee against a strategy defined by the ONR Sellafield, Decommissioning, Fuel and Waste Division. The strategy requires inspections to be performed against Licence Condition 15 relating to Periodic Safety Reviews, which requires the licensee to make and implement adequate arrangements for the periodic and systematic review and reassessment of safety cases.
The purpose of this intervention was for ONR to assess the adequacy of the B277 Periodic Safety Review and to ensure that Sellafield Limited is taking the necessary steps to continue to operate and maintain the plant in a manner that ensures that the plant risks are as low as reasonably practicable.
The three broad objectives of this intervention were to:
- Gain confidence that Sellafield Limited has undertaken an adequate Periodic Safety Review; accounting for lessons learnt and future foreseeable challenges.
- Gain confidence that the extant facility arrangements and the safety case are suitable and sufficient, and mitigate shortfalls awaiting improvements.
- Establish if Sellafield Limited has credible resolution plans to implement improvements identified by the Periodic Safety Review.
The inspection also provided an opportunity for ONR to gather information on the condition of B277 and the contribution that the plant makes to ONR’s strategic priority at Sellafield of high hazard risk reduction.
Interventions Carried Out by ONR
On 30th June & 1st July 2021, ONR carried out a one-and-a-half day inspection of Licence Condition 15 compliance relating to B277. The ONR inspection team was assembled following the submission of Sellafield Limited’s Periodic Safety Review, and consisted of:
- Nuclear Liabilities
- Mechanical Engineering Safety Inspector
- Civil Engineering Safety inspector; and
- PSR Project inspector
The intervention involved:
- Sampling the process and technical aspects of the application of Sellafield Limited Periodic Safety Review arrangements and associated documents.
- Discussions with appropriate members of Sellafield Limited staff with reference to the identified lines of inquiry.
- An inspection of B277 and associated structures, accompanied by the Safety Case Manager, two System Engineers and SL’s internal regulator.
The following ONR guidance was utilised as part of the inspection:
- NS-INSP-GD-015, Revision 5, Periodic Review.
- NS-TAST-GD-050, Revision 8, Periodic Safety Reviews (PSR).
- ONR Safety Assessment Principles (SAP), Rev.1
Explanation of Judgement if Safety System Not Judged to be Adequate
This was not a system-based inspection; therefore, no judgement has been made on the adequacy of the implementation of any specific part of the safety case.
Key Findings, Inspector's Opinions and Reasons for Judgements Made
Based upon sampling of submitted documents, discussions with Sellafield Limited staff and the plant inspection, ONR considers that Sellafield Limited has met the requirements of Licence Condition 15 with an adequate periodic safety review of B277.
ONR considers that:
- SL has undertaken an adequate PSR, which accounts for lessons learned and foreseeable future challenges.
- Arrangements to address the actions identified during the PSR are adequate.
ONR inspectors made the following observations about the PSR process:
- A possible improvement related to review of hazards associated with updated site flood model during the past PSR cycle.
- Facility review and closure of shortfalls. The ‘Boundaries and interface’ document required updating from short term periodic review in 2014. This will be addressed by updating the ATLAS condition report for post implementation review of Safety Case for removed drum monitor.
During the inspection, ONR identified a shortfall not related to LC15 compliance, resulting in a level 3 Regulatory Issue (RI 8848). The shortfall against Licence Condition LC28 relates to the condition of the containment structure and a proportionate enforcement action will be applied.
Conclusion of Intervention
Based on the evidence sampled during the inspection, ONR considers that SL has effectively implemented its arrangements for compliance with LC15. ONR therefore judges that an inspection rating of Green (no formal action) is appropriate for compliance against LC15 (periodic review).
ONR raised a level 3 regulatory issue related to a breach of implementation of LC28 arrangements for the containment structure. This encloses a contaminated control area of highest level of classification as per site arrangements.