Office for Nuclear Regulation

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EDF Energy Nuclear Generation Limited (NGL), Barnwood - Probabilistic safety analysis (PSA) level 4 meeting

Executive summary

Purpose of intervention

The purpose of my intervention was to maintain a shared understanding of EDF Energy Nuclear Generation Limited's (NGL) probabilistic safety analysis (PSA) programme and prioritised work focus for both the advanced gas-cooled reactor (AGR) PSA programme and the PSA activities of the Fuel Route Systems Branch (FRSB).

Interventions carried out by ONR

I attended a level 4 meeting to discuss developments in AGR PSA. This is part of a wider NGL PSA intervention, as outlined in the ONR Intervention Project Records (IPR): NGL-038, 'Development, use and maintenance of PSA within NGL' and NGL-136 on fuel route PSA.

I considered the developments of the AGR PSAs in relation to Licence Condition (LC) 23 (Operating rules), adequacy of the safety case, consistency with ONR Safety Assessment Principles (SAPs) (SAPs FA.10 to FA.14 in particular) and ONR Technical Assessment Guide (TAG) 030, PSA.

Explanation of judgement if safety system not judged to be adequate

Not applicable as this was not a safety system inspection.

Key findings, inspector's opinions and reasons for judgements made

Most AGR reactor PSA models have reached a common standard, consistent with NGL's short term PSA strategy, and are now in normal maintenance and development as per NGL's living PSA process. In general I identified no significant concerns with the ongoing AGR reactor PSA programmes. Notwithstanding this, it is noted that the Heysham 1 and Hartlepool PSA models still require further development. NGL plans to address this for reactor faults by the end of 2015, but there still remains a potential gap for hazards. Two actions were agreed in relation to the Heysham 1 and Hartlepool PSAs that are captured as level 4 issues on ONR's issues database. I will continue to maintain oversight of the development of the Heysham 1 and Hartlepool PSA models as part of my ongoing NGL PSA intervention.

For the AGR fuel route PSAs, no significant changes in scope of the PSA programme were noted compared with previous interactions. This remains consistent with NGL's fuel route PSA strategy. I am content with these initial steps, but would ultimately expect further enhancements to be considered such as potential integration with the reactor PSAs. However, there appears to be regular slippage in the fuel route PSA programmes for all the AGRs. Progress with the fuel route PSA developments and the longer term strategy are to be discussed at a joint ONR / NGL PSA workshop being planned for mid 2014.

I provided feedback to NGL on preliminary findings following PSA inspections at Torness, Barnwood, Dungeness B and Hartlepool. NGL agreed to review these at its PSA Working Group and PSA Governance meetings, and these findings will be a topic for discussion at a joint ONR / NGL PSA workshop being planned for mid 2014.

Conclusion of intervention

I consider this was a useful intervention, with NGL providing a good overview of work carried out to develop the AGR reactor and fuel route PSAs in 2013 and the planned work in 2014. It is clear that a significant amount of work has been carried out and most reactor PSAs, with the exception of Heysham 1 and Hartlepool, have reached a common level consistent with NGL's short term PSA strategy. This stable position is positive.

Notwithstanding that most reactor PSAs have now reached a stable position, and should have addressed findings from the last periodic safety reviews, it is now important for NGL to consider whether this stable position is adequate and what the PSA focus should be in the longer term.

It appears that a lot of effort is going into the fuel route PSA programme. However, given the regular slippage in the programmes, NGL should ensure it is initially addressing the most risk significant areas. This aspect is to be discussed with NGL during a PSA workshop planned for mid 2014.