Office for Nuclear Regulation

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Dungess B - Planned Intervention

Executive summary

Purpose of intervention

This is a planned inspection at EDF Energy Nuclear Generation Ltd's (NGL's) Dungeness B (DNB) power station, undertaken as part of the planned intervention strategy for the Civil Nuclear Reactor Programme (CNRP) of the Office for Nuclear Regulation (ONR).

Interventions Carried Out by ONR

In relation to Licence Condition 11 (LC11) "emergency arrangements" we (a team of four ONR inspectors) observed DNB Level 1 emergency exercise "ELK". This consisted of a briefing on 22 July 2014 and the exercise and a debrief on 23 July 2014.

In relation to Licence Condition 23 (LC23) "operating rules" I (nominated site inspector) considered two topics. The first was implementation of NGL's Safety Case Health Review (SCHR) process and the second was reactor shutdown cooling including repressurisation. The first topic was selected since it is a comparatively new process that aims to give a yearly overview of the adequacy of the entire DNB safety case. The second topic was selected to help define a potential future periodic shutdown related ONR intervention "Arrangements for reseal and repressurisation of open primary circuit".

I (nominated site inspector) attended the DNB HEalth and SAfety Committee (HESAC) on 25 July 2014 to observe the HESAC and to give a presentation "ONR's Legal Basis and How we Regulate".

I (nominated site inspector) had a routine meeting with NGL's internal regulator [Independent Nuclear Assurance (INA)], and undertook information gathering which included following up several incidents on the site.

Explanation of Judgement if Safety System Not Judged to be Adequate

Not applicable.

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

In relation to Licence Condition 11 the exercise scenario included challenging aspects of relocation of the gatehouse and the Emergency Control Centre. The briefing included feedback from NGL's internal regulator based on their emergency preparedness surveillance since the last Level 1 emergency exercise. The main insight from this was the need to formally capture lessons learned from all emergency exercises in NGL's Corrective Action Programme (CAP). During the exercise itself, overall ONR observed a strong performance in many areas and no major learning points were identified. NGL's debrief was considered to be open and challenging. I (nominated site inspector) will write a letter to DNB which compiles the good points and learning points arising from the ONR team. These points will then be captured along with NGL's own debrief points in NGL's CAP. Taking all these factors into account we assigned an Integrated Intervention Strategy (IIS) Rating of 3 (adequate) to LC11.

In relation to LC23 and the SCHR process, I raised actions for DNB to revise relevant LC compliance arrangements and to incorporate the initial (2013) reactor SCHR in NGL's document management system. The 2013 SCHRs for both the reactor and fuel route had been completed though and I considered them to be adequate. In relation to reactor shutdown cooling including repressurisation, I found a clear link between safety case requirements and station operating and maintenance instructions. Taking all these factors into account I assigned an IIS Rating of 3 (adequate) to LC23.

In relation to the HESAC, I considered the meeting to be effective and well run and to include appropriate challenge. The monthly safety report was good and there was positive encouragement to attend INA led rapid trend reviews during periodic shutdowns at other sites. My presentation was well received.

In relation to the other activities undertaken in this intervention, no key findings arose.

The licence conditions were inspected against ONR's published guidance requirements (as described in our technical inspection guides).

Conclusion of Intervention

From the evidence obtained during this intervention, no matters have been identified that are likely to have a significant impact on nuclear safety on the station at this time. Therefore, no additional regulatory action arising from this visit is considered necessary at this time.


The 2013 SCHR for the fuel route had been placed in NGL's document management system.