Office for Nuclear Regulation

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Reactor 4 Outage – Inspection of Graphite Integrity Aspects at Hinkley Point 'B'

Executive summary

Purpose of intervention

The purpose of this intervention was:

Interventions carried out by ONR

This inspection is one of a number performed by ONR during the periodic shutdown to determine if EDF Energy Nuclear Generation (NGL), the Licensee, has undertaken appropriate inspections in accordance with the safety case and maintenance schedule requirements.  This inspection focused on arrangements for graphite core examination, inspection and testing and the observations made during these periodic shutdown activities.

Key findings, Inspector’s opinions and reasons for judgements made

At the time of my visit, the licensee has completed 19 inspections out of target requirement of 31. There was nothing to suggest that the licensee could not meet the target requirements within the planned schedule.

Based on my questioning of the Licensee’s staff, I consider that those involved have had sufficient training to perform the various tasks relating to the graphite inspections.  I also examined some of the raw visual inspection data and I am content that it is of an adequate quality.

I have made a number of minor observations relating to the quality of the data, which I will pursue with the Licensee, but they are not sufficiently serious that ONR should delay the return to service.

I have a longer term concern about the adequacy of the Licensee’s methodology for distinguishing between cracks that have originated in the bore of the graphite bricks and ones that have originated from the keyway.  I will be pursuing this matter with the Licensee, but it should not affect the current return to service decision.

I saw nothing of significance to suggest that the adequacy of the graphite inspection activities would prevent a return to service. Therefore I have allocated an intervention rating of adequate.

Conclusion of intervention

I conclude that the Licensee has made an adequate start to a scheduled programme of graphite inspection.  A forthcoming assessment report will consider whether the results are consistent with the graphite safety case, once the inspection schedule has been completed.


I recommend that the relevant project inspector, who will be writing the project assessment report, considers my forthcoming assessment report on the same graphite topic in forming their decision as to whether to recommend that Consent to return to service is granted.