Office for Nuclear Regulation

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Hartlepool R2 Statutory Outage - Graphite Integrity

Executive summary

Purpose of intervention

The purpose of this intervention was to undertake a Licence Condition (LC) 28 compliance inspection at EDF Energy Nuclear Generation Ltd's (NGL's) Hartlepool power station, in line with the planned inspection programme contained in the HRA Integrated Intervention Strategy (IIS) for 2015/16.

This intervention is one of a number of LC28 compliance inspections performed by ONR during the periodic shutdown of Hartlepool Reactor 2 to inform the ONR decision whether to issue a licence instrument granting consent for the return to service of the reactor following its 2016 statutory outage. This intervention specifically focused on arrangements for graphite core examination, inspection and testing and the observations made during these periodic shutdown activities.

Interventions Carried Out by ONR

I visited Hartlepool on 5 and 6 July 2016 to carry out an inspection of the work performed. The graphite activities during the periodic shutdown were progressing and the in-air inspections had just started that day. The New In-Core Inspection Equipment (NICIE2) and the Prototype Eddy Current Inspection Tool (PECIT) was being deploying. PECIT is a recent development in the inspection strategy so I was able to take the opportunity to observe its use.

I observed the use of the NICIE2 and PECIT equipment used in the graphite core inspections. I reviewed the quality of training records of operators and the quality of raw video data from the TV inspections.

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

Based upon my observations of the graphite inspections performed, including training, data quality and data analysis, there was nothing of significance that would prevent a return to service. However the graphite inspection and trepanning work had not been completed at the time of my visit and only provisional analysis had been performed on the findings. ONR will subsequently prepare an assessment report which will consider the results and make a judgement as to whether the findings are consistent with the licensee's safety case.

I drew two key findings from my inspection.

Firstly, the downward pass video footage obtained from the NICIE2 inspection equipment is a valuable source of visual information that provides a full annulus view of the channel at a given height. It is not formally part of the inspection data used in the data review. I recommend that the downward pass is now formally included in the inspection process. I support this with the visual confirmation it provided of the extent of "lipping-in" of the layer 7 brick in channel D09. Further support is provided from the recent Hunterston R4 periodic shutdown where the downward pass footage also assisted in identifying a crack which appears to have occurred during those specific inspection activities.

Secondly, the layer 7 brick in channel D09 was found to have the largest ovalisation observed fleet wide to date. This generates a potential ledging/snagging risk to free movement of fuel in this channel and may also present other challenges. These risks and challenges should be addressed in the return to service Engineering Change and will be reviewed by ONR in its assessment report on the results of the graphite inspection work.

Conclusion

Based on the sampling undertaken as part of this intervention, I am satisfied that the LC 28 arrangements in place are adequate and have been adequately implemented and I judge that the licensee is in an adequate position to complete its full scheduled programme of graphite inspections. I have therefore given this inspection an IIS rating of Green - adequate.

A forthcoming assessment report will consider whether the results are consistent with the graphite safety case, once the inspection schedule has been completed and make a recommendation with regard to the return to service of Hartlepool Reactor 2.