Office for Nuclear Regulation

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Reactor 2 Outage - Graphite inspection

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) Torness (TOR) power station, in line with the planned inspection programme. This intervention is one of a number of LC28 compliance inspections performed by ONR during the periodic shutdown of TOR Reactor 2 (R2) to inform the ONR decision whether to issue a license instrument granting consent for the return to service of TOR R2 following its 2018 statutory outage.  This intervention specifically focused on arrangements for graphite core examination, trepanning and peripheral bricks.

Intervention Carried Out by ONR

I carried out an intervention at Torness on 1st October to examine NGL’s graphite core inspection arrangements with respect to LC 28 compliance. For this intervention, I was accompanied by an ONR graphite Principal Inspector. During our intervention, we focussed our attention on the inspection of the graphite core channels and of the peripheral bricks around the reactor. We requested information concerning the inspection findings and video monitoring of the fuel channels and of the peripheral bricks. We carried out a walkdown of the pile cap and examined the inspection equipment and the processes used for the inspection of the peripheral bricks.

Explanation of Judgement if Safety System Not Judged to be Adequate


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

At the time of my intervention, the licensee had completed the inspection of fifteen fuel channels out of sixteen. One of the fuel channels could not be inspected due to pile-cap valve access issues, but a reserved channel was planned for inspection during the periodic shutdown. During the outage, NGL plans to inspect eleven out of sixteen faces of the graphite peripheral wall around the core, including four of the faces having been inspected in 2015. At the time of my intervention, NGL had carried out the inspection of five faces of the peripheral brick wall. One face of the peripheral brick wall had already been inspected in 2015.

An assessment report will be produced subsequently to consider whether the work performed was sufficient and whether the findings are consistent with the current safety case. I have listed the key findings from this inspection below:

Conclusion of Intervention

Concerning the graphite core inspections, based on the sampling undertaken as part of this intervention, I did not identify any significant shortfall in NGL’s arrangements. I am therefore satisfied that the LC 28 arrangements in place are adequate and have been adequately implemented. The discussion with NGL staff was open and informative. A forthcoming assessment report will consider whether the results are consistent with the graphite safety case and make a recommendation with regard to the return to service of Torness Reactor 2.