Office for Nuclear Regulation

Inspection of the Structural Integrity (Steel) aspects of maintenance conducted during the 2014 Dungeness B Reactor 21 periodic shutdown

Executive summary

Purpose of intervention

This report records the findings of my intervention visit to Dungeness B Nuclear Power Station during the 2014 reactor 21 Periodic Shutdown. The intervention was undertaken to confirm the adequacy of the work conducted by the Licensee to comply with the requirements of Licence Condition 28, examination, inspection, maintenance and testing. I was accompanied on my visit by a second ONR (Office for Nuclear Regulation) structural integrity inspector.

Interventions Carried Out by ONR

I undertook on-site meetings and plant inspections with relevant staff from NGL and their contractors to determine the adequacy of the work being undertaken on Reactor 21 in complying with the requirements of Licence Condition 28. I concentrated on items I judged important to Nuclear Safety.

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

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

At the time of my visit the periodic shutdown was progressing to plan with only one potential significant issue which relates to the discovery of water ingress in the gas bypass plant rooms REB04 (the filter room) and REB05 (which houses the recombination units). This was an emerging issue at the time of my visit and will require appropriate resolution prior to reactor restart. Evidence suggests that this is not likely to affect restart but will have an effect on future outage inspection strategy. I will track this issue as part of my assessment of the reactor restart.

Conclusion of Intervention

I judged that Dungeness B nuclear power station personnel were conducting their inspections in line with the pre-periodic shutdown intentions documentations and were dealing adequately with any defects or anomalies found.

Subject to satisfactory completion of the issue identified with the water ingress in the gas bypass plant, I am content to support a Consent for restart of R21 following Statutory Outage 015.

Based on my intervention, I conclude that the licensee has performed the work to an adequate standard. I propose that an IIS rating of 3 is appropriate.

The actions placed during this intervention will be tracked via the Action tracker in place for Reactor 21 2014 outage. This ensures that all actions related to the outage are captured in one location. The Return to Service actions will be closed out prior to consent for re-start being granted. The non-return to service actions will be turned into a single level 3 issue which will be owned by the site inspector. The actions I placed during this intervention are: