Office for Nuclear Regulation

Reactor 22 Periodic Shutdown Structural Integrity inspection

Executive summary

Purpose of Intervention

This is a record of a planned intervention by the Office for Nuclear Regulation (ONR) at Dungeness B Power Station during the 2018 periodic shutdown of Reactor 22. The purpose was to inspect work by the Licensee, EDF Energy Nuclear Generation Limited, to comply with Licence Condition 28 (LC28), examination, inspection, maintenance and testing (EIMT).

Interventions carried out by ONR

I met with Licensee staff and their contractors to examine compliance with LC28. I concentrated on aspects of structural integrity that I judged important to nuclear safety. Documents associated with this inspection are stored in TRIM folder

Key findings, inspector's opinions and reasons for judgements made

I found satisfactory progress of planned EIMT by the time of my visit. Of 541 components in the programme, 148 were not started, 33 in grinding, 80 in progress, 18 in referral and 262 complete. I have  sampled aspects of the steam and feed systems, reactor internals, pressure systems safety regulations, pipe hangers and supports. I have found evidence of satisfactory EIMT for each of these.

I also sampled aspects of in-service inspection (ISI), flow assisted corrosion and corrosion management. For these I have three notable observations:

For the first two points, associated work by the Licensee was underway but not complete. I am satisfied that, at the time of my visit, the actions planned appear reasonable. I will consider their outcome in my assessment report. For the third point, I have been informed the next OAP meeting will address this matter and I will review the outcome, also in my assessment report.
I undertook a plant walkdown, in which I witnessed work by the Licensee to address corrosion of concealed systems. I noticed significant corrosion of seawater pipework, which runs outdoors in ducts that are normally covered and observed work underway to replace some corroded sections. I also observed the main steam pipe where cracking has been discovered. The component is located in a congested area of plant and access is somewhat difficult.


Based on evidence sampled, I conclude the Licensee has performed adequate EIMT to satisfy LC28. Based on ONR guidance, I award an inspection rating of Green. EIMT work planned by the Licensee during the periodic shutdown was not complete by the end of my inspection. I will monitor further progress and provide my judgement regarding return to service in my assessment report. In particular I will consider the adequacy of corrosion management, recovery actions following discovery of cracking in a main steam line pipe and plans for replacement of components where damage by FAC has been found.