Office for Nuclear Regulation

Follow up to no-break system based Inspection

Executive summary

Purpose of intervention

Following a system based inspection of the No-break supplies system at Dungeness B in January 2015, concerns were raised as to the clarity of maintenance instructions associated with Motor Generator maintenance. An ONR Issue was raised for the licensee to review the adequacy of the associated maintenance instructions and record sheets. This intervention sought to discuss the changes made to the document and ensure that the procedures were adequate.

Interventions Carried Out by ONR

The intervention was to ensure that the changes made to the documentation following the system based inspection were sufficient to ensure compliance with licence condition 28 – Examination, Inspection, Maintenance and Testing.

Explanation of Judgement if Safety System Not Judged to be Adequate

Not applicable.

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

I consider that the revised wording of the maintenance instruction and the associated record sheet make the process for identifying the depth of maintenance work to be performed and then recorded much clearer. Having discussed the licensee’s arrangements with maintenance team members, I consider that the instructions are now much clearer and better positioned to demonstrate LC28 compliance.

Finally, the knowledge of the equipment, the maintenance instruction and basic electrical machine theory demonstrated by the maintenance team gave me the confidence that the technicians had the necessary understanding to make the correct decisions.

Conclusion of Intervention

I consider that the changes made to the maintenance instruction and associated record sheet now make the decision making process on the extent of maintenance to be performed sufficiently clear.  As a result, the associated regulatory issue has been closed. No further regulatory action is required.