Executive summary
Date(s) of inspection:
Aim of inspection
The aim of this inspection was to verify that relevant work activities have been carried out in relation to C&I equipment and systems important to safety in order to confirm that it remains fit for its intended purpose at Heysham 2.
The inspection will also provide a contribution towards ONR’s regulatory decision as to whether a Consent, in accordance with LC 30 (periodic shutdown), should be issued to allow Heysham 2 to return to normal operating service.
Subject(s) of inspection
- LC28 - Examination, inspection, maintenance and testing - Rating: Green
Key findings, inspector's opinions and reasons for judgement made
Our inspection found that the commitments made in the Heysham 2 S12 R8 Outage Intentions Document for C&I equipment and systems important to nuclear safety have been satisfied for those elements of work complete at the time of the inspection. Our inspection of the work activities covered during this intervention has generally found that the workmanship applied was adequate and consistent with the standards expected from C&I suitably qualified and experienced persons (SQEP).
We reviewed many of the reactor safety systems and found these to be in good order and well maintained. We noted several areas of good practice, the ongoing relay exchange on the post trip sequencing equipment, a proposed extension to maintenance period, by the central technical organisation, for some equipment within the post trip sequencing equipment was considered to large a step and a more gradual approach has been adopted by station.
During shutdown, Heysham 2 had a failure of one of their variable frequency converters. An investigation found two faults, one associated with a circuit board and the second a relay.
Replacement of these items have been undertaken but we considered an area of good practice is the replacement of these items on the remaining variable frequency converters.
We did identify some areas for improvement in regard plant maintenance instructions to provide greater clarity of requirements and / or data recording but were minor in nature. In addition, we identified an area of good practice of relay testing in a number of reactor safety circuits but not in the Quadrant Protection. We have asked EDFNGL to justify why this is the case. We raised four actions which will be covered by a single Level 4 Regulatory Issue to track the progress of these.
Conclusion
From the evidence gathered during this C&I-based intervention, we consider that there are no significant matters that may impact on nuclear safety. We have not identified any significant issues in relation to the C&I equipment and systems that should prevent ONR from issuing a Consent to allow HYB to return to normal operating service.
Based on our inspection of C&I aspects of the HYB outage it is recommended that support be given for a Consent to allow HYB to return to normal operating service following successful completion of the planned maintenance activities in accordance with LC30.