This intervention report covers my control and instrumentation (C&I) inspection performed as part of an ONR Operational Facilities Division (OFD) intervention applicable to EDF Energy Nuclear Generation Ltd (EDFNGL) during the 2018 statutory outage of Reactor 22 (R22) at Dungeness B (DNB) Power Station. The main focus of my 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 they remain fit for their intended purpose at DNB.
This inspection was undertaken in support of ONR’s 2018/19 statutory outage inspection programme. The outcome of this inspection, which included a review of progress made regarding various work items and projects associated with C&I equipment and systems important to safety at DNB, covered EDF NGL’s arrangements under Licence Condition LC28 (Examination, inspection, maintenance and testing). This inspection is intended to provide a contribution towards ONR’s regulatory decision as to whether a Consent in accordance with LC30 (Periodic shutdown) should be issued to allow R22 at DNB to return to normal operating service.
Explanation of Judgement if Safety System Not Judged to be Adequate
This inspection has found that the commitments made in the DNB R22 Outage Intentions Document (OID) 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. My 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).
During the inspection I experienced evidence of good practice and proactive work in regard to the relay replacement in the enhanced shutdown system and drive module replacement for the control rods. In addition, I witnessed proactive work to provide tooling and rigs to improve build quality of neutron flux detector assemblies. I also identified a number of occurrences where pass/fail criteria did not have a tolerance specified in the maintenance instructions leaving the acceptance somewhat subjective. I further noted that some thermocouple test documentation did not specify pass/fail criteria. Two actions were raised in regard of these items.
Work was still on-going at the time of my inspection and I have requested further test documentation when completed which gave rise to seven requests. Two actions were raised, one associated with Gas Circulator pressure switches pass/fail criteria tolerance and one on Boiler Gas Outlet Temperature thermocouples pass/fail criteria for insulation resistance being absent. None of these actions impact on the return to service of Reactor 22 at DNB.
Outstanding actions have been captured within the ONR Issues Database.
Based on the findings of my inspection I have assigned an integrated intervention strategy (IIS) rating of Green to LC 28.
From the evidence gathered during this intervention, I judge that there are no significant matters that may impact on nuclear safety. I 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 R22 at DNB to restart.
On the basis of my inspection of the C&I aspects of the DNB R22 2018 statutory outage I recommend that support be given for a Consent to allow R22 to return to normal operating service.