Office for Nuclear Regulation

Hunterston B - Control and Instrumentation inspection

Executive summary

Purpose of Intervention

This intervention record covers a planned inspection performed as part of an ONR Operating Facilities Division (OFD) intervention applicable to EDF Energy Nuclear Generation Ltd (NGL) during the 2019 statutory outage of Reactor 3 (R3) at Hunterston B (HNB) Power Station. The main focus of this inspection was to inspect work activities carried out in relation to control and instrumentation (C&I) equipment and systems important to safety in order to confirm that they remain fit for their intended purpose at HNB.

Interventions Carried Out by ONR

As an ONR specialist C&I inspector I undertook this inspection in support of ONR’s 2018/19 statutory outage inspection programme, accompanied by an external hazards nuclear associate. The inspection included a review of progress made with various work items and projects associated with C&I equipment and systems important to safety at HNB. It also covered EDF Energy Nuclear Generation Limited’s (NGL’s) arrangements for compliance with Licence Condition LC22 (Modification or experiment on existing plant), LC27 (Safety mechanisms, devices and circuits) and LC28 (Examination, inspection, maintenance and testing). Our inspection contributes towards ONR’s regulatory decision to grant Consent, to the return of R3 at HNB to normal operating service, in accordance with LC30 (Periodic shutdown).

The intervention was performed in line with ONR's guidance requirements (as described in our technical inspection guides) in the areas inspected.

Explanation of Judgement if Safety System Not Judged to be Adequate

Not applicable, no system based inspection was undertaken.

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

This inspection sampled engineering procedures and records for the HNB R3 outage, including maintenance inspections of C&I equipment and systems important to nuclear safety, and we carried out a walkdown of relevant plant. We found the work we sampled to be generally adequate. 

 We raised a low-category regulatory issue to ensure that we are kept informed of further work. Two aspects of this Level 4 Regulatory Issue relate to EDF Nuclear Generation Limited (NGL) providing further information from tests that have yet to be conducted. The third aspect of the Level 4 Regulatory Issue relates to NGL providing progress updates on actions requiring resolution following minor shortfalls identified during our plant walkdown. Whilst the return to service of R3 at HNB is not dependent on completion of these actions, it was agreed that HNB will provide some specific information to ONR before R3 return to service.

On the basis of our inspections of C&I aspects of the HNB R3 2019 statutory outage, we recommend that, from a C&I perspective, support be given for a Consent to allow R3 to return to normal operating service.

We found that relevant good practice was generally met with only minor shortfalls identified when compared with relevant guidance. Based on the findings of our inspection, we have assigned an intervention rating of ‘Green – no formal action’ for LC22, LC27 and LC28.

Conclusion of Intervention

On the basis of our sample inspection of the C&I aspects of the HNB R3 outage no issues were identified, from a C&I perspective, that should prevent ONR Consent for the restart of Reactor 3 at HNB, or that require regulatory action beyond routine engagements with the site.