Office for Nuclear Regulation

Heysham 2 - Reactor 8 2020 Statutory Outage - 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 intervention applicable to EDF Energy Nuclear Generation Ltd (EDF NGL) during the 2020 statutory outage of Reactor 8 (R8) at Heysham 2 (HY2) power station.  The main focus of this inspection was to inspect a sample of outage work activities carried out in relation to control and instrumentation (C&I) equipment and systems important to nuclear safety in order to confirm that they remain fit for their intended purpose at HY2 R8.

The intervention was planned in accordance with ONR’s Heysham 2 Integrated Intervention Strategy (IIS) for 2019/20.

Interventions Carried Out by ONR

The inspection covered a sample review of the HY2 R8 2020 statutory outage activities carried out in relation to C&I equipment and systems important to nuclear safety, and EDF NGL’s arrangements for compliance with LC 28 Examination, inspection, maintenance and testing (EMIT) and LC 22 Modification or experiment on existing plant. The outcomes of this inspection will contribute to ONR’s regulatory decision to grant Consent to the return of HY2 R8 to normal operating service in accordance with LC 30 (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.

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

This inspection has found that the commitments made in the HY2 R8 S11 outage intention scoping document (OID) (HB/REPS/OM065, Rev 001, CM 2019/222592) have been satisfied in relation to the sampled C&I equipment and systems important to nuclear safety.

Our inspection of the work activities covered during this intervention has 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 we noted that system engineers and maintenance technicians demonstrated a good knowledge of their respective systems and that good practices have been applied.  These included, trending of thermocouple behaviour, which led to an identification of an increase in degradation of the thermocouples and an engineering change to improve the design. In addition, the engineers demonstrated an adequate appreciation of the nuclear safety implications of equipment failures.  From a cyber security perspective, the station demonstrated improved control of portable computing devices entering the station and identified an area of improvement in the registration of portable computer devices on site.

During the plant walk-down, we found the plant areas and equipment cubicles inspected were clean and tidy, which provided evidence that Heysham 2 have followed good housekeeping practices. We also found examples of good ageing and obsolescence management that included a proposal to manage the ageing of the DPCS communication bus cables.

We also identified areas for improvement for the recording of test results for the reactor safety circuit end contactors.  We requested Heysham 2 to consider adding the range of contactor coil temperature in the plant maintenance instruction, when measurements should be taken and to clarify why the drop-off voltage is always at the bottom of the tolerable range.  We consider these are minor shortfalls and they do not have a significant impact on nuclear safety and are not required to be addressed prior to return to service.

During our inspection we sampled the implementation of two plant modifications relating to the latest software release for R8 data processing and control system and modifications to the half unit valves. We were satisfied that the implementation of these ECs was adequate and the station demonstrated due processes had been appropriately followed.

Based on the findings of our inspection of the C&I aspects of the HY2 R8 2020 statutory outage, we have assigned an integrated intervention strategy (IIS) rating of Green to LC 28.and LC 22.

Conclusion of Intervention

From the evidence gathered during this intervention, we judge 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 R8 at HY2 to restart.

On the basis of our inspection of the C&I aspects of the HY2 R8 2020 statutory outage, we recommend that support be given for a Consent to allow R8 to return to normal operating service.