Office for Nuclear Regulation

Torness Power Station, R1 2021 Statutory Outage: Control and Instrumentation (C&I) inspection

Executive summary

Purpose of Intervention

This Intervention Record covers my Control and Instrumentation (C&I) inspection performed as part of an ONR Operating Facilities Division (OFD) intervention applicable to EDF Nuclear Generation Ltd (EDF NGL) during the Reactor 1 (R1) Statutory Outage 2021 at Torness Power Station. The main focus 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 Torness. The intervention is intended to 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 Torness to return to normal operating service.

Interventions Carried Out by ONR

This inspection was undertaken in support of ONR’s 2020/21 statutory outage inspection programme. The outcome of this inspection, which included a review of progress made in various work items and projects associated with C&I equipment and systems important to safety at Torness, covered EDF NGL’s arrangements under Licence Conditions LC 22 (modification or experiment on existing plant), and LC 28 (examination, inspection, maintenance and testing).

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

Prior to my inspection and at the start of the outage Torness had experienced failure of a flux detector. There was already one failed flux detector which had been taken out of service and an installed spare ‘patched’ into the safety circuit. The general condition of a number of flux detectors is of concern. EDF NGL held an operational decision making meeting that concluded the need to replace two flux measuring assemblies. EDF NGL have entered their event recovery process to manage the current flux detector issues at Torness. On review of this outcome I agreed and supported this position and discussed the importance of achieving this before return to service with the Engineering Manager and Plant Manager.

During my inspection I found examples of good ageing and obsolescence forward planning and management. I also found the plant areas and equipment cubicles I inspected to be clean, tidy and free from foreign materials, which demonstrated that good housekeeping practices were being followed. The staff I talked to also appeared to have a good level of knowledge of the systems and equipment they were responsible for. One particularly noteworthy point was some proactive testing and learning from operational experience, on some main guardline trip units that had identified a failed unit. This could have resulted in a spurious trip if not identified. This led to the identification of other potential ‘at risk’ trip units that had been sent to the original equipment manufacturer for refurbishment.

My inspection found that the commitments made in the Torness R1 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. 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 my inspection I reviewed the implementation of some Engineering Changes that had been identified in EDF NGL’s Outage Intentions Document. These were, in the main, associated with the Quadrant hardening project, however, there were some additional modifications being undertaken to the Torness on-line computer system over and above the quadrant hardening related modifications. I considered the modifications and testing had been satisfactorily completed with the documentation and processes appropriately managed and signed off.

Based on my sample inspection of the C&I aspects of the Torness R1 2021 statutory outage I have assigned an intervention rating of Green to LC 22 and LC 28 compliance.

Conclusion of Intervention

From the evidence gathered during my C&I-based intervention, I consider that, EDF NGL are managing the exchange of two flux measuring assemblies and this can be monitored by ONR as part of normal regulatory business. I have not identified any other significant issues in relation to the C&I equipment and systems that should prevent ONR from issuing a Consent under LC30 to allow Torness R1 to restart following the statutory outage.

On the basis of my inspection of C&I aspects of the Torness R1 2021 statutory outage it is recommended that support be given for a Consent to allow Torness to return to normal operating service following successful completion of the planned maintenance activities in accordance with LC30.