Office for Nuclear Regulation

R1 025 Outage - Mechanical Engineering Inspection

Executive summary

Purpose of Intervention

The purpose of this intervention was to carry out licence compliance inspections at EDF Energy Nuclear Generation Limited’s Heysham 1 power station in line with the planned inspection programme contained in the Heysham 1 Integrated intervention Strategy for 2020/21.  This intervention is in support of the ONR decision on plant restart.

Interventions Carried Out by ONR

ONR Mechanical Engineering Inspector carried out inspections against the requirements of Licence Condition 28: examination, inspection, maintenance and testing to inform the ONR decision relating to the issue of a licence instrument for consent for return to service of Heysham 1 Reactor 1 following its periodic shutdown (Licence Condition 30).  The activities examined were selected due to their nuclear safety significance.

The intervention included:

Due to current Covid-19 related restrictions, a remote inspection was conducted.  The intervention was performed in line with ONR's guidance requirements (as described in our technical inspection guides) in the areas inspected.

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

Based on my sampling, I am satisfied from a mechanical engineering perspective that during the Heysham 1 Reactor 1 2020 (025) periodic shutdown:

During discussions on examination, inspection, maintenance and testing of the Secondary Shutdown System Nitrogen Injection Valves, I found that the level of knowledge of valve design varients and progress with an Engineering Change was not adequate.  I judged that this did not affect nuclear safety but was not to the expected standard.

Conclusion of Intervention

Based on my sampling undertaken as part of this intervention, I am satisfied that the Licence Condition 28 arrangements in place are adequate and have been adequately implemented with no significant shortfalls. I have therefore given this inspection an Integrated Intervention Strategy rating of GREEN.

From a Mechanical Engineering perspective, I would therefore support a request under Licence Condition 30 to return Heysham 1 Reactor 1 to operation following its 2020 (025) periodic shutdown.

I raised a level 4 regulatory issue related to visibility of configuration control of the Secondary Shutdown System Nitrogen Injection Valves and monitoring of the Engineering Change to modify these valves.