Executive summary
Date(s) of inspection
- February 2026
Aim of inspection
This inspection reviewed the adequacy of the arrangements in place at site for operating rules and instructions, focusing primarily on the role played in the reactor trips at HYB, and the subsequent learning that has occurred across the fleet related to the inspection sample.
Subject(s) of inspection
- LC23 - Operating rules - Rating: Amber
- LC24 - Operating instructions - Rating: Amber
Key findings, inspector's opinions and reasons for judgement made
The inspection sampled safety events, the associated Operating Rules (e.g. Technical Specifications) and Operating Instructions (e.g. Station Operating Instructions (SOIs)) as well as materials from subsequent investigations (e.g. ACINs and SACIs) to understand the role of EDF’s LC 23 and 24 arrangements played, and how the resulting corrective actions have mitigated vulnerabilities. The inspection involved interviews with representatives at Heysham B who are responsible for operating rules (Nuclear Safety Group), operating instructions (Operations department) and organisational learning (performance improvement), as well as discussions with the LC and process owners at the corporate centre.
The inspection sample identified shortfalls in arrangements for Operating Rules and associated Operating Instructions, to ensure that limits and conditions identified in the safety case are complied with at all times. The inspection identified systemic inadequacy of the governance and tracking of corrective actions associated with LC23 and 24 arrangements. For example, after safety events associated with Tech Spec compliance, actions to update Tech Specs and procedures were not always completed as intended by the initiating investigations.
Conclusion
ONR judged the findings of the inspection to be a significant shortfall in compliance with the expectations of LC23(3) and 24(2), which could have an impact on nuclear safety. Therefore both LC23 and LC24 were rated Amber. The inspection also identified shortfalls in event causal analysis and actions (LC7), these were less significant and an existing regulatory issue will be used to track follow up.
In follow up a level 3 regulatory issue (RI) has been judged to be the appropriate level of enforcement. An RI has therefore been raised to bring about improvement in EDF Heysham B LC23 and LC24 compliance arrangements with respect to implementation and governance of revisions to operating rules and instructions.