- Site: Hunterston B
- IR number: 21-104
- Date: October 2021
- LC numbers: N/A
Executive summary
Purpose of Intervention
The purpose of this intervention was to provide regulatory confidence in the management of conventional health and safety hazards present at EDF Energy Nuclear Generation Limited (NGL) Hunterston B power station (HNB). Specifically, the Control of Major Accident Hazards Regulations 2015 (COMAH). The inspection is part of the annual intervention programme agreed with the facility.
The visit was led by the Office for Nuclear Regulation (ONR) as part of the Competent Authority (CA), to assess adequacy of COMAH regulatory compliance within defueling planning and preparation activities. The intervention also provided site familiarisation for the new ONR COMAH Inspector.
Interventions Carried Out by ONR
A site inspection was conducted on 21 October 2021 and the key regulatory activities undertaken are summarised below:
- Review control of hazardous substance inventory and projected substance reduction;
- Review arrangements for defueling planning and preparation, including incorporation of COMAH requirements;
- Inspect standard of COMAH substance bulk storage at HNB.
Regulatory judgement was based on determining compliance with the Control of Major Accident Hazards (COMAH) Regulations 2015 and Dangerous Substances and Explosive Atmospheres Regulations 2002 (DSEAR).
Explanation of Judgement if Safety System Not Judged to be Adequate
N/A
Key Findings, Inspector's Opinions and Reasons for Judgements Made
Provision of documentation in advance of the inspection and the informative presentation assisted CA in evaluation of COMAH management arrangements. CA was content the inventory of hazardous substances is being managed within COMAH lower tier threshold boundaries.
The inspection of HNB defueling planning and preparation activities revealed a structured approach to pending change. This is being driven primarily by NGL’s Defueling Preparation Board, based on plant system requirements, with specific changes managed by project teams within the engineering change modification process. Cognisant of nuclear safety and support system requirements, CA reflected positively that HNB will remove specific hazardous substances and associated Major Accident (MA) hazards at the earliest opportunity.
Through descriptions shared by HNB, CA is content COMAH major accident considerations are largely imbedded within centralised arrangements. CA look forward to receiving additional information as requested during the intervention.
CA was encouraged to receive a clear commitment from HNB regarding ongoing asset integrity management and also the maintenance of emergency response provision. Equally, CA is satisfied with the station’s approach to the status of redundant COMAH storage vessels, however advised the capture of this intent within a clear policy.
Based on discussion during the site intervention, CA reflected that the high-level oversight and ownership of the COMAH regime was unclear. CA would benefit from a more detailed illustration of the arrangements in place. Given the brief time available, CA will explore this issue in the future .
Hazardous substance storage and off-loading facilities were inspected during the plant walk down. Overall, good standards were observed, however, CA identified a number of issues including provision of tank level display, plant labelling and pipework marking, which were judged to be minor. Nevertheless, further investigation and corrective action is required, to which HNB have responded constructively. Regarding these matters, CA will monitor HNB progress with improvement action through existing Level 4 meetings / communication channels.
Conclusion of Intervention
A summary detailing inspection findings, verbal advice and document requests was shared with HNB at the close of the intervention.
An inspection rating of Green, no formal action has been assigned to this intervention.