Office for Nuclear Regulation

Dungeness B – Inspection ID: 22-037

  • Site: Dungeness B
  • IR number: 22-037
  • Date: May 2022
  • LC numbers: N/A

Executive summary

Purpose of Intervention

To provide regulatory confidence in the management of conventional health and safety hazards present at EDF Energy Nuclear Generation Limited (NGL) Dungeness B power station (DNB). Specifically, the Control of Major Accident Hazards Regulations 2015. The inspection is part of the annual intervention programme agreed with the establishment.

The visit was organised by the Office for Nuclear Regulation (ONR) as part of the COMAH Competent Authority (CA). The purpose is to assess adequacy of COMAH regulatory compliance regarding decommissioning planning activities and the removal of hazardous substances. The intervention also provided site familiarisation opportunity for the new ONR COMAH Inspector.

Interventions Carried Out by ONR

A site inspection was conducted on 26 May 2022 and the key regulatory activities undertaken are summarised below:

  • Review COMAH management system arrangements;
  • Review arrangements for decommissioning planning and preparation, including incorporation of COMAH requirements;
  • Review management of methane inventory removal;
  • Inspect standard of COMAH substance bulk storage at DNB, including pipework isolation.

Regulatory judgement was based on determining compliance with the Control of Major Accident Hazards (COMAH) Regulations 2015, Dangerous Substances and Explosive Atmospheres Regulations 2002 (DSEAR) and Control of Substances Hazardous to Health Regulations 2002 (COSHH).

Explanation of Judgement if Safety System Not Judged to be Adequate


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

The dutyholder communicated openly during the site inspection and provided documents in advance to support the demonstration of arrangements.  This assisted CA evaluation of management systems and hazardous substance removal activities.

It is CA opinion that hazardous substances are being managed within COMAH lower tier threshold boundaries and adequate inventory control arrangements are in place. CA highlighted the opportunity to review and update the major accident prevention policy, process hazard reviews, emergency response handbook and programme of emergency exercises, to reflect the recent changes. Overall, CA was content that removal of the majority of flammable gas inventory significantly reduced major accident hazard risk at the station.

CA judged the standards observed on site during the walk down to be adequate and highlighted areas in which good practice was observed. The walk down included a visit to the ammonium hydroxide storage compound, where CA discussed vessel corrosion observed. Whilst the issue had been identified by DNB, CA recommended a review of the maintenance work order and scheduling to ensure inclusion of pipework supports and timely completion. Tanker offload points within this compound were judged by CA to be vulnerable to vehicle impact. DNB were advised to review the hazard utilising a structured risk assessment process. CA will monitor progress with these issues through existing communication channels.

During the walk down minor shortfalls identified by CA were brought to the attention of the dutyholder, who responded positively. CA understand such issues are ordinarily identified by operational teams and encouraged a reinvigoration of supervision to improve performance.

CA established that clarity regarding asset management and development of future decommissioning strategy, is subject to completion of the DNB defueling safety case, anticipated in late 2022. Through discussion with the dutyholder, CA concluded that whilst the timeline for defueling is extensive, it would be advantageous to take an overlapping approach to decommissioning and deconstruction work. Removing redundant equipment alongside defueling, would enable a focus of resource on operating plant.  In addition, the peak of post defueling decommissioning work will be reduced. DNB confirmed a preference for this approach.

Conclusion of Intervention

A summary of inspection findings, verbal advice and additional document requests was shared with DNB at the close of the intervention.

An inspection rating of Green, no formal action has been assigned to this intervention.