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Dounreay - Inspection ID: 53691

Executive summary

Date(s) of inspection: 

  • March 2025

Aim of inspection

The aim of the inspection is to consider Nuclear Restoration Services (NRS) Dounreay Site's implemented measures to prevent, control and mitigate fire hazards affecting both nuclear safety and life safety. This includes reviewing Dounreay's examination of fires through their safety case documentation as well as building fire risk assessments and arrangements for compliance with the Fire Scotland Act and associated regulations.

Subject(s) of inspection

  • Fire (Life Safety) Compliance Inspection - Rating: AMBER
  • Fire (Scotland) Act 2005 - Rating: AMBER
  • LC10 - Training - Rating: GREEN
  • LC23 - Operating rules - Rating: AMBER
  • LC24 - Operating instructions - Rating: GREEN
  • LC27 - Safety mechanisms, devices and circuits - Rating: GREEN
  • LC28 - Examination, inspection, maintenance and testing - Rating: GREEN

Key findings, inspector's opinions and reasons for judgement made

This intervention was undertaken by an inspector from the Office for Nuclear Regulation’s (ONR) Nuclear Internal Hazards & Site Safety (NIHSS) specialism. An inspection covering Control of Major Accident Hazards (COMAH) compliance (IR-53692) was undertaken in parallel by another inspector from NIHSS and the Nominated Site Inspector (NSI). Where sessions were relevant to both inspections these were attended by multiple inspectors.

The inspection was carried out in line with relevant Technical Inspection Guides (TIG) such as NS-INSP-GD-073 Issue 2 – The Regulation of Life Fire Safety Provision on GB Nuclear Sites. The inspection consisted of examination of the licensee’s arrangements covering the above topics, meetings to assess the implementation and management of each topic at a site level and walkdowns of Fuel Cycle Area (FCA) buildings, the boiler house and associated fuel tanks and the Prototype Fast Reactor (PFR) Generator-Transformer House (GTR) and tank farm.

Several findings were noted during the inspection:

  • I reviewed examples of site fire risk assessments, fire system maintenance instructions and associated job cards as well as training evidence for key members of staff in fire safety roles. I found these to be broadly adequate.
  • I observed an area of good practice related to the implementation of fire and alarm and detection system asset information cards as a robust approach to obsolescence planning.
  • I observed some minor shortfalls related to fire safety management related to external staircases and the use of air horns within an occupied building. Dounreay have confirmed that the staircase in question has now been taken out of service and will be replaced as part of ongoing works. Dounreay also confirmed that the air horns were a temporary measure and the building fire alarm and detection system is fully operational.
  • The use of acetylene was noted within one of the fire risk assessments for an FCA building however, the current nuclear safety case documentation (Deterministic Fire Risk Assessment) did not assess the consequences of a fire or explosion involving acetylene. I further noted that acetylene is being used and stored in other areas of site however, the justification for use or consideration of suitable alternatives was not evident.
  • I noted that combustibles were stored directly below a Post Irradiation Examination (PIE) cell window. Further uncontrolled combustible laydown was noted within FCA buildings. It was not evident that operating instructions clearly articulated potential vulnerabilities to plant from local combustible accumulations. Additionally, the presence of potentially combustible insulation (polystyrene) within the walling system of an FCA building was noted. Currently the associated risk is not fully understood by the licensee.

[Note] - Following my inspection and post inspection discussions, Dounreay have pro-actively removed all Acetylene from site.

Conclusion

The following points which form my overall judgement are based on the facts established as part of the inspection, discussions with the nominated site inspectors and my own judgement on the presentations and information provided by the licensee:

  • The life fire safety condition of buildings is assessed through fire risk assessment and building condition surveys where required. Fire risk assessments for the buildings sampled were found to be broadly adequate.
  • Potential shortfalls related to fire safety management were observed on site however, site have proactively addressed or provided additional assurance related to these shortfalls.
  • Site are currently unable to ascertain the material state of some buildings in the context of potentially combustible insulation. Further work is required to confirm or refute the presence of polystyrene within some building envelopes. Should this be confirmed, assessment, justification or development of suitable and sufficient control measures may be required.
  • The control of combustibles within FCA buildings is not clearly linked to safety case requirements (operating instructions) with respect to areas of plant which may be vulnerable to localised fire hazards.
  • It is not clear that the risk associated with acetylene use on the site and potential consequences of a fire or explosion have been adequately considered. Controls in place do not cover all potential scenarios and a robust justification for the unavailability of suitable alternatives has not been provided.

I consider that the site is broadly complying with the license conditions inspected within the context of internal hazards. However, I judge that the nuclear fire safety case is not fully complete and this represents a shortfall against LC 23 with respect to the adequacy of the safety case LC23(1). I therefore judge that an ONR inspection rating of (GREEN) is appropriate for each license condition inspected with the exception of LC23 which I rate as (AMBER). I will consider this shortfall through ONR’s enforcement management model and establish an appropriate response to seek rectification.

I will raise a Level 4 Regulatory issue to address the shortfalls noted related to control of combustibles and the potential risks of combustible insulation. Other observations raised as part of this inspection will be taken forward with the dutyholder as part of normal regulatory business.

With respect to the life fire safety portion of the inspection I judge that the use of acetylene without supporting evidence to demonstrate no suitable alternatives is a shortfall against Regulation 11 of the Fire Safety (Scotland) Regulations 2006 and more generally, Regulation 4 of the Management of Health & Safety at Work Regulations 1999 “principles of prevention to be applied”. I will consider this aspect of the site’s use of acetylene as part of my enforcement judgement noted above. I consider that an ONR Inspection Rating of (AMBER) is therefore appropriate.

[Note] - Following my inspection and post inspection discussions, Dounreay have pro-actively removed all Acetylene from site.