Office for Nuclear Regulation

Sellafield Site – Inspection ID: 52603

Executive summary

Date(s) of inspection:

June 2023

Aim of inspection

To gain confidence that Sellafield Ltd. is compliant with Licence Condition (LC) 23, 24 and 28 (specifically in relation to nuclear fire safety) and the Regulatory Reform (Fire Safety) Order 2005 within the Magnox Swarf Storage Silo (MSSS) facility at the Sellafield site to inform a regulatory judgement regarding the licensee’s compliance with its legal duties.

Subject(s) of inspection

  • Fire (Life Safety) Compliance Inspection – Rating: AMBER
  • LC 23 – Operating rules – Rating: GREEN
  • LC 24 – Operating instructions – Rating: GREEN
  • LC 28 – Examination, inspection, maintenance and testing – Rating: GREEN

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

ONR carried out a planned inspection of fire safety in Magnox Swarf Storage Silo (MSSS) on the 27 and 28 June 2023. The inspection team comprised the site inspector for MSSS, internal hazards specialist inspectors as well as a life fire safety specialist inspector. The inspection included discussions with Sellafield Ltd. personnel, review of records, documents and processes and a targeted walk down of the facility.

Arrangements and compliance against the following LCs were inspected :

LC 23 Operating Rules and LC 24 Operating Instructions – it was concluded that an inspection rating of GREEN was appropriate for these licence conditions. The retrievals safety case for nuclear fire safety has been adequately implemented in the operator instructions in use at the facility with several areas of good practice identified.

LC 28 Examination, Inspection, Maintenance and Testing – a rating of GREEN is also appropriate for this licence condition. ONR identified no specific concerns with the maintenance of nuclear fire safety features. Potential issues with the maintenance of fire dampers are identified under the RRO(FSO). No dampers are claimed for nuclear safety.

Compliance with the Regulatory Reform (Fire Safety Order 2005 (RRO) was also inspected. It was concluded that an inspection rating of AMBER was appropriate against the RRO. The current location of energised electrical cables in the protected staircases offers a significant challenge to the current travel distance assessment. In addition to this, the arrangements relating to the testing and maintenance of the fire dampers throughout MSSS does not offer the confidence that it is following relevant good practice.

The intervention was rated in line with the ONR General Inspection Guidance (ONR-INSP-GD-064). Consideration was given to progress against previous inspection findings in relation to the management and application of fire safety, and the application of the fire safety strategy.


Overall, I found LCs 23, 24 and 28 to be adequately implemented in relation to nuclear fire safety. Consequently, it is my opinion that for this inspection a rating of GREEN – No formal action is appropriate for LCs 23, 24 and 28.

However an inspection rating of AMBER – Seek improvement is appropriate against the Regulatory Reform (Fire Safety) Order. An enforcement decision record (ONR-EDR-23-018, 2023/36866) resulting in the decision to raise a level 3 regulatory issue (RI 11574) reflect the inspection outcome.