Office for Nuclear Regulation

Dounreay – Inspection ID: 52948

Date(s) of inspection

  • December 2023

Executive summary

Aim of inspection

In April 2023 ONR undertook an inspection of Dounreay’s alkali metal storage and management arrangements (IR-52418); this inspection identified that the risk of storing alkali metal across the Dounreay site does not meet recommended good practice. It was judged that alkali metal storage conditions in the Prototype Fast Reactor (PFR) turbine hall, steam generator hall and Generator Transformer House (GTH) are not adequate, as the licensee has failed to safely protect the drums against uncontrolled degradation via air and moisture ingress. It is also judged that the licensee is not recognising when there is degradation in these areas and then commencing appropriate remedial actions. An ONR enforcement letter was sent to Dounreay ONR-EL-23-005 in May 2023 on this matter and a holding to account meeting was held with Dounreay senior management in June 2023. This inspection was to follow up on Dounreay’s progress in addressing identified deficiencies.

Subject(s) of inspection

  • COSHH – Rating: Amber
  • Health & Safety at Work Act – Rating: Amber
  • LC4 – Restrictions on nuclear matter on the site – Rating: Amber
  • LC32 – Accumulation of radioactive waste – Rating: Amber

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

During the inspection Dounreay could not articulate any definitive commitments to any physical improvement in the bulk sodium storage arrangements. Dounreay had undertaken a review into the matter but no commitments were made with regard to addressing the issues raised or the recommendations. Further, Dounreay would not provide any further commitments for disposal of the bulk sodium stored in PFR turbine hall, generator transformer house or steam generator hall.

Repairs have been completed to the generator transformer roof to return the building to a weather proof state. Several ISO containers were inspected which showed areas where ISO containers have been corroded through, material was found that had leaked onto the floor and had not been identified by Dounreay staff, a number of storage drums in a corroded state which had been identified by Dounreay staff and were being monitored.

Despite being informed repairs had been completed to PFR turbine hall roof, the building was not weather tight and substantial amounts of water were leaking into the building which was accumulating in the areas around the sodium storage ISO containers. Further, Dounreay was storing unmarked chemicals within the turbine hall which we stated should be marked up, with the aim to dispose of the chemicals if no longer required. A number of cut electrical cables were identified during the inspection, the facility representative was confident these electrical cables were redundant however they did not have the correct marking or capping. These matters were left with the facility management but will be followed up as part of ONR separate interventions on electrical safety and chemical storage.

The sodium storage arrangements within PFR steam generator hall were unchanged from our last inspection, but we were informed that this area has been added to Dounreay’s sodium inspection regime.  During the inspection work was ongoing to clean and repaint the PFR steam generator hall structural steel work. Rain water was again coming into this building and the inspection team commented on the incorrect electrical cabling being used for the wet conditions.


Overall I judged that Dounreay’s bulk sodium storage arrangements remain inadequate. Further, no definitive arrangements have been established to improve the storage arrangement or dispose of this inventory. This matter will be further progressed through ONR’s enforcement management model.