Office for Nuclear Regulation

Sellafield – Inspection ID: 50764

Executive summary

Date(s) of inspection:

  • May 2023

Aim of inspection

To determine whether the safety systems, structures and components associated with Legacy Ponds Civil Containment (including First Generation Magnox Storage Pond (FGMSP), Redundant Settling Tank (RST), Sludge Packaging Plant (SPP1) and Effluent Distribution Tank (EDT)) adequately fulfil their safety duties (safety functional requirements), in line with claims made within the safety case.

Subject(s) of inspection

  • LC10 – Training – Rating: Green
  • LC23 – Operating rules – Rating: Green
  • LC24 – Operating instructions – Rating: Green
  • LC27 – Safety mechanisms, devices and circuits – Rating: Green
  • LC28 – Examination, inspection, maintenance and testing – Rating: Green
  • LC34 – Leakage and escape of radioactive material and radioactive waste – Rating: Green

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

ONR carried out a planned two-day system based inspection (SBI) of the civil containment system in Legacy Ponds (including FGMSP, RST, EDT and SPP1 but  excluding PFSP on the 23 and 24 May 2023. The inspection team comprised the Site Inspector for Legacy Ponds, Civil and Fault Studies Inspectors as well as an international observing 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 as part of the SBI:
LC10 – Training; Given that the evidence confirmed that all sampled training had been completed and that the training was sufficient, it was considered that the arrangements for this licence condition have been implemented adequately resulting in a green inspection rating (No Formal Action).

LC23 and LC24 – Key safety case documentation is healthy, up to date and there is a clear golden thread between safety case and instructions.  These arrangements for these licence conditions have been implemented adequately resulting in a green inspection rating (No Formal Action).

LC27 – Safety Mechanisms, Devices and Circuits (SMDCs); Based on a review of maintenance records and observations during the plant walkdown, the SMDCs identified in the safety case were provided and were properly connected and in good working order.  Overall, on the basis of the sampled evidence, the arrangements for this licence condition have been implemented adequately, resulting in a green inspection rating.

LC28 – Examination, Inspection, Maintenance and Testing; Adequate examination, maintenance, inspection, and testing had been carried out in line with maintenance schedule requirements based  on the documentation examined, discussions and plant walkdown undertaken resulting in a green inspection rating for this licence condition.

LC34 – Leakage and Escape of Radioactive Materials and Radioactive Waste; Confidence was gained with Sellafield Ltd. systems for pond level monitoring, leak and crack detection and emergency response arrangements resulting in a green rating for this licence condition.


Overall, I found LCs 10, 23, 24, 27, 28 and 34  to be adequately implemented in relation to the systems inspected.

Consequently, it is my opinion that for this system-based inspection a rating of GREEN – No formal action is appropriate for LCs 10, 23, 24, 27, 28 and 34.  The civil containment systems within Legacy Ponds are judged to be adequate.