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Sellafield - Inspection ID: 52975

Executive summary

Date(s) of inspection: November 2024

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

In accordance with the Office for Nuclear Regulation’s (ONR’s) Sellafield Strategy, each year ONR performs a series of planned system based inspections (SBIs) targeted on key safety significant systems.  The purpose of this particular intervention was to undertake a System Based Inspection (SBI) on First Generation Magnox Storage Pond (FGMSP) sludge retrievals system to confirm the adequacy of implementation of the safety case. As the system transfers sludge to the Sludge Packing Plant 1 (SPP1) and the Effluent Distribution Tank (EDT) these buildings were included in the scope of the intervention.

ONR sampled evidence to support the claims made in the safety case and to ascertain compliance against Licence Conditions 10, 23, 24, 27, 28 and 34. The inspection sampled the FGMSP sludge retrievals equipment and associated safety measures.

Interventions Carried Out by ONR

Between 27-28 November 2024, ONR carried out a planned 2-day inspection of the First Generation Magnox Storage Pond utilising specialists from the following technical disciplines:

  • Control & Instrumentation
  • Electrical Engineering
  • Fault Analysis
  • Operational Inspection

In order to determine the adequacy of the licensee’s implementation of the safety case claims in respect of these systems, ONR examined evidence to verify the adequacy of the implementation of Sellafield’s arrangements for six pre-defined licence conditions (LCs). These LCs have been selected in view of their importance to nuclear safety and are defined within ONR’s formal process for SBIs. ONR assessed compliance against by using the applicable ONR inspection guidance documents:

  • LC 10 – Training (NS- INSP-GD-010)
  • LC 23 – Operating Rules (NS-INSP-GD-023)
  • LC 24 – Operating Instructions (NS-INSP-GD-024)
  • LC 27 – Safety Mechanisms, Devices and Circuits (NS-INSP-GD-027)
  • LC 28 – Examination, Inspection, Maintenance and Testing (NS-INSP-GD-028)
  • LC 34 – Leakage and Escape of Radioactive Material and Radioactive Waste (NS-INSP-GD-034)

The inspection involved reviewing the applicable claims in the safety cases and then sampling suitable evidence to determine compliance against the selected LCs on the plant. This was achieved through a combination of document reviews, plant inspections and discussions with operators and maintenance staff.

The safety system is judged to be adequate.

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.

Some minor opportunities for improvements were identified and shared with Sellafield as “advice and guidance”.
I have recommended that one Level 4 Regulatory Issue is raised in relation to the EDT overfill protection system.

Conclusion

Licence Condition 10 (Training)

Judgement: Overall, we were satisfied that the training arrangements for operators and maintainers had been adequately implemented. As such, we judged an inspection rating of GREEN – no formal action.

Licence Condition 23 (Operating Rules) and Licence Condition 24 (Operating Instructions)
Judgement: Overall, we were satisfied that the limits and conditions identified within the safety case are being adequately implemented within the facility. As such, we judged an inspection rating of GREEN – no formal action, for both LC.

Licence Condition 27 (Safety Mechanisms, Devices and Circuits) and Licence Condition 28 (Examination, Inspection, Maintenance and Testing)

Judgement: Overall, based on the sampling undertaken we were satisfied with implementation of arrangements for the SMs and associated EIMT. As such, we judged an inspection rating of GREEN – no formal action, for both LC.

We identified a shortfall on to the proof test for the pond purge system which is linked to the EDT overfill protection system as it did not appear to cover all potential failure modes. I recommend that a Level 4 Regulatory Issue is raised seeking clarity on whether all of the failure modes should be covered by the test, or justification as to why the extant proof test is suitable.

Licence Condition 34 (Leakage and Escape of Radioactive Material and Radioactive Waste)

Judgement: Overall, we were satisfied that the arrangements for the leakage of radioactive material in the safety case are being adequately implemented within the facility. As such, we judged an inspection rating of GREEN – no formal action.