Office for Nuclear Regulation

Sellafield - System Based Inspection of First Generation Magnox Storage Pond sludge retrievals

Executive summary

Purpose of Intervention

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) of First Generation Magnox Storage Pond (FGMSP) sludge retrievals system to confirm the adequacy of implementation of the safety case.  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 15 – 17 July 2019, ONR carried out a planned 3-day inspection of the First Generation Magnox Storage Pond utilising specialists from the following technical disciplines:

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 SL’s arrangements for six pre-defined licence conditions (LCs), as listed below. These LCs have been selected in view of their importance to nuclear safety and are defined within ONR’s formal process for SBIs.

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.

ONR assessed compliance against the following LCs by using the applicable ONR inspection guidance documents:

Explanation of Judgement if Safety System Not Judged to be Adequate

The safety system is judged to be adequate.

Key Findings, Inspector's Opinions and Reasons for Judgements Made

Whilst some minor opportunities for improvements were identified, 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.

Conclusion of Intervention

From the evidence sampled during the inspection, I judge that Sellafield Limited has adequately implemented its safety case and that the formal arrangements for LCs 10, 23, 24, 27, 28 and 34 are being adequately implemented.

The ONR inspectors identified a number of minor shortfalls and provided advice, which was accepted by SL.  SL’s Nuclear Independent Oversight section will maintain oversight.  I therefore consider it is not necessary to raise a regulatory issue.

Overall, I judge that the safety system is adequate and fulfils the requirements of the safety case.