Office for Nuclear Regulation

Civil engineering inspection of Sellafield Special Nuclear Material (SNM) North (SNM(N)) facilities

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 inspection was for ONR to determine the adequacy of implementation of Sellafield Ltd.’s (SL’s) safety case claims on the civil engineering aspects for special nuclear materials north (SNM (N)) facilities. The inspection considered, on a sample basis, the condition of the civil aspects of the SNM(N) facilities, including: main SNM(N) buildings, Store 9, Store 9 Extension, filter housing building, pipe bridge structures and the “charcon” stack. The inspection scope excluded areas that are subject to major improvement projects; oversight for these projects is provided by an ONR Sellafield Project Inspector. The exception being for the civil asset improvement work for which reported progress was verified by visual inspection.

Interventions Carried Out by ONR

On the 11 - 12 July 2019, ONR carried out a planned 2-day inspection of the civil aspects of SNM(N) 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 this system, ONR examined evidence to verify the adequacy of the implementation of SL’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. Due to the nature of the system under consideration (i.e. passive outer building structure) LC27 and LC34 were not considered in detail and therefore not rated as part of this inspection.

ONR assessed compliance in SNM(N) against the following LCs by using the current  version of applicable ONR inspection guidance documents:

Explanation of Judgement if Safety System Not Judged to be Adequate

This safety system is judged to be adequate.

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

Overall, the inspection team considered the civil aspects of the building to be in reasonable condition with observable improvements in condition from previous inspections. Based on the sample inspected the ONR’s civil engineering inspector judged that the ONR Regulatory Issue action relating to civil refurbishment of the outer building condition had been satisfactorily completed.

SL were found to be effectively using their asset management database to understand and manage the health of the civil engineering structures. As part of this process SL had identified a number of technical issues associated with the civil engineering structures. However, from my inspection, I considered that there was appropriate evidence that these matters were being appropriately identified and acted upon. As SL recognise, it is important that SL continue to address the matters they have found in a timely manner.

Overall, I found LCs 10, 23, 24, and 28 (LC 27 and 34 were not formally rated due to the nature of the system under consideration) to be adequately implemented in relation to the system 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, and 28. No regulatory issues were raised during the inspection.   

Conclusion of Intervention

From the evidence sampled during the inspection, I judge that SNM(N) has adequately implemented the relevant claims in the safety case and that the formal arrangements for LCs 10, 23, 24, and 28  are being adequately implemented. Overall, I judge that the safety system is adequate and fulfils the requirements of the safety case.