Office for Nuclear Regulation

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Compliance inspections at Sellafield

Executive summary

Purpose of Intervention

The Office for Nuclear Regulation (ONR) undertakes all regulatory interaction with the Sellafield site licensee (Sellafield Limited, SL) against a strategy defined by the ONR Sellafield Sub Division. In accordance with that strategy, Licence Condition (LC) compliance inspections were carried out on the Operational Waste Facilities Operating Unit (OU), as planned, in October 2017.

Interventions Carried Out by ONR

On 10 and 11 October 2017, I carried out a two-day, on-site licence condition compliance inspection of the Waste Encapsulation Plant (WEP) within the operational waste facilities OU. The purpose of this inspection was for the ONR to determine the adequacy of implementation of the licensee's formal arrangements for compliance with LC 27 (safety mechanisms, devices and circuits), LC28 (examination, inspection, maintenance and testing) and LC34 (leakage and escape of radioactive material and radioactive waste). The inspection comprised of discussions with SL staff, a targeted plant walk down, observation of and interviews with operational staff, and reviews of plant records and other documentation.

In addition follow up enquiries were conducted in the Miscellaneous Beta Gamma Waste Store (MBGWS) and the Highly Active Liquor Evaporation and Storage (HALES) facility following recently reported events in these facilities (INF1s 2017/642 and 2017/650 respectively).

Explanation of Judgement if Safety System Not Judged to be Adequate

This was not a system based inspection, and therefore no judgement has been made of the adequacy of implementation of any part of the safety case.

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

Prior to the LC27, LC28 and LC34 inspection, I undertook a review of the relevant Sellafield procedures against the relevant ONR guidance document for these licence conditions; NS-INSP-GD-027 Revision 3, NS-INSP-GD-028 Revision 5 and NS-INSP-GD-034 Revision 3 respectively. From those areas sampled, I did not identify any significant shortfalls in the licensee's formal arrangements for compliance which would prompt an inspection of those arrangements earlier than currently planned.

In order to judge the adequacy of the implementation of these arrangements within the facility, I targeted some of the key Gamma interlocks designated as safety mechanisms and the following aspects of the slurry receipt cell sumps systems; SF15, floor cladding and SM75, slurry receipt cell sump ejection system including their maintenance requirements.

From the areas sampled I identified a clear route from the safety case to the designation of the gamma interlocks and associated maintenance. In particular I followed up on the recent improvements made on proof testing following a shortfall reported under INF1 2017/406 and recorded under ONR issue 5248. I was satisfied that the required safety improvements had been made. I also sampled the associated maintenance records and, although I made some regulatory observations on how these could be improved, I considered that these met the required standard. On this basis I judged that compliance with LC27, LC28 and LC34 followed the relevant company procedures and met the required standard and therefore I have rated this intervention against these licence conditions as Green.

As part of my follow up enquires relating to INF1s 2017/642 and 2017/650, I spoke to the relevant operations managers, system engineers and visited the plant. I also reviewed the associated paperwork and in both cases judged that these events do not meet the ONR formal investigation criteria. Any trends will be monitored as part of normal regulatory business.

The intervention was performed in line with ONR’s guidance requirements (as described in our technical inspection guides) in the areas inspected.

Conclusion of Intervention

From the evidence gathered during this intervention, I do not consider there to be any matters that have the potential to impact significantly on nuclear safety.

At present, no additional regulatory action is needed over and above the planned interventions within the Operational Waste Facilities Operating Unit at the Sellafield Nuclear Site as set out in the Integrated Intervention Strategy, which will continue as planned.