Executive summary
Date(s) of inspection:
- February 2023
Aim of inspection
The aim of this inspection was to determine whether the safety systems, structures and components associated with the ventilation system in the Magnox Swarf Storage Silo (MSSS) are able to adequately fulfil their safety duties (safety functional requirements), in line with claims made within the safety case.
Subject(s) of inspection
- LC 10 - Training - rating: Green
- LC 23 - Operating rules - rating: Green
- LC 24 - Operating instructions - rating: Green
- LC 27 - Safety mechanisms, devices and circuits - rating: Green
- LC 28 - Examination, inspection, maintenance and testing - rating: Green
- LC 34 - 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 MSSS ventilation system on the 21 and 22 February 2023. The inspection team comprised the Site Inspector for MSSS, Mechanical and Radiation Protection Specialist Inspectors and an Internal Hazards Inspector. The inspection included discussions with Sellafield Ltd. personnel, review of records, documents and processes and a targeted walk down of the facility.
MSSS arrangements and compliance against the following LCs were inspected as part of the SBI:
- LC 10 – Training; Given that the evidence confirmed that all sampled training had been completed and that the training was sufficient to allow effective operation of the ventilation system, it was considered that the arrangements for this licence condition have been implemented adequately resulting in a green inspection rating (No Formal Action).
- LC 23 – Operating Rules; The evidence sampled confirmed that the required Operating Instructions (rOIs) are available, clearly identify safety case requirements and are meaningful to operators resulting in a green inspection rating for this licence condition.
- LC 24 – Operating Instructions; It was judged that the operator instructions sampled included the instructions necessary to ensure that rOIs are implemented confirming that the arrangements for this licence condition have been implemented adequately, resulting in a green inspection rating.
- LC 27 – Safety Mechanisms, Devices and Circuits; From the sample of the licensee's arrangements and substantiating documentation, the Licence Condition was rated green as it was judged that that suitable and sufficient safety mechanisms, devices and circuits are properly connected and in good working order.
- LC 28 – 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 that the abatement system is meeting the decontamination factor claimed, is being appropriate assessed and is being monitored resulting in a green rating for this licence condition.
From the evidence sampled, I judged that Sellafield Ltd. had adequately implemented the safety case limits and conditions specified within the safety case. Furthermore, I was satisfied that the facility adequately understood the limits and conditions and their importance in the safety case. Evidence was seen that suitable and sufficient safety mechanisms, devices and circuits are properly connected and in good working order.
Conclusion
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 ventilation system within MSSS is judged to be adequate.