Executive summary
Date(s) of inspection: November 2024
Aim of inspection
The purpose of this inspection was to enable ONR to form a view on the claims made within the safety cases associated with the Line 3 containment systems under the control of the High Level Waste Plants (HLWP) and verify that the key equipment is available and adequately maintained.
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
- Overall Inspection Rating - Rating: Green
Key findings, inspector's opinions and reasons for judgement made
This Intervention Record (IR) captures key regulatory observations made during a planned system based inspection (SBI) of the High Level Waste Plant (HLWP) Waste Vitrification Plant Line 3 containment systems. ONR’s System Based Inspection process examines evidence to determine compliance against six key licence conditions (LCs) 10, 23, 24, 27, 28 and 34.
For Licence Condition 10, I targeted the training of two Maintainers who carried out maintenance on the cell sump detection systems, the associated ASQEP Maintenance Team Leader and two Line 3 Operators who would be involved in the monitoring and response to a loss of containment incident. Overall, I judged that the required standard was met and an inspection rating of Green (no formal action) is appropriate against LC10.
For Licence Condition 23 and 24, I targeted the relevant Operating Rules (ORs), Referenced Operating Instructions (ROI), Operating Instructions (OI) and Emergency Instructions (EI) in connection with HLWP Line 3 containment systems. Overall, I was satisfied that the safety case clearly identifies the fault sequences and that the operation and emergency instructions followed a detailed step wise format and contained the relevant steps to meet the safety case requirements. Based on the evidence sampled I judge that an inspection rating of Green (no formal action required) is merited against License Conditions 23 and 24.
For LC27, I targeted the relevant safety mechanisms in connection with the leak detection of radioactive liquor from Line 3 primary containment. For LC28, I targeted the maintenance of the preselected safety mechanisms, the Inspection regimes (CCTV) and the System Health Reports (SHR) in connection with the HLWP Line 3 containment systems. Overall, on the basis of the maintenance records sampled, the system health reports, CCTV inspections sampled and plant walk round, I was satisfied that the HLWP arrangements for maintenance and asset management of the Line 3 containment systems are adequate and was satisfied that the condition of the containment systems were known and maintained to an appropriate standard. Based on the evidence sampled, I judge that the required standard is met and an inspection rating of Green (no formal action) is appropriate against Licence Condition 27 and 28.
For LC 34, I reviewed the potential for leakage and escape of radioactive material in connection with HLWP Line 3 containment systems. Overall, I was satisfied that the appropriate measures were in place and judge that the required standard is met and an inspection rating of Green (no formal action) is appropriate against LC 34.
From the areas sampled, I provided some regulatory advice and observations but did not identify any shortfalls in the implementation of the licensee’s arrangements which would necessitate a further inspection of the Line 3 containment systems earlier than currently planned.
Based upon the areas sampled I judge that the safety functions associated with the Line 3 containment systems (which support the relevant claims in the safety case) under the control of the HLWP have been adequately implemented.
Conclusion
From the evidence sampled during the inspection, I judge that HLWP has adequately implemented the safety function of the Line 3 containment systems and that the formal arrangements for LCs 10, 23, 24, 27, 28 and 34 are being adequately implemented. For LCs 10, 23, 24, 27, 28 and 34 an inspection rating of Green (no formal action) is merited.