- Site: Sellafield
- IR number: 21-018
- Date: May 2021
- LC numbers: 10, 23, 24, 27, 28, 34
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, a System Based Inspection (SBI) was carried out on the Magnox Reprocessing Facility (MRF) Pipebridges, as planned, on 11th-13th May 2021.
The purpose of this inspection was to enable ONR to form a view on the adequacy of the performance against the claims made within the safety case on the pipebridges under the control of the MRF and verify that the key equipment is available and maintained.
Interventions Carried Out by ONR
ONR’s SBI process examines evidence to determine compliance against six Licence Conditions (LC). These LC’s, listed below, have been selected in view of their relevance to ensuring nuclear safety and provide a structured approach to determining whether the safety case has been implemented adequately through the system being inspected.
LC 10 requires SL to make and implement adequate arrangements for suitable training for all those on site who have responsibility for any operations which may affect safety.
LC23 requires SL to produce an adequate safety case to demonstrate the safety of its operations, and to identify the conditions and limits necessary in the interests of safety.
LC24 requires SL to ensure that all operations which may affect safety are carried out in accordance with written instructions.
LC27 requires SL to ensure that a plant is not operated, inspected, maintained or tested unless suitable safety mechanisms, devices and circuits are properly connected and in good working order.
LC28 requires SL to make and implement adequate arrangements for the regular and systematic examination, inspection, maintenance and testing of all plant which may affect safety.
LC34 requires SL to ensure, so far as is reasonably practicable, that radioactive material and radioactive waste on the site is at all times adequately controlled or contained so that it cannot leak or otherwise escape from such control or containment.
Explanation of Judgement if Safety System Not Judged to be Adequate
Based upon the areas sampled I judge that the safety case requirements for the MRF pipebridges have been adequately implemented.
Key Findings, Inspector's Opinions and Reasons for Judgements Made
For LC 10 (Training), I targeted the training of an Operations Team Leader Duly Authorised Person (DAP), a Maintenance Team Leader, a Control Room Operator and a Maintenance Engineer associated with operational activities of the pipebridges and maintenance of the pre-selected Safety Mechanisms. Overall, I judged that the required standard was met and an inspection rating of Green (no formal action) is appropriate against LC10.
For LC 23 (Operating Rules) and LC24 (Operating Instructions) I was satisfied that the safety case clearly identified the fault sequences and that the 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 Licence Conditions 23 and 24.
For LC27 and LC28, I undertook a review of the maintenance records, pipebridge inspection reports and system health reports. During the inspection a minor shortfall was identified in relation to the justification for not completing the full inspection scope of one of the pipelines. This will be followed up as a Level 4 regulatory issue as part of routine regulatory business.
From the evidence sampled, I was satisfied that the relevant safety mechanisms were correctly identified in the safety case and operating instructions. I therefore judge that the required standard was met and an inspection rating of Green (no formal action) is appropriate against LC27.
Notwithstanding the shortfall identified in the pipeline inspection, overall, on the basis of the maintenance records sampled, the system health reports and inspections sampled, I was satisfied that the condition of the pipebridges was known and appropriate measures are in place to refurbish and repair any known problems. I therefore judge that the required standard is met and an inspection rating of Green (no formal action) is appropriate against LC28.
For LC 34, I reviewed the potential for leakage and escape of radioactive material in connection with MRF High Activity pipebridges and followed up on the progress of the remediation work from an incident that occurred on 10th September 2020 where there was a leak of Uranyl Nitrate (UN) from a pipebridge. I have raised a Level 4 regulatory issue to follow up on the chosen remediation option for the UN leak site as part of routine regulatory business. Notwithstanding the leak that occurred to the UN pipebridge, from the information sampled in the inspection, I was satisfied that the appropriate measures were in place to prevent and manage the leakage and escape of radioactive material in connection with the pipebridges. I therefore judge that the required standard is met and an inspection rating of Green (no formal action) is appropriate against LC 34.
Conclusion of Intervention
From the evidence sampled during the inspection, I judge that SL has adequately implemented the relevant claims in the safety case 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.