- Site: Sellafield
- IR number: 21-42
- Date: June 2021
- LC numbers: 10, 23, 24, 27, 28, 34
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) safety case claims for the ventilation systems for Magnox East River (MER), Fuel Handling Plant (FHP). These ventilation systems support the containment safety functions.
Interventions Carried Out by ONR
On the 22nd to 24th June 2021, ONR carried out a planned three day inspection of the FHP ventilation system utilising specialists from the following technical disciplines:
- Mechanical Engineering
- Control and Instrumentation
In order to determine the adequacy of the licensee’s implementation of the safety case claims in respect of these systems, ONR examined evidence to verify the adequacy of the implementation of Sellafield Ltd’s arrangements for six pre-defined licence conditions (LCs), as listed below.
I inspected compliance in the MER FHP facilities against the following LCs by using the current versions of the applicable ONR inspection guidance documents:
- LC 10 – Training (NS-INSP-GD-010)
- LC 23 – Operating Rules (NS-INSP-GD-023)
- LC 24 – Operating Instructions (NS-INSP-GD-024)
- LC 27 – Safety Mechanisms, Devices and Circuits (NS-INSP-GD-027)
- LC 28 – Examination, Inspection, Maintenance and Testing (NS-INSP-GD-028)
- LC 34 – Leakage and Escape of Radioactive Material and Radioactive Waste (NS-INSP-GD-034)
The inspection involved reviewing the applicable claims in the safety cases and sampling evidence to determine compliance against the selected LCs on the plant. This was achieved through a combination of document reviews, plant inspections and discussions with operators and maintenance staff.
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 MER Ventilation system have been adequately implemented.
Key Findings, Inspector's Opinions and Reasons for Judgements Made
For LC 10 (Training), I targeted the training of an AGR Dismantler Duly Authorised Person (DAP), a Maintenance Team Leader and a Maintenance Engineer associated with operational activities of the Ventilation system 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 and system health reports. 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. Based on the maintenance records and the system health reports sampled, I was satisfied that the condition of the Ventilation 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 MER ventilation system. 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 Ventilation system. I therefore judge that the required standard is met and an inspection rating of Green (no formal action) is appropriate against LC 34.
During the inspection, no significant shortfalls where identified, however, there were some minor opportunities for improvement identified by the ONR inspection team and verbal advice was provided for each of these.
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.