- Site: Sellafield
- IR number: 21-167
- Date: February 2022
- 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 safety case claims for the fire protection systems at Magnox East River (MER), including Fuel Handling Plant (FHP), Site Ion Exchange Plant (SIXEP) and the AGR Waste Store.
Interventions Carried Out by ONR
On the 8th to 10th February 2022, ONR carried out a planned three-day inspection of the fire protection systems at MER utilising specialists from the following technical disciplines:
- Internal Hazards, including Nuclear Fire Safety; and
- Control and Instrumentation
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.
We inspected compliance in the MER 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 we judge that the safety case requirements for the MER fire protection systems have been adequately implemented.
Key Findings, Inspector's Opinions and Reasons for Judgements Made
For LC 10 (Training), we targeted the training of a Maintenance Team Leader and Maintenance Engineers associated with maintenance activities of the FHP fire detection and alarm system. Overall, we judged that the required standard was met and an inspection rating of Green (no formal action) is appropriate against LC 10.
For LC 23 (Operating Rules) and LC 24 (Operating Instructions) we were satisfied that the safety case clearly identified the fault sequences, limits and conditions associated with fire hazards and that there was adequate evidence of implementation in instructions to operators on plant, meeting the safety case requirements. We were content that the Operators and building management representatives questioned understood the relevant instructions and their nuclear safety significance. Based on the evidence sampled we judge that an inspection rating of Green (no formal action required) is merited against Licence Conditions 23 and 24.
For LC 27 we reviewed the visible condition of passive safety features during the plant walkdown and targeted the safety mechanisms, devices, and circuits with known shortfalls in the fire safety dashboard. We were satisfied that the relevant safety mechanisms identified in the safety case were clearly identifiable on plant, and that their condition was adequate or under adequate improvement programmes and managerial controls. We also sampled the implementation of recommendations raised in periodic safety reviews and found evidence on plant that they had been addressed with no shortfalls. We therefore judge that the required standard was met and an inspection rating of Green (no formal action) is appropriate against LC 27.
For LC 28, we targeted the maintenance of the safety mechanisms, devices and circuits and the system health reports in connection with the MER FHP and SIXEP fire protection and detection systems. We found some minor shortfalls in the retention of the completed work instructions and annual maintenance records. This shortfall is a known issue for MER and there exists an extant ONR Level 4 regulatory issue to address this and as such no further action is required to address this minor shortfall. We also found that the repairs of minor faults to the fire detection systems as identified in the licensee’s maintenance records could not be traced to completion. This minor shortfall will be followed up as Level 4 regulatory issue as part of routine regulatory business. Notwithstanding these minor shortfalls, based on the system health reports sampled and evidence of Systems, Structures & Components (SSC) functionality on plant we were satisfied that the functionality of the systems was not affected. We therefore judge that the required standard is met and an inspection rating of Green (no formal action) is appropriate against LC 28.
For LC 34 (leakage and escape), we targeted the potential for leakage and escape of radioactive material in connection with MER firefighting water routes and aerial/smoke releases. From the information sampled in the inspection, we were satisfied that the appropriate measures were understood and consistent with the licensee’s fire and rescue arrangements. We 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 were 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, we judge that Sellafield Ltd 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.