- Site: Sellafield
- IR number: 22-027
- Date: June 2022
- LC numbers: 10, 23, 24, 27, 28, 34
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 Limited’s (SL’s) safety case claims for the Sellafield Product and Residues Store (SPRS). The scope focused on the ventilation of the store. Effective cooling of the store relates to the fundamental safety functions of cooling, containment and indirectly control (criticality). The safety function of the product packages contained within the store was excluded.
On 8 and 9 June 2022, I carried out a planned two-day inspection of the SPRS supported by three specialists, the inspection team encompassed the following technical disciplines:
- Fault Studies
- Mechanical Engineering
- Operational Inspection
In order to determine the adequacy of the licensee’s implementation of the safety case claims in respect of these systems, I examined evidence to verify the adequacy of the implementation of Sellafield Limited’s arrangements for six pre-defined licence conditions (LCs), as listed below. These LCs have been selected in view of their importance to nuclear safety and are defined within ONR’s formal process for SBIs.
The inspection involved reviewing the applicable claims in the safety cases and then sampling suitable 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.
I inspected compliance in the SPRS against the following LCs by using the current versions of the applicable ONR inspection guidance documents:
- LC10 – Training (NS-TAST-GD-027)
- LC23 – Operating Rules (NS-INSP-GD-023)
- LC24 – Operating Instructions (NS-INSP-GD-024)
- LC27 – Safety Mechanisms, Devices and Circuits (NS-INSP-GD-027)
- LC28 – Examination, Inspection, Maintenance and Testing (NS-INSP-GD-028)
- LC34 – Leakage and Escape of Radioactive Material and Radioactive Waste (NS-INSP-GD-034)
Key Findings, Inspector’s Opinions and Reasons for Judgements Made
Evidence was seen that Sellafield Limited is subjecting the store ventilation to an adequate level of Examination, Inspection, Maintenance and Testing (EIMT), which is undertaken, controlled and supervised by suitably trained personnel. The evidence included EIMT records, training records, system health reports and a physical walk down of accessible areas of the plant.
From the evidence sampled, I judged that Sellafield Limited had adequately implemented the safety case limits and conditions specified within the safety case. The evidence included sampling of the audit trail from the safety case clearance certificates through to the operating and EIMT Instructions; completed operating rounds and surveillance sheets, the control room log, and the annual thermal performance review. From a combination of inspecting the EIMT records, photographs, and the plant walk down, evidence was seen that suitable and sufficient safety mechanisms, devices and circuits are properly connected and in good working order. A Level 4 Regulatory Issue was raised in order to oversee improvements to be made to the labelling of systems, structures and components with a nuclear safety role.
Evidence was seen that suitably trained Duly Authorised Persons (DAPs) had been appointed for the control and supervision of the operations. I saw sufficient evidence to be able to judge that the plant operators were suitably trained.
Some minor opportunities for improvement were identified during the inspection that resulted in regulatory advice, and Sellafield Limited raising some condition reports in line with its internal processes. Overall, I found that LCs 10, 23, 24, 27, 28 and 34 to be adequately implemented in relation to the systems inspected. Consequently, it is my opinion for this system based inspection that a rating of GREEN – No formal action is appropriate for LCs 10, 23, 24, 27, 28 and 34.
Conclusion of Intervention
From the evidence sampled during the inspection, I judge that Sellafield Limited 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. Overall, I judge that the safety system adequately fulfils the requirements of the safety case.