Office for Nuclear Regulation

Sellafield - System Based Inspection on Primary Separation

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) of the Plutonium Purification (PP) cycle and Plutonium (Pu) Evaporator and associated systems within the Magnox Reprocessing Facility (MRF), which is part of the Magnox Operating Unit (OU) was completed.  The purpose of this planned inspection was for ONR to confirm the adequacy of implementation of the licensee’s safety case claims in respect of this system.

As part of each SBI, ONR examines evidence of the adequate implementation of six pre-defined licence conditions.  These licence conditions (listed below) have been selected because of their importance to nuclear safety, and are defined within the ONR’s formal process for delivery of an SBI.

Interventions Carried Out by ONR

LC 10 requires SL to make and implement adequate arrangements for suitable training of those who have responsibility for any operations that may affect safety.

LC 23 requires SL to produce adequate safety cases to demonstrate the safety of its operations, and to identify the operating conditions and limits necessary in the interests of safety.

LC 24 requires SL to make and implement adequate arrangements for the provision of suitable written instructions for undertaking any operation that may affect safety.

LC 27 requires SL to ensure that, before a system is operated, inspected, maintained or tested, there are suitable and sufficient safety mechanisms, devices and circuits properly connected and in good working order.

LC 28 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.

LC 34 requires SL to ensure that its radioactive material and radioactive waste is at all times adequately controlled and contained, and that no leak or escape of that material or waste can take place without being detected.

The intervention focused on the operation and the maintenance of the safety of the PP Cycle and Pu Evaporator system within the MRF.  The inspection comprised discussions with SL staff, plant walk downs and reviews of plant records and documentation.

Explanation of Judgement if Safety System Not Judged to be Adequate

The Licensee has demonstrated that the Structures, Systems and Components (SSCs) which have been inspected as part of the MRF PP Cycle and Pu Evaporator systems are able to fulfil their safety function requirements adequately, in line with the safety case.

Key Findings, Inspector's Opinions and Reasons for Judgements Made

From the areas ONR targeted and the evidence ONR examined during this inspection, I consider that SL has adequately implemented those safety case claims that relate to the MRF PP Cycle and Pu Evaporator systems. I did identify several minor shortfalls in relation to LCs 10 and 24.These have been raised as three ONR Level 4 Regulatory Issues. On balance, I awarded inspection ratings of Green (No formal action) for LCs 23, 24, 27, 28 and 34.

I did however identify a significant shortfall against both relevant good practice and the implementation of Licensee arrangements in relation to LC10, specifically the local management of the Licensee arrangements for nominated electrical persons. I found these were not being appropriately controlled to ensure that the access to live electrical equipment cabinets is restricted to only those persons specifically nominated by the Licensee. This finding was accepted by the Licensee who committed to resolve this non-compliance with SLs arrangements immediately. On balance, I applied an inspection rating of Amber (Seek improvement) for LC 10 to reflect this. A shortfall has been raised as a Level 3 Regulatory Issue, which will be managed as part of normal regulatory business.

Conclusion of Intervention

No matters were identified as requiring immediate regulatory attention during the conduct of the system based inspection.

I have applied an inspection rating of Amber (Seek improvement) for LC 10.

I have applied an inspection rating of Green (No formal action) for LCs 23, 24, 27, 28 and 34.

Overall, on balance, I consider the safety case supporting this system to be adequately implemented.