This intervention, conducted at the Licensee’s Sellafield Limited (SL) Cumbria licensed site, was undertaken as part of the 2018/19 intervention plan and the Sellafield sub-division strategy.
ONR conducted a System Based Inspection (SBI) of the First Generation Magnox Storage Pond (FGMSP) Ventilation System. The scope of this inspection considered the operation, maintenance and structural integrity of the ventilation system to abate radioactive discharges and maintain nuclear safety. The delivery of this function is important to safety for FGMSP, and for high hazard and risk reduction operations more generally.
ONR’s SBI process examines evidence to determine compliance against six key licence conditions (LCs). These licence conditions (listed below) have been selected in view of their relevance to ensuring nuclear safety and in providing a structured approach to determining whether the safety case has been implemented adequately through the system being inspected.
LC10 requires SL to make and implement adequate arrangements for suitable training of those who have responsibility for any operations that may affect safety.
LC23 requires SL to produce an adequate safety cases to demonstrate the safety of its operations, and to identify and implement operating conditions and limits necessary in the interests of safety.
LC24 requires SL to make and implement adequate arrangements for the provision of suitable written instructions for undertaking any operation that may affect safety.
LC27 requires SL to ensure that, before a system is operated, inspected, maintained or tested, all 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 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.
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 First Generation Magnox Storage Pond (FGMSP) Ventilation System are able to fulfil their safety functional requirements adequately, in line with the safety case.
During the course of the inspection I identified a conventional health and safety matter associated with crane operations which required immediate licensee attention. I was satisfied with the manner in which the licensee responded to this risk, and I therefore will take no further action here.
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 FGMSP Ventilation System. In particular, SL has undertaken a significant amount of work to maintain and improve the ventilation function within the FGMSP facility with suitably qualified and experienced personnel. I also identified several minor improvements that could be made. On balance, I awarded inspection ratings of Green (No formal action) for LCs 10, 23, 27, 28 and 34.
I identified one specific area for improvement. Although SL has in place a detailed planned maintenance regime, ONR identified a significant shortfall in that the sampled procedures had the potential to cause errors in their use, and they failed to provide an adequate means of recording compliance. I also identified several minor improvements that could be made. Overall, there was good evidence of improvements and maintenance works for the ventilation system but the sample review of procedures for the operation and maintenance of the ventilation system showed the documentation as having errors and omissions which affected clarity of purpose, responsibilities and clear links to the extant safety case. I judge that this is a significant shortfall in the implementation of SL’s arrangements. Therefore on balance, I awarded an inspection rating of AMBER (Seek improvement) for LC 24 due to these shortfalls.
I consider that the licensee has a good knowledge of the physical condition of the Structures, Systems and Components reviewed during this inspection and has in place appropriate management controls to ensure on-going safety.
I have, however, identified one specific area for improvement, which requires appropriate attention from the licensee. I have therefore raised an ONR Regulatory Issue at Level 3.
I have also identified several minor improvements that could be made for improving the FGMSP ventilation system. I have therefore raised a number of ONR Regulatory Issues at Level 4 to track SL’s progress of these matters.
Overall, on balance, I consider the safety case supporting this system to be adequately implemented.