- Site: Sellafield
- IR number: 21-091
- Date: September 2021
- LC numbers: 10, 23, 24, 27, 28, 34
Executive summary
Purpose of Intervention
The Office for Nuclear Regulation (ONR) undertakes all regulatory interaction with the Sellafield site licensee, Sellafield Limited, against a strategy defined by the ONR Sellafield, Decommissioning, Fuel and Waste Division. In accordance with that strategy, a System Based Inspection (SBI) was carried out on the Magnox Swarf Storage Silo (MSSS).
The purpose of this inspection was for ONR to examine whether the licensee’s safety case claims in respect of MSSS containment have been adequately implemented. The inspection comprised discussions with Sellafield Limited staff, a targeted plant walkdown and a review of plant records and other documentation.
ONR and the Environment Agency work collaboratively, where possible, due to the nature of the inspection and in the interests of efficient and effective regulation, this inspection was carried out with the support of Environment Agency.
Interventions Carried Out by ONR
ONR’s SBI process examines evidence to determine compliance against six licence conditions (LC). These LC’s, listed below, have been selected in view of their relevance to ensuring nuclear safety and provide a structured approach to determining whether the safety case has been implemented adequately through the system being inspected.
LC 10 requires Sellafield Limited to make and implement adequate arrangements for suitable training for all those on site who have responsibility for any operations which may affect safety.
LC23 requires Sellafield Limited to produce an adequate safety case to demonstrate the safety of its operations, and to identify the conditions and limits necessary in the interests of safety.
LC24 requires Sellafield Limited to ensure that all operations which may affect safety are carried out in accordance with written instructions.
LC27 requires Sellafield Limited to ensure that a plant is not operated, inspected, maintained or tested unless suitable safety mechanisms, devices and circuits are properly connected and in good working order.
LC28 requires Sellafield Limited 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 Sellafield Limited to ensure, so far as is reasonably practicable, that radioactive material and radioactive waste on the site is at all times adequately controlled or contained so that it cannot leak or otherwise escape from such control or containment.
The intervention was performed in line with ONR's guidance requirements (as described in our technical inspection guides) in the areas inspected.
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 MSSS containment system are able to fulfil their safety function requirements adequately, in line with the requirements of the MSSS safety case.
Key Findings, Inspector's Opinions and Reasons for Judgements Made
I identified minor shortfalls in relation to LC 27, LC 28 and LC 34. I raised these as an ONR Regulatory Issue at Level 4.
On the basis of the evidence sampled at the time of inspection, I judge that MSSS has adequately implemented those safety case claims that relate to the containment systems. I consider in respect of LCs 10, 23, 24, 27, 28 and 34 noting the ONR guidance on inspection ratings, that an inspection rating of Green (no formal action required) is merited here.
Conclusion of Intervention
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 identified some findings for which I have raised as an ONR regulatory issue at Level 4 to track SL’s progress of these matters.
Overall, I consider the safety case supporting this system to be adequately implemented.