Executive summary
Date(s) of inspection: July 2024
Aim of inspection
The purpose of the inspection was to judge the adequacy of Sellafield Ltd.’s readiness to commence operation of the Magnox Swarf Storage Silo (MSSS) nitrogen generation and storage plant (NG&SP) to support original building (OB) and first extension (FE) waste retrieval and FE pressurised inerting (PI). ONR has placed a regulatory hold point on this activity. ONR judged that for this proposal it was proportionate to utilise inspection to provide the main evidence to inform the permissioning recommendation. The inspection was undertaken against Licence Condition (LC) 22, modification or experiment on existing plant, utilising seven other unrated LCs to judge compliance.
Subject(s) of inspection
- LC22 - Modification or experiment on existing plant - Rating: GREEN
Key findings, inspector's opinions and reasons for judgement made
The inspection focused on the hazards that will be introduced by bringing the NG&SP into service on MSSS to supply nitrogen gas to OB and FE silo compartments (HP2j) and the measures by which Sellafield Ltd. ensures that the associated risks are reduced so far as is reasonably practicable.
ONR previously permissioned operation of the NG&SP to supply nitrogen gas to FE compartment C10 for retrieval and pressurised inerting (HP2a). As part of the retrievals programme’s phased approach, Sellafield Ltd. plans with HP2j to extend NG&SP nitrogen gas supply to OB and the remaining five FE compartments.
My inspection followed the same approach adopted for HP2a. An ONR chemical engineering specialist inspector provided me with some areas of focus for my inspection, all of which I consider have been adequately addressed. I obtained evidence from discussions with members of Sellafield Ltd.’s staff involved in HP2j and from sampling key documents. I utilised the following LCs to inform my judgement on compliance with LC 22.
- LC10: Training.
- LC21: Commissioning
- LC23: Operating rules.
- LC24: Operating instructions.
- LC26: Control and supervision of operations.
- LC27: Safety mechanisms, devices and circuits.
- LC28: Examination, inspection, maintenance and testing.
The inspection scope and sampling was informed by the evidence sampled during HP2a readiness inspection and HP2a permissioning. I did not identify any issue arising from the visit that needed me to consider further regulatory action.
Conclusion
On the basis of the evidence sampled, I judge that Sellafield Ltd. has provided evidence for adequately implementing LC22 compliance arrangements for HP2j. Noting the ONR guidance on inspection ratings, it is my opinion that an inspection rating of green (no formal action) is appropriate.
I consider that the strategy to permission release of HP2j based on the evidence gained from inspection is still valid.