Executive summary
Date(s) of inspection:
May 2025
Aim of inspection
The purpose of this readiness inspection is to judge if Sellafield Limited can demonstrate that the MSSS Original Building (OB) and First Extension (FE) silo liquor level system phase 2 modification can be implemented. The inspection plan is to sample evidence against several Licence Conditions to inform compliance against Licence Condition 22, modification or experiment on existing plant. The inspection will also follow up on any areas of focus identified in the specialist inspectors' assessment of the OB/FE LLM submission that Sellafield Limited needs to address prior to commencing active operations.
Subject(s) of inspection
- LC 22 - Modification or experiment on existing plant - Rating: GREEN
Key findings, inspector's opinions and reasons for judgement made
The readiness inspection focused on the hazards introduced by bringing the MSSS Original Building (OB) and First Extension (FE) liquor level management phase 2 modification into service and the measures by which Sellafield Ltd. ensures that the associated risks are reduced so far as is reasonably practicable. The inspection was undertaken against Licence Condition (LC) 22, modification or experiment on existing plant. The areas of focus was liquor containment, particularly the safety measures that control the risk associated with over-filling the compartments.
As part of the permissioning strategy development for MSSS OB/FE LLM Phase 1, I undertook an inspection on the MSSS facility of the inactive installation work.
Prior to the readiness inspection, Fault Studies, Chemical Engineering, Control and Instrumentation Engineering specialist inspectors and I obtained evidence from discussions with members of Sellafield Ltd.’s staff involved in the MSSS OB/FE LLM modifications. The inspectors subsequently assessed the adequacy of Sellafield Ltd.'s submission and key supporting documents. The findings from these engagements and assessments informed the readiness inspection scope. I utilised the following LCs to form my judgement on compliance with LC22.
- LC10: training.
- LC21: Commissioning
- LC23: operating rules.
- LC24: operating instructions
- LC28: examination, inspection, maintenance and testing.
Conclusion
On the basis of the evidence sampled, I judge that Sellafield Ltd. has provided evidence that the company's LC22 compliance arrangements are being adequately implemented for actively commissioning and bringing into service the MSSS OB /FE LLM system. Noting the ONR guidance on inspection ratings, it is my opinion that an inspection rating of green (no formal action) is appropriate.
I judged that the strategy to permission release of Hold Point 523 based on the evidence gained from inspection is still valid.