Executive summary
Date(s) of inspection:
April 2026
Aim of inspection
The aim of this inspection was to determine the adequacy of Sellafield Ltd.’s readiness to safely commence the retrieval, overpacking and export of Special Nuclear Material (SNM) packages contained within the MOx Demonstration Facility (MDF) Lab L Magazine Store. This readiness inspection is part of the permissioning strategy (PR-01434) in response to Sellafield Ltd.'s request for ONR's agreement to this activity (releasing hold point 623) under Licence Condition (LC) 22.
Safely delivering the retrieval, overpacking and export activity is reliant on the adequate implementation of the safety case. The purpose of the readiness inspection was to gain assurance that Sellafield Ltd. has put in place the people, plant and procedures to safely implement the activity and inform ONR’s decision on whether to give agreement to permission the activity.
Subject(s) of inspection
- LC10 - Training - Rating: GREEN
- LC12 - Duly authorised and other suitably qualified and experienced persons - Rating: GREEN
- LC23 - Operating rules - Rating: GREEN
- LC24 - Operating instructions - Rating: GREEN
- LC28 - Examination, inspection, maintenance and testing - Rating: GREEN
Key findings, inspector's opinions and reasons for judgement made
I, the Project Inspector for SNM, supported by Human Factors Specialist Inspectors, undertook the intervention which comprised inspecting against five relevant licence conditions (LCs) (LC10 - Training, LC12 - Duly authorised and other suitably qualified and experienced persons, LC23 - Operating rules, LC24 - Operating instructions and LC28 - Examination, inspection, maintenance and testing). The inspection comprised of a plant walkdown, discussions with key personnel and the sampling of documentation related to this modification.
Included within the scope of this inspection was sampling of elements of the updated Dounreay Exotics Storage Facility (DESF) safety case where the Lab L packages will be exported to.
From the evidence sampled, I found that Sellafield Ltd was progressing towards an adequate state of readiness to commence the proposed activity.
The new limits and conditions being introduced by the proposed modification are recorded in a clear and unambiguous manner in relevant plant documentation. Engineered and operational safety measures are clearly identified in the safety case for the proposed activity and graded based on safety significance. These have been clearly and systematically incorporated into operational documentation, including operating instructions and inspection, maintenance and test instructions. Engineered safety systems were visually in an acceptable condition. New engineered safety measures introduced as part of the proposed modification have been subject to appropriate commissioning, verification and proof testing and suitable arrangements are in place for on-going examination, inspection, maintenance and testing.
Adequate arrangements are in place to ensure those undertaking and overseeing the activity are suitably qualified and experienced. Safety case awareness briefings have been delivered and a training package has been developed which is in the process of being delivered to the necessary staff. The formal training and assessments have yet to be completed, however I am satisfied that Sellafield has a plan, with appropriate management control, to deliver this ahead of commencing the proposed activity.
In my opinion, Sellafield Ltd Nuclear Independent Oversight (NIO) function had undertaken a comprehensive and objective Assurance Review. Sellafield Ltd provided assurance that there was a plan to close all significant findings.
Conclusion
I am of the opinion that Sellafield Ltd has adequately implemented the arrangements made under the nuclear site licence for the five LCs inspected during this intervention, and have awarded a rating of Green (no formal action) for each of these.
Based upon the evidence gained during this targeted inspection, in support of ONR's permissioning of the activity to commence active commissioning and operation of retrieval, overpacking and export of SNM packages contained within the MDF MDF Lab L Magazine Store; I judge that Sellafield Ltd has demonstrated it is progressing towards an adequate state of readiness to commence this activity. The inspection identified some areas that remain to be completed. However, I am satisfied that Sellafield Ltd. has a plan in place, with appropriate management control to close-out prior to commencement of the activity.
Sellafield Ltd has committed to closing out its own internal review actions, and the observations made by ONR during the inspection.
In my opinion the outcome of this readiness inspection supports ONR granting agreement to release of hold point 623 to allow retrieval, overpacking and export SNM packages contained within the MDF Lab L Magazine Store and export to DESF.