Executive summary
Date(s) of inspection: January 2025
Aim of inspection
The inspection aimed to evaluate the safety and operational robustness of the Separation Area Ventilation System by reviewing its safety claims, configuration management, maintenance planning, and operational oversight. Key areas included compliance with Licence Condition (LC) 11 (Emergency Arrangements), LC24 (Operating Instructions), and LC26 (Control and Supervision of Operations). Additionally, the inspection will assessed the system’s role in the ventilation cascade and ensure appropriate responses to unforeseen events or faults during maintenance LC28(6).
The inspection was reactive in response to INF-4531 which involved a series of unexpected failures during planned fuse board maintenance.
Subject(s) of inspection
- LC11 - Emergency arrangements - Rating: Not rated
- LC24 - Operating instructions - Rating: Not rated
- LC26 - Control and supervision of operations - Rating: Not rated
- LC28 - Examination, inspection, maintenance and testing - Rating: Not rated
Key findings, inspector's opinions and reasons for judgement made
This reactive inspection was conducted in response to INF-4531, following a series of unexpected failures within the Separation Area Ventilation System during planned fuse board maintenance. There were no radiological consequences from the event and the plant was promptly returned to normal operational status and configuration.
The inspection focussed on unresolved regulatory concerns related to system behaviour, configuration, risks from system failures, indication and staffing response capabilities. However, insufficient evidence was provided to justify or address these concerns. As a result, the concerns remain. Additionally, I have identified shortfalls in how ergonomics have been considered in minimum manning claims, as well as potential gaps in compliance with other regulatory requirements. Given these ongoing concerns, it is considered proportionate to issue a letter outlining the regulatory issues and associated advice, ensuring that Sellafield Limited understands the problem and implements appropriate corrective actions.
Conclusion
During my inspection planning, I previously outlined a list of outstanding regulatory concerns and focus areas in regulatory advice letter SEL-77861-N. However, I have not received sufficient evidence to justify or address these concerns. As a result, I remain uncertain about the systems behaviour, configuration, and the associated risks from system failures. I also continue to have broader concerns regarding staffing levels, as well as the system's indication and response capabilities.
My primary focus is on the risks associated with system failures. Specifically, the need for Sellafield Limited to understand the consequences for adjoining facilities, the potential impact to workers and operations in terms of dose and spread of contamination, and the required response timescales for any faults. To establish realistic response times, Sellafield Limited should conduct an analysis of potential faults and failure modes associated with the system's hardwired logic.
A second key concern relates to the general staffing situation within civil services. This issue is closely linked to my first concern, as the time required to respond to SAV system faults will directly impact staffing levels. Additionally, I have identified shortfalls in how ergonomics have been considered in minimum manning claims, as well as potential gaps in compliance with other regulatory requirements, such as those set by the Environment Agency.
At this stage, I do not have sufficient evidence to pursue formal enforcement action relating to the radiological risks from the ventilation system, as the risk associated with these gaps remain unquantified. Instead, I have concluded that it would be proportionate to send a letter outlining these concerns and providing regulatory advice to help Sellafield Limited understand the problems and implement corrective actions. I have noted other observations separately, including failures to learn from past events and a concerning level of staff and organisational tolerance toward working with a degraded system. These issues raise cultural concerns that warrant further attention.