This intervention was undertaken on 21 – 22 January 2015 at Sellafield Limited’s (SL’s) Sellafield nuclear licensed site in Cumbria by an ONR Internal Hazards Specialist Inspector and an ONR Site Inspector.
Inspection of Licence Condition (LC) compliance at nuclear licensed sites forms a significant part of ONR’s activities. ONR’s Sellafield Programme has defined a programme of system inspections and LC compliance inspections to be undertaken on the Sellafield site; this is a key aspect of ONR’s regulatory strategy (for the Sellafield site). Undertaking this intervention is consistent with this strategy, and is identified on ONR’s PP4 inspection plan which covers Sellafield Limited’s Magnox Operating Unit.
The principal objective of this intervention was to identify any areas of concern that could preclude or delay the import of legacy fuels from the First Generation Magnox Storage Pond and the Pile Fuel Storage Pond into the Fuel Handling Plant (FHP) – a key element of the site’s risk and hazard reduction strategy..
The prime focus of this inspection was on lifting operations and the potential for dropped loads. I performed a plant walk-down, reviewed documentation and spoke to SL staff.
LC27 ‘Safety Mechanisms Devices and Circuits (SMDCs)’ requires the licensee to make and implement adequate arrangements to ensure that a plant is not operated, inspected, maintained or tested unless suitable and sufficient safety mechanisms, devices and circuits are properly connected and are in good working order.
LC28 ‘Examination, Inspection, Maintenance and Testing (EIMT)’ requires the licensee to make and implement adequate arrangements for the regular and systematic examination, inspection, maintenance and testing of all plant which may affect safety.
LC34 ‘Leakage and Escape Of Radioactive Material and Radioactive Waste’ requires the licensee to make and implement adequate arrangements to ensure that control and containment of radioactive materials and radioactive wastes on nuclear licensed sites is not lost due to their leakage or escape, and to ensure that any leakage or escape that does take place will be detected.
I completed compliance inspections against these three LCs in accordance with the following ONR guidance:
N/A. This was not a safety system inspection.
In assessing SL’s compliance against LC27, I sampled a number of key Safety Mechanisms (SMs) and Safety Related Equipment (SRE). All SMs were clearly labelled on the plant and were clearly designated as such in operating procedures and maintenance instructions. I judged an IIS rating of 3 (adequate) to be appropriate against LC27 because, with the exception of one SRE claimed for ‘A’ Line Monitoring, I found all SM and SRE to be properly connected and in good working order and consistent with ONR guidance requirements. The licensee had a justification in place for the non-availability of this SRE and it is expected to be available again in March 2015. I therefore, did not judge a lower IIS rating to be proportionate.
For LC28, I sampled the maintenance schedule, maintenance instructions and maintenance records for key SM and SRE. I judged an IIS rating of 2 (good standard) to be appropriate because I found the maintenance arrangements to generally exceed ONR’s guidance requirements for the sample, and I was content that the inspection regime in place was consistent with the requirements of the Lifting Operations and Equipment Regulations 1998 (LOLER). The licensee has proactively identified areas for improvement by means of System Health Reports for the Skip-handlers and the Inlet Cells / Ante-chambers which are being progressed satisfactorily.
For LC34, the use of road and rail-certified transport flasks (Magnox and AGR) and the robust nature of the handling operations related to these flasks informed my decision to sample a different operational activity. I therefore inspected the arrangements in place to detect the escape of radioactivity from spent fuel containers stored in the FHP pond.
It is not possible for the licensee to positively identify individual containers that are leaking because of the configuration of the pond and the storage arrangements within it. Maintaining an ‘ullage’ of nitrogen gas under the container lid is critical to preventing leakage. Further, maintaining pond water temperature within a specified range prolongs the lifetime of the ullage and minimises thermal expansion of the concrete pond structure. I therefore examined the pond water temperature recording and data-logging system and was content that the licensee was monitoring temperatures effectively and could take appropriate action to maintain these within the specified range. The licensee has also initiated a programme of work to improve the pond temperature and data logging system. I judge an IIS rating of 3 (adequate) to be appropriate against LC34 because the licensee’s arrangements meet ONR’s guidance requirements, and opportunities for improvement have been identified and are being actively pursued.
This was a very positive intervention which served to increase my understanding of the licensee’s case for future import of legacy fuels into FHP pond for interim storage. Based on the evidence gathered, no significant matters have been identified that are likely to impact on nuclear safety on the Sellafield site at this time.
Although no formal Regulatory Issues were raised in this intervention, there were two areas of note which are: i) the practicability of having container monitoring arrangements in place for individual containers prior to the import of legacy fuel into FHP and ii) the substantiation of any legacy skips that will be used for interim storage of fuel in FHP. These items will be managed and closed out by the Site Inspector with the support of the licensee’s internal regulator as part of normal regulatory business.