Executive summary
Date(s) of inspection: January 2024
Aim of inspection
To determine the adequacy of the dutyholder’s arrangements for operation of the station fuel route front end, including fuel build, against relevant licence conditions, and to ensure that the relevant parts of the station safety case are adequately implemented.
Subject(s) of inspection
- LC10 - Training - Rating: Green
- LC23 - Operating rules - Rating: Green
- LC24 - Operating instructions - Rating: Green
- LC27 - Safety mechanisms, devices and circuits - Rating: Green
- LC28 - Examination, inspection, maintenance and testing - Rating: Green
- LC34 - Leakage and escape of radioactive material and radioactive waste - Rating: Not rated
- Overall Inspection Rating - Rating: Green
Key findings, inspector's opinions and reasons for judgement made
The correct loading of nuclear fuel assemblies, assembled to the appropriate specification and to the right quality, is important to the safe operation of a reactor. The build of new fuel assemblies also utilises components that have already been irradiated within the reactor, and can therefore present a potentially significant source of dose uptake to the plant workforce. A team of ONR inspectors therefore conducted a systems-based inspection, focusing on the fuel route front end at Heysham 2 (HYB), using the guidance in ONR-INSP-GD-059 Issue 2. This in-person inspection focused on the new fuel import/storage route, the fuel decay store (in its function to store new unirradiated fuel assemblies prior to reactor deployment under offload depressurised refuelling (ODR)), and the fuel plug unit maintenance facility. The inspection was facilitated by desktop discussion and by visit to the relevant plant areas.
I found that the dutyholder’s representatives, drawn from the fuel route engineering and management teams, were able to explain how the station safety case had been implemented, and were also able to readily and competently answer questions related to the dutyholder’s arrangements. In addition, the dutyholder operations and maintenance personnel seen on plant demonstrated an adequate understanding of the arrangements under which they work.
I could link the protection systems designated within the safety case through to their implementation on plant. I also saw evidence that the limits and conditions identified within the safety case requirements were specified in operating instructions, which I observed being followed on plant. I therefore rate LC23 and LC24 as both GREEN (No Formal Action).
I found evidence that safety interlock systems on plant were visibly well maintained, and subsequently saw the records that demonstrated that they had been maintained in accordance with their specified maintenance period, and that the personnel associated with their operation and maintenance understood the functioning of the interlocks and could adequately describe their functional testing. Furthermore, I observed the preparation for maintenance and overhaul of an ex-reactor fuel plug units at the fuel plug unit maintenance facility using written instructions which were correctly followed. I therefore rate LC27 and LC28 as both GREEN (No Formal Action).
I also sampled the system used by the dutyholder to track training for individual role holders, and found evidence that the training which individuals need for the role that they perform is adequately specified and recorded. I carried out a cross check of the new fuel build certification signature sheet, and found that the signatories were correctly trained for the role that they were performing. I therefore rate LC10 as GREEN (No Formal Action).
I also examined the records related to the build history for a fuel assembly for a chosen channel in one of the reactor units. I found evidence that the assembly had been built to the correct specification, and that the interfaces between the personnel responsible for its deployment, including the reactor physicist, control room personnel, and fuel assembly engineering team, were adequate.
I have not rated against LC34 because the systems inspected did not cover arrangements against LC34.
Conclusion
This inspection focused on the front end of the fuel route from fuel receipt to loading into the reactor, and the inspection outcome was facilitated by the preparedness and openness of the dutyholder’s representatives. Based on my sample, I have made my regulatory judgement against each of the Licence Conditions covered in relevant ONR guidance, with the exception of LC34, which I leave unrated as it was out of the scope of the inspection. The rating for the other aspects is GREEN, and my overall judgement for this inspection is GREEN (No Formal Action).