Hartlepool/Heysham 1 fuel route consolidation and development

The fuel routes at each advanced gas-cooled reactor power station are required to operate safely and reliably to keep the reactors operational. On average, about one-sixth of the total fuel inventory must be renewed each year. A variety of refuelling modes are employed at particular stations arising from detailed design, historical and safety case considerations. At Hartlepool and Heysham 1, which are of the same design, routine refuelling is done in batches with the reactors off-load and depressurized (although pressurized off-load refuelling is also permitted). The batches are as large as practicable in order to minimize output losses due to refuelling. The batch process involves both (a) the exchange of spent fuel assemblies for new ones (b) the transfer of part-burnt fuel assemblies to new positions in the core to improve fuel utilization-known as 'radial shuffling'. Once the batch is complete, a programme of irradiated fuel disposals (separating the fuel assemblies into individual fuel elements and culminating in the dispatch of fuel elements off site in flasks) and new fuel assembly builds is begun. These operations involve the use of several fuel route plant facilities including cooling ponds. The refuelling process from the build of new fuel to the final handling of complete irradiated fuel assemblies is covered by a refuelling safety case. Further safety cases exist for the handling of individual irradiated elements both on and off site. All these cases are updated as necessary via a formal plant modifications procedure and they have recently been subject to a ten-yearly periodic safety review (PSR). Arising from the PSR, work to consolidate the cases is in progress including studies in the seismic and human factors areas. Development work to improve the efficiency of the fuel route is also under way. This involves process improvements to assist operators engineered improvements to improve speed and reliability fuel utilization improvements by increases in discharge irradiation and radial shuffling. A vision of fuel route operation is presented which minimizes the required plant availability and hence increases the flexibility of operation. In order to achieve this vision an increase in reliability of the fuel route equipment will be needed and an increased utilization of the available storage capacity in the cooling ponds. (author)