Radioactive Graphite Management at Uk Magnox Nuclear Power Stations

The UK nuclear power industry is predominantly based on gas-cooled, graphite moderated reactors with their being 20 operating and 6 shutdown Magnox reactors. The radioactive graphite issues associated with the Magnox reactors relate mainly to the reactor core graphite but, at two of the stations, there is also another graphite waste stream which results from the handling of their particular design of fuel elements which incorporate graphite fittings. The decommissioning plan for the Magnox reactors is to apply the Safestore strategy in which the defuelled reactors will be maintained in a quiescent state, e.g. to gain benefit from radioactive decay, with their dismantling being deferred for a period of time. In preparing for and developing the decommissioning strategy detailed studies have been undertaken on all relevant aspects. These have resulted in, for example, extensive information on the graphite radioactive inventories, the condition of the graphite throughout the quiescent deferral period, safety assessment, and, dismantling, waste management and disposal plans. Significant work has also been undertaken on the management of the graphite fuel element debris that has accumulated at the two stations. For example, work is well advanced at one of the stations to install equipment to retrieve this waste and package it in a form suitable for eventual deep geological disposal.