Carbowaste - Closing the Fuel and Graphite Cycles for HTR

The European Project on "Treatment and Disposal of Irradiated Graphite and other Carbonaceous Waste (CARBOWASTE)" has been launched in 2008 under the 7th EURATOM Framework Programme (FP7-211333), with duration of four years. This project addresses the retrieval, treatment and disposal of irradiated graphite (i-graphite) including other carbonaceous waste like structural material made of graphite or non-graphitized carbon bricks and fuel coatings (pyrocarbon, silicon carbide). It addresses both existing legacy waste as well as waste from graphite-based nuclear fuel resulting from a new generation of nuclear reactors (e.g. V/HTR, Fusion). The CARBOWASTE project is of major importance for the deployment of HTR as each HTR module generates about 5,000 to 10,000 Mg of contaminated i-graphite containing some Peta-Becquerel of radiocarbon, during a 60 years operational lifetime. Most of this i-graphite is associated with the moderator, which is an integral part of the HTR fuel element. Significant progress has been achieved with regards to the techniques for separating the coated particles from the moderator graphite of High-Temperature Reactor (HTR) fuel. Pulsed power fragmentation facilities for HTR fuel compacts and HTR pebble fuel have been put into operation and tested with unirradiated dummy fuel. Further separation methods like homogeneous oxidation, use of intercalation compounds, laser techniques, electrochemical deconsolidation, molten-salt methods etc. have also been investigated. Although tests with irradiated fuel are still pending, it can already be stated that head-end facilities for the reprocessing of spent HTR fuel appear to be feasible and that the HTR fuel cycle can be closed. It has been discovered that a significant part of the contamination (including 14C) can be removed from irradiated graphite by thermal, chemical or even microbiological treatment. The feasibility of the associated processes is experimentally investigated to determine and optimize the decontamination factors. Reuse of the purified material will also be addressed to close the ¿Graphite Cycle¿ for future graphite moderated reactors. The disposal behavior of graphite and carbonaceous wastes and the improvement of suitable waste packages are another focus of the programme. It is strongly recommended to take decommissioning, waste minimization and waste management issues of graphite-moderated reactors already into account when designing new V/HTR concepts.JRC.DDG.F.4-Safety of future nuclear reactor