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A new European Project has been launched in April 2008 under the 7th EURATOM Framework Programme (FP7-211333), with a duration of four years, addressing the ‘Treatment and Disposal of Irradiated Graphite and other Carbonaceous Waste (CARBOWASTE)’. The objective of this project is the development of best practices in the retrieval, treatment and disposal of irradiated graphite & carbonaceous waste-like structural material e.g. non-graphitised carbon bricks and fuel coatings (pyrocarbon, silicon carbide). It addresses both legacy waste as well as waste from future generations of graphite-based nuclear fuel. After defining the various targets for an integrated waste management, comprehensive analysis of the key stages from in-reactor storage to final disposal will then be undertaken with regard to the most economic, environmental and sustainable options. This will be supported by a characterisation programme to localize the contamination in the microstructure of the irradiated graphite and so more to better understand their origin and the release mechanisms during treatment and disposal. It has been discovered that a significant part of the contamination (including 14C) can be removed by thermal, chemical or even microbiological treatment. The feasibility of the associated processes will be experimentally investigated to determine and optimise the decontamination factors. Reuse of the purified material will also be addressed to close the ‘Graphite Cycle’ for future graphite moderated reactors. The disposal behaviour of graphite and carbonaceous wastes and the improvement of suitable waste packages will be another focus of the programme. The CARBOWASTE project is of major importance for the deployment of HTR as each HTR module generates (during a 60 years operational lifetime) about 5,000 to 10,000 metric tonnes of contaminated graphite containing some Peta-Becquerel of radiocarbon. It is strongly recommended to take decommissioning and waste management issues of graphite-moderated reactors already into account when designing new HTR concepts.

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Radiocarbon (14C) is a key radionuclide in the assessment of the safety of underground geological disposal facilities for radioactive wastes, and the understanding of the 14C behavior in stainless steel may lead to a re-evaluation of the near-surface repository for the disposal of wastes containing this radionuclide in high concentrations. To achieve this objective, leaching experiments were planned for two different scenarios. The first is where the leaching solution, NaOH solution of pH ca. 12 in aerobic conditions, simulates the expected conditions in a cement-based near-surface repository over long time periods. The other one uses an acid solution of 1M H3PO4, which has been proved as a high efficiency chemical removal agent of 14C in graphite. The development of both analytical methods and protocols to measure the release of 14C from the activated steel samples and the speciation in the aqueous and gaseous phase has been undertaken as part of the EC CAST (CArbon-14 Source Term) project. Analytical methods, suitable for identifying and quantifying low molecular weight organic molecules, comprise ion chromatography (IC) and gas chromatography coupled to mass spectrometry (GC-MS); they are described for aqueous and gaseous samples, respectively. In this paper the preparation of leaching experiments to measure the release of 14C and the results obtained are described.