Livre blanc du Tritium & bilan des rejets de tritium pour les INB
Fusion reactors are seen as a possible energy-generation option in the future (unclear exactly when). The ITER research facility which will provide data for the design of a prototype fusion production reactor is due to be commissioned in 2019 for the non-nuclear phase and to enter nuclear phase in approximately 2025. It will have a process inventory of approximately 1 kg of tritium (358 PBq). No tritium release permits have yet been issued. The ITER design incorporates the notion of defence in depth in its operating methods, with respect to tritium, which is the fuel in the machine. This means that multiple static confinement barriers and dynamic confinement systems are planned, including detritiation and atmosphere treatment at source, limits on the water quantities allowed and water recycling and detritiation. One whole facility is entirely dedicated to tritium, to injecting the deuterium-tritium mixture into the tokamak, and to extracting, recovering and purifying the tritium for reuse. The feasibility of decommissioning was incorporated at design phase. It takes into account the classification of the waste generated – VLLW, L/ILW and LLILW, the outlet channels available and the availability of the site for interim storage of its operational waste. The facility follows the guidelines of the French National Plan for the management of radioactive substances and waste (PNGMDR). Recommendations from the “Tritium Impact” working group In conclusion, the working group puts forward the following recommendations and observations. Management of the current processes enables discharges from all facilities to be recorded and calculated; for the La Manche storage centre, work to characterise the source and the transfers to outlet sources should be improved and these predictions need to be reinforced with measurement data. Detritiation in PWR reactors in NPPs would only have a limited effect on the radiological impact is not currently achievable at an acceptable cost. The associations ACRO and ANCLI are opposed to the use of new fuels, on the basis of the precautionary principle, for as long as doubts remain as to the tritium impact. Detritiation is not achievable in the La Hague plant with the best technologies currently available and in any case it would only have a limited effect on the radiological impact. The discharge/waste strategy to promote tritium storage and recovery at an acceptable cost could only be considered for materials with high-level tritium activity. The associations ACRO and ANCLI are requesting that the oldest fuels be prioritised for reprocessing in order to limit releases, but AREVA and EDF consider that the practice is optimised in this respect. In the view of ACRO and ANCLI, a reduction in tritium production from civilian and military facilities is required. Absolute containment of tritium is an issue that is both technical and financial and determines the development of containers. Tritiated waste management in future repositories will require specific permits, enabling the tritium to be appropriately accounted. Specific management schemes should be accessible for small producers. Assessment of the tritium impact of above-ground repositories requires continuous improvement of the knowledge of source terms, the various transfer pathways from the waste and the associated transfer processes, and also requires the relative weight of the various transfer pathways to be quantified according to the technical solutions selected. Dedicated interim storage facilities to allow tritiated waste from various sources to decay should be put into service, in accordance with the Decree pursuant to the French National Plan for the management of radioactive substances and waste (PNGMDR 2007-2009). The development of detritiation work carried out on behalf of ITER should be monitored.