DEM and MELT In-Can Thermal Treatment for D and D and Remediation Waste - 21011

Some waste streams arising from decommissioning and dismantling operations need adapted conditioning matrix in accordance with their specific features and with the requirements from the regulations. This is for instance the case of highly active materials remaining in shut down nuclear fuel reprocessing facilities (including legacy waste) as well as miscellaneous secondary waste coming from D and D and remediation operations. The numerous constraints associated with the management of such highly active waste, usually highly loaded with Cs-137, and with potential complex physico-chemical composition, lead to investigate the implementation of an in-situ conditioning treatment able to produce waste packages compliant with existing evacuation routes and/or on-site interim storage facilities. As grouting or cement matrices tend to produce hydrogen by radiolysis due to the high level of activity, or would lead to a significant increase in volume, they do not seem to be relevant. Glass and glass-ceramic matrices are the best candidates to bring a satisfying solution as glassy material and vitrification processes have demonstrated to be adapted to high-level waste and can be flexible enough to accommodate a variable waste stream. In this context, the consortium of the DEM and MELT project which gathers Orano, CEA (French Alternative Energies and Atomic Energy Commission), ECM technologies and ANDRA (French national radioactive waste management agency) has developed a specific In-Can vitrification tool designed to match the requirements and constraints from D and D projects. The DEM and MELT In-Can vitrification process is a robust, simple and versatile in situ vitrification process. It is designed for high or intermediate level waste and is compact enough to be implemented in an existing facility or close to the waste to be treated. It has been developed to treat liquid and solid waste, to produce a small amount of secondary waste and to minimize investment and operating costs. The DEM and MELT project is supported by the French government program 'Programme d'Investissements d'Avenir' Fukushima Daiichi Nuclear Power Station was severely damaged by the tsunami induced by the earthquake on March 11, 2011. A large amount of water treatment secondary waste has been generated from the cleanup of contaminated water coming from reactor buildings. An applicability evaluation of the DEM and MELT technology to Fukushima Daiichi water treatment secondary waste has been performed between 2018 and 2021. This evaluation is a project led by Orano, CEA and ANADEC, and is performed by the funds from the Japanese Ministry of Economy, Trade and Industry as The Subsidy Program 'Project of Decommissioning and Contaminated Water Management'. This paper presents preliminary results from the DEM and MELT applicability evaluation to Fukushima Daiichi water treatment secondary waste. (authors)