Advanced Waste Management Strategies for High Dose Spent Adsorbents

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The Great East Japan Earthquake, on 11 March 2011, triggered a devastating tsunami, leading to the loss of at least 19,000 lives and partial melt down of three boiling water reactors at the Fukushima Dai-ici site (Units 1-3). A key technology need in the site stabilisation, recovery and decommissioning programme at the Fukushima Dai-ici site is the decontamination of water used to cool the damaged reactor cores and ground water infiltrating the damaged reactor buildings. This is achieved by use of commercial inorganic ion exchange materials to strip the radionuclide contaminants in several purpose built facilities, which yield a variety of highly radioactive and dispersible "High Dose Spent Adsorbents". Of key concern is the production of hydrogen from radiation induced degradation of water within the adsorbent material, which poses an explosive hazard. The overarching aim of this project is to improve the passive safety of the high dose spent adsorbents to assure prolonged near surface storage and / or disposal in an engineered facility, in accordance with IAEA Safety Standards for the storage and pre-disposal management of radioactive wastes. To achieve this goal, we will develop novel thermal treatment approaches to transform the wet, granular, and dispersible material into an immobile monolithic form which is chemically and physically stable, eliminating the key hazard of hydrogen production. The approaches developed in this project will address a common need in international decommissioning and civil nuclear energy programmes, in which inorganic ion exchange materials find common application. In particular, the research will provide a route to treat a substantial volume of clinoptilolite waste present on the Sellafield site (classed as intermediate level waste) for which there is no currently accepted treatment route.