Critical Issues for Disposal, Recycling, and Clearance of Fusion Radioactive Materials: the European Viewpoint

In order to maximize the environmental benefits of fusion power generation, it is important to clearly define the parameters governing the back-end of the materials cycle. A fusion-specific approach is necessary. Recycling of materials and clearance (i.e. declassification to non-radioactive material) are the two recommended options for reducing the amount of fusion waste, while the disposal as low-level waste could be an alternative route for specific materials and components. Most fusion materials could potentially be recycled or cleared, providing the necessary studies and developments are carried out. To enhance prospects for a successful waste management scheme, we identified the key issues and challenges for disposal, recycling, and clearance, focusing on the EU studie

Some technological problems of fusion materials management

Within the framework of the International Energy Agency Program on Environmental, Safety and Economic Aspects of Fusion Power, an international collaborative study on management of fusion radioactive materials has been carried out to examine the back-end of the materials cycle. The trategy for handling fusion activated materials calls for three potential schemes: clearance, recycling and disposal. There is a growing international effort to avoid geologic disposal, for fusion in particular. Plasma facing components (divertor and blanket) usually contain high radioactivity and are not clearable. As clearance of sizeable components (such as biological shield, cryostat vessel, vacuum vessel, and some constituents of magnets) is highly desirable, we identified the source of radioisotopes that hinder the clearance of these components and investigated the impact of impurity control. Another study assessed radioactivity build up under repeated use of the divertor made of W- La203 alloy. Effect of impurities on activated materials management is illustrated by the examples of 14C generation and impurities activation in concrete of biological shield. We think that consideration of activated materials management scenarios presented in this paper by example of blanket and divertor replacement is of interest as wel

Some technological problems of fusion materials management

Within the framework of the International Energy Agency Program on Environmental, Safety and Economic Aspects of Fusion Power, an international collaborative study on management of fusion radioactive materials has been carried out to examine the back-end of the materials cycle. The trategy for handling fusion activated materials calls for three potential schemes: clearance, recycling and disposal. There is a growing international effort to avoid geologic disposal, for fusion in particular. Plasma facing components (divertor and blanket) usually contain high radioactivity and are not clearable. As clearance of sizeable components (such as biological shield, cryostat vessel, vacuum vessel, and some constituents of magnets) is highly desirable, we identified the source of radioisotopes that hinder the clearance of these components and investigated the impact of impurity control. Another study assessed radioactivity build up under repeated use of the divertor made of W- La203 alloy. Effect of impurities on activated materials management is illustrated by the examples of 14C generation and impurities activation in concrete of biological shield. We think that consideration of activated materials management scenarios presented in this paper by example of blanket and divertor replacement is of interest as well

Recycling of Vanadium Alloys in Fusion Reactors

The feasibility of reprocessing a vanadium alloy after its use as a structural material in a fusion reactor, in order to enable its subsequent hands-on recycling within the nuclear industry, has been determined. For less neutron-exposed components, clearance of materials has also been considered. A conceptual model for the radiochemical processing of the alloy has been developed and tested experimentally. Using di-2-ethyl-hexyl-phosphoric acid it is possible to purify the components of the V-Cr-Ti alloy after its exposure in a fusion reactor down to the required level of activation product concentration

Open Technological Questions Of The Back-End Of The Fusion Materials Cycle

Within the framework of the International Energy Agency (IEA), an international collaborative study on fusion radioactive waste has been carried out over the past several years to examine the back-end of the material cycle. This activity is important to maximize the environmental benefits of fusion as a source of energy. Fusion devices have certain characteristics that make them environmentally friendly devices. In previous studies, an integrated approach to the management of fusion materials back-end was proposed, starting from the removal of components from the power plant, to the reuse of materials through recycling and clearance, or the disposal of the low-level waste in repositories. Recycling and clearance procedures pose many technical questions. Several important technology-related issues were identified and are presented. The paper discusses these issues and considers the requirements to the materials and components permitting their clearance or recyclin

The Back-End of Fusion Materials Cycle: Recycling, Clearance And Disposal

In order to maximize the environmental benefits of fusion power generation, it is important to clearly define the parameters governing the back-end of the materials cycle. A fusion-specific approach is necessary and needs to be developed. Recycling of materials and clearance (i.e. declassification to non-radioactive material) are the two recommended options for reducing the amount of fusion waste, while the disposal as low-level waste could be an alternative route for specific materials and components. Both recycling and clearance criteria have been recently revised by national and international institutions. These revisions and their consequences for fusion material management are examined in this paper. It is also important to define the various processes and routes to avoid generating active waste from fusion as much as possible. Two ways are explored within the fusion community: first, the development of materials leading to low activation levels, avoiding the generation of long lived radionuclides through a strict control of the impurity content in materials; second, the development of suitable and reliable processes allowing either clearance of as much material as possible (potentially after adequate treatment) or recycling most of the remaining materials within the nuclear industry

The Back-End of the Fusion Materials Cycle

Within the framework of the International Energy Agency, an international collaborative study on fusion radioactive waste has been initiated to examine the back end of the materials cycle as an important stage in maximizing the environmental benefits of fusion as an energy provider. The study addresses the management procedures for radioactive materials following the changeout of replaceable components and decommissioning of fusion facilities. We define this as "the back end" of the fusion materials cycle. It includes all the procedures necessary to manage spent radioactive materials from fusion facilities, from the removal of the components from the device to the reuse of these components through recycling/ clearance, or to the disposal of the waste in geological repositories. Fusion devices have certain characteristics that make them environmentally friendly devices; minimization of long-lived waste that could be a burden for future generations is one of these characteristics. Recycling and clearance procedures and regulations have been recently revised, and the effects of these revisions on back-end fusion materials are examined in the paper. Finally, an integrated approach to the management of back-end fusion materials is proposed, and its application to three fusion reactor designs is discussed

Investigations of adsorption states of protium and deuterium in redeposited carbon flakes formed in tokamak T-10

10.1016/j.jnucmat.2008.02.072Journal of Nuclear Materials3762152-159JNUM

An integrated approach to the back-end of the fusion materials cycle

In order to maximise the environmental benefits of fusion power generation, it is important to clearly define the parameters governing the back-end of the materials cycle. A fusion-specific, unique approach is necessary and needs to be developed. Recycling of materials and clearance (i.e. declassification to non-radioactive material) are the two recommended options for reducing the amount of fusion waste, while disposal as low-level waste (LLW) could be an alternative route for specific materials and components. Both recycling and clearance criteria have been recently revised by national and international institutions. These revisions and their consequences are examined in this paper. It is also important to define processes and routes to avoid generating active waste from fusion as much as possible. Two ways are explored within the fusion community: first, to develop materials leading to low activation levels and avoiding the generation of long-lived radionuclides (this includes controlling the impurity content of the material); second, to develop suitable and reliable processes allowing either to clear or release as much material as possible (potentially after adequate treatment) or to recycle most of the remaining materials within the fusion and nuclear industr

Activation and clearance of Vanadium Alloys and Beryllium Multipliers in Fusion Reactors

The possibility of clearance of vanadium-chromium-titanium (V-Cr-Ti) alloys is analysed. These alloys after their service in fusion power plants, have the potential to reach clearance if they are purified from activation products. The extraction part of the technological scheme for radiochemical separation of components of irradiated V-Cr-Ti alloy and their purification from metallic activation products, developed earlier, was tested for the first time in laboratory conditions using activated alloy specimens. The replacement of the acid reextraction of V with peroxide and of acid reextraction of Cr with alkaline improved characteristics of the extraction reprocessing. Duration of the V and Cr reextraction was shortened by about an order of magnitude, the output of these alloy components was increased, V purification from rare-earth metals became two times as great, and Cr decontamination from Co increased by two orders of magnitude. Activation of Be contaminated with trace quantities of uranium is an issue: estimation of Be activation in the blanket of the Power Plant Conceptual Study (PPCS) has suggested that traces of U impurity in Be should be removed - or substantially reduced - prior to us