Overview on the management of radioactive waste from fusion facilities: ITER, demonstration machines and power plants

In the absence of official standards and guidelines for nuclear fusion plants, fusion designers adopted, as far as possible, well-established standards for fission-based nuclear power plants (NPPs). This often implies interpretation and/or extrapolation, due to differences in structures, systems and components, materials, safety mitigation systems, risks, etc. This approach could result in the consideration of overconservative measures that might lead to an increase in cost and complexity with limited or negligible improvements. One important topic is the generation of radioactive waste in fusion power plants. Fusion waste is significantly different to fission NPP waste, i.e. the quantity of fusion waste is much larger. However, it mostly comprises low-level waste (LLW) and intermediate level waste (ILW). Notably, the waste does not contain many long-lived isotopes, mainly tritium and other activation isotopes but no-transuranic elements. An important benefit of fusion employing reduced-activation materials is the lower decay heat removal and rapid radioactivity decay overall. The dominant fusion wastes are primarily composed of structural materials, such as different types of steel, including reduced activation ferritic martensitic steels, such as EUROFER97 and F82H, AISI 316L, bainitic, and JK2LB. The relevant long-lived radioisotopes come from alloying elements, such as niobium, molybdenum, nickel, carbon, nitrogen, copper and aluminum and also from uncontrolled impurities (of the same elements, but also, e.g. of potassium and cobalt). After irradiation, these isotopes might preclude disposal in LLW repositories. Fusion power should be able to avoid creating high-level waste, while the volume of fusion ILW and LLW will be significant, both in terms of pure volume and volume per unit of electricity produced. Thus, efforts to recycle and clear are essential to support fusion deployment, reclaim resources (through less ore mining) and minimize the radwaste burden for future generations

The integral dictionary: A lexical network based on componential semantics

The Integral Dictionary is a comprehensive lexical network for French, English, German, Italian, and Spanish. It is based on componential semantics and lexical functions. The network structure superimposes two graphs. A first graph consists of a hierarchy of concepts divided into classes and themes where the words form the terminal nodes of the graph. A second graph links the words together using lexical functions derived from the Meaning-Text theory. We first introduce the lexical network whose database for French words is. comparable in its size to that of WordNet. We then describe two semantic distances to evaluate the proximity of two. words in the graph and to find their distinctive semantic components. Finally, we give examples of applications we developed with it: the search of a word from a definition and the extraction of the semantic features of a text

Waste management plans for ITER

ITER will produce radioactive waste during its operation (arising from the replacement of components and from process and housekeeping waste) and during decommissioning. The waste concerns components that are activated by neutrons of energies up to 14 MeV, and are contaminated by activated corrosion products, activated dust and tritium. Even if the nuclear waste production will start only with the deuterium-deuterium phase, provisions have to be taken now with the design of the ITER facilities that will be used for the treatment and interim storage of the waste, in order to demonstrate that all the ITER waste will be safely manageable with the existing outlets. This demonstration also needs to be provided to the French regulator

Radwaste management aspects of the test blanket systems in ITER

Test Blanket Systems (TBS) will be operated in ITER in order to prepare the next steps towards fusion power generation. After the initial operation in H/He plasmas, the introduction of D and T in ITER will mark the transition to nuclear operation. The significant fusion neutron production will give rise to nuclear heating and tritium breeding in the in-vessel part of the TBS. The management of the activated and tritiated structures of the TBS from operation in ITER is described. The TBS specific features like tritium breeding and power conversion at elevated temperatures, and the use of novel materials require a dedicated approach, which could be different to that needed for the other ITER equipment