M. Sugimoto

IFMIF: overview of the validation activities

The Engineering Validation and Engineering Design Activities (EVEDA) for the International Fusion Materials Irradiation Facility (IFMIF), an international collaboration under the Broader Approach Agreement between Japan Government and EURATOM, aims at allowing a rapid construction phase of IFMIF in due time with an understanding of the cost involved. The three main facilities of IFMIF (1) the Accelerator Facility, (2) the Target Facility and (3) the Test Facility are the subject of validation activities that include the construction of either full scale prototypes or smartly devised scaled down facilities that will allow a straightforward extrapolation to IFMIF needs. By July 2013, the engineering design activities of IFMIF matured with the delivery of an Intermediate IFMIF Engineering Design Report (IIEDR) supported by experimental results. The installation of a Linac of 1.125 MW (125 mA and 9 MeV) of deuterons started in March 2013 in Rokkasho (Japan). The worlds largest liquid Li test loop is running in Oarai (Japan) with an ambitious experimental programme for the years ahead. A full scale high flux test module that will house ~1000 small specimens developed jointly in Europe and Japan for the Fusion programme has been constructed by KIT (Karlsruhe) together with its He gas cooling loop. A full scale medium flux test module to carry out on-line creep measurement has been validated by CRPP (Villigen).

The accomplishment of the Engineering Design Activities of IFMIF/EVEDA: The European-Japanese project towards a Li(d,xn) fusion relevant neutron source

The International Fusion Materials Irradiation Facility (IFMIF), presently in its Engineering Validation and Engineering Design Activities (EVEDA) phase under the frame of the Broader Approach Agreement between Europe and Japan, accomplished in summer 2013, on schedule, its EDA phase with the release of the engineering design report of the IFMIF plant, which is here described. Many improvements of the design from former phases are implemented, particularly a reduction of beam losses and operational costs thanks to the superconducting accelerator concept, the re-location of the quench tank outside the test cell (TC) with a reduction of tritium inventory and a simplification on its replacement in case of failure, the separation of the irradiation modules from the shielding block gaining irradiation flexibility and enhancement of the remote handling equipment reliability and cost reduction, and the water cooling of the liner and biological shielding of the TC, enhancing the efficiency and economy of the related sub-systems. In addition, the maintenance strategy has been modified to allow a shorter yearly stop of the irradiation operations and a more careful management of the irradiated samples. The design of the IFMIF plant is intimately linked with the EVA phase carried out since the entry into force of IFMIF/EVEDA in June 2007. These last activities and their on-going accomplishment have been thoroughly described elsewhere (Knaster J et al [19]), which, combined with the present paper, allows a clear understanding of the maturity of the European–Japanese international efforts. This released IFMIF Intermediate Engineering Design Report (IIEDR), which could be complemented if required concurrently with the outcome of the on-going EVA, will allow decision making on its construction and/or serve as the basis for the definition of the next step, aligned with the evolving needs of our fusion community.

IFMIF: Steps toward realization

The world fusion programme needs within next two decades the results of two large facilities in the race towards commercial fusion power plants based on plasma magnetic confinement. ITER, presently under construction in the South of France will teach us how to control stable deuterium-tritium nuclear fusion reactions. In turn, IFMIF will allow the qualification and characterization of the materials for the first wall of the reactor vessel. The first wall, a combination of layers of different specialized materials that aims to maximize the conversion of neutrons into thermal energy and breed tritium to fuel the fusion reactions, must be capable to withstand structural damage of up to 150 displacements per atom in the metal lattice of purposely designed RAFM (Reduced Activation Ferritic-Martensitic) steels. The 14.1 MeV energy of fusion neutrons makes existing neutron sources (namely fission reactors and spallation facilities) not fully suitable to reproduce experimentally the degradation of mechanical properties of the candidate materials. IFMIF will generate a neutron flux of 10̂18/m2·s with a broad energy peak at around 14 MeV through (d, Li)n stripping reactions. Two deuteron accelerators with 125 mA, 40 MeV beams and a footprint of 20 cm × 5 cm will impact a liquid Lithium screen flowing at 15 m/s. The neutrons generated will irradiate test modules at different levels of neutron fluxes. Of particular relevance will be the 0.5 l of the High Flux Test Module where miniaturised specimens, presently under qualification, will be tested at various controlled temperatures to reach within a few years the same conditions as the first wall of a commercial reactor vessel. IFMIF, presently in its Engineering Validation and Engineering Design Activities (EVEDA) phase, is overcoming the technical challenges with three main prototyping activities: 1) the world largest liquid Lithium loop, presently under operation in Oarai (Japan); 2) different prototypes of the High Flux Test Module and its cooling loop to independently control the testing temperature in Karlsruhe (Germany) and 3) a deuteron Linac at 125 mA and 9 MeV, which installation starts in March 2013 in Rokkasho (Japan).