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The IFMIF-like fusion neutron sources (FNSs) such as A-FNS and IFMIF-DONES have Li fire risks and the R&D activity for the Li fire risk reduction has been conducted under the IFMIF/EVEDA project. The objectives of this study are to experimentally elucidate humidity condition in air at which no Li fire ignites and the effect of the heat insulator on the Li fire ignition. The experimental set-up was designed and fabricated in order to perform Li fire experiments safely and systematically. Around 1 g of metallic Li samples were heated with and without the heat insulators as an experimental parameter of humidity in air. In this work, no ignition was observed under the less than 0.15 vol% humidity air. The heating experiments with the heat insulators clarified that the reaction between Li and the heat insulators causing Li fire ignition didn’t occur. In conclusion, the results of the present study suggest the conditions of less than 0.15 vol% humidity air and employing the heat insulator of alkaline earth silicate wool are useful for the Li target system of FNSs.

A conceptual design of Advanced Fusion Neutron Source, A-FNS, has been conducted to achieve early realization of fusion-like neutron irradiation test for fusion reactor materials in Japan. A-FNS provides eight test modules to obtain irradiation data for fusion reactor materials. Conceptual design activities on Blanket Functional Materials Test Module (BFMTM), Tritium Release Test Module (TRTM) and Activated Corrosion Products Module (ACPM) were described among the A-FNS test modules. Also, basic concepts of the sub-system cells for the TRTM and the ACPM were also discussed.

Accelerator-driven fusion neutron sources, e.g. Advanced Fusion Neutron Source (A-FNS) and DEMO Oriented Neutron Source (IFMIF-DONES), are being designed, based on the achievements and lessons learnt from the IFMIF/EVEDA project. The purpose of the study is to analytically evaluate the deformation of the lithium free surface, potentially created by the intense beam injection. We have developed a two-dimensional (2-D) fluid model of the “beam-on” target of an IFMIF-type fusion neutron source by extending the phenomenological 2-D model of the Li target flow of the EVEDA Lithium Test Loop (ELTL). We have derived, from the newly developed model, a practical and analytical formula of the thickness of the “beam-on” target in the flow direction with accounting for the beam injection effect. We have also evaluated the thickness of the beam-on target of A-FNS as an example of application of the derived formula. The evaluation indicates that under the reference design conditions of the accelerator and beam-on Li target of A-FNS, the deformation of the free surface of the target by the beam injection is negligibly small. The analytical results presented here may be used for a benchmark of more complicated CFD simulation for the “beam-on” target design of IFMIF-type fusion neutron sources like A-FNS and IFMIF-DONES. Keywords: IFMIF-type fusion neutron source, Design, Liquid lithium target, Beam injection, Free surface, Modeling