Japanese contribution to the DEMO-R&D program under the Broader Approach activities

Several technical R&D activities mainly related to the blanket materials are newly launched as a part of the Broader Approach (BA) activities, which was initiated by the EU and Japan. According to the common interests for these parties in DEMO, R&Ds on reduced activation ferritic/martensitic (RAFM) steels as structural material, SiC_f/SiC composites as a flow channel insert material and/or alternative structural material, advanced tritium breeders and neutron multipliers, and tritium technology are carried out through the BA DEMO R&D program, in order to establish the technical bases on the blanket materials and the tritium technology required for DEMO design. This paper describes overall schedule of those R&D activities and recent progress in Japan carried out by JAEA as the domestic implementing agency on BA, collaborating with Japanese universities and other research institutes.     

A fuzzy model to control the temperature in the cooling of metal molds with a spray robot

In a die-casting operation, the die spray is the key to quality and productivity, but the die-spray operation depends on parameter settings such as the spray volume and the operator's experience, even when a robot sprayer is used. The purpose of this study was to establish an intelligent system to control the surface temperature of a die with a water-based mist spray. A fuzzy model was applied to determine the optimum mist spray volume. The results generated show a good match with the actual measurements of the rate of the temperature drop versus the spray-mist volume. After the fuzzy analysis, the spray parameters calculated were used to control an actual die temperature experiment conducted on a heated plate model. The fuzzy model constructed by using fundamental experiments allowed the die spray operation to maintain a predetermined spray volume. This work was presented in part at the Fourth International Symposium on Artificial Life and Robotics, Oita, Japan, January 19–22, 1999     

Investigation of nitrate salts for solar latent heat storage

Solar thermal applications require some means of thermal energy storage. Amongst several storage concepts, latent heat storage is quite suitable because of its high storage density and almost constant temperature during charging and discharging. The temperature range between 200 and 300°C is considered to be important for solar total energy systems. In this temperature range, sodium nitrate and its mixed salts with other nitrates including eutectic and off-eutectic salts are candidates.

The present paper deals with heat transfer in a latent heat storage unit utilizing these salts. A method of rough estimation of the thermal conductivity of the storage materials is described, and the temperature history of the storage material experimentally obtained is compared with numerical solutions and found to be in reasonably good agreement.

It is seen that the temperature of the heat transfer surface quickly drops soon after the appearance of a solid phase due to low thermal conductivity of these salts. Ways to avoid this temperature drop are discussed.     

9H-xanthene-2,7-diols as antioxidants for autoxidation of linoleic acid

The antioxidant activities of 9H-xanthene-2,7-diols and α-tocopherol were studied during the oxidation of linoleic acid in a homogeneous solution and in an aqueous micelle dispersion. The antioxidant activities of 9H-xanthene-2,7-diols for both systems were 1.0–2.4 times greater relative to α-tocopherol. In addition, the 1,3,4,5,6,8-hexamethylxanthene-2,7-diol showed less cytotoxicity toward human fibroblasts than did 2,6-di-t-butyl-4-methylphenol.     

Inelastic behaviour of steel under plasticity-creep interaction condition: An interim report of the Bench Mark project by the subcommittee on inelastic analysis and life prediction of high temperature materials, JSMS

Some of the interim results of the Bench Mark Project by the Subcommittee on the Inelastic Analysis and Life Prediction of High Temperature Materials, JSMS, is presented. The purpose of the present bench mark study is to review and evaluate the inelastic constitutive models relevant to material response under the plasticity-creep interaction.By specifying normalized and tempered steel at 600°C, sixteen bench mark problems of four categories are first established: (I) tensile stress-strain relations and creep curves, (II) material response under mixed modes of plastic and creep loading, (III) ratcheting and deformation under program loads, and (IV) cyclic deformation behaviour under the combination of different strain rates. Then, the outline of seventeen inelastic constitutive models of nine types discussed in this project is presented. Finally, the interim results of these bench mark tests are compared with the corresponding predictions of the constitutive models to evaluate their accuracy in simulating the actual behaviour of the material.