Development of the Water Cooled Ceramic Breeder Test Blanket Module in Japan

The development of a Water Cooled Ceramic Breeder (WCCB) Test Blanket Module (TBM) is being performed as one of the most important steps toward DEMO blanket in Japan. For the TBM testing and evaluation toward DEMO blanket, the module fabrication technology development by a candidate structural material, reduced activation martensitic/ferritic steel, F82H, is one of the most critical items from the viewpoint of realization of TBM testing in ITER. In Japan, fabrication of a real scale first wall, side walls, a breeder pebble bed box and assembling of the first wall and side walls have succeeded. Recently, the real scale partial mockup of the back wall was fabricated. The fabrication procedure of the back wall, whose thickness is up to 90 mm, was confirmed toward the fabrication of the real scale back wall by F82H. Important key technologies are almost clarified for the fabrication of the real scale TBM module mockup. From the view point of testing and evaluation, development of the technology of the blanket tritium recovery, development of advanced breeder and multiplier pebbles and the development of the blanket neutronics measurement technology are also performed. Also, tritium production and recovery test using D-T neutron in the Fusion Neutronics Source (FNS) facility has been started as the verification test of tritium production performance. This paper overviews the recent achievements of the development of the WCCB TBM in Japan.     

Conceptual study of vertical sector transport maintenance for DEMO fusion reactor

The maintenance scheme is a critical issue for DEMO design, and requires high availability of the reactor. The SlimCS, designed in JAEA, adopts the horizontal sector transport hot cell maintenance scheme. In order to determine the most appropriate DEMO reactor maintenance scheme, it is important to assess the various maintenance schemes. In this paper the vertical sector transport maintenance concept is proposed for the first time. In the sector maintenance scheme, the amount of cutting/re-welding of the piping is minimized. The sector including blanket modules and a high-temperature shield was divided into 10° segments in a toroidal direction. The sectors are designed to be removed and re-inserted through upper alternate vertical maintenance ports. In the case of the vertical sector transport maintenance scheme, inter-coil structures could be adopted for use against turnover force in toroidal field (TF) coils. This shows an advantage in DEMO maintenance compared with horizontal sector transport.     

Evaluation of local deformation behavior accompanying fatigue damage in F82H welded joint specimens by using digital image correlation

By using digital image correlation, the deformation behaviors of local domains of F82H joint specimens welded using tungsten inert gas (TIG) and electron beam (EB) welding were evaluated during tensile and fatigue testing. In the tensile test specimens, the tensile strength decreased in the TIG-welded joints, and ductility decreased in both the EB- and TIG-welded joints. Because axial strain increased in the tempered heat-affected zone (HAZ) and led to the fracture of the TIG-welded joint, the strength was considered to have decreased because of welding. In fatigue testing, the number of cycles to fracture for the welded joint decreased to less than 40–60% of that for the base metal. For both fracture specimens, the largest value of shear strain was observed in the region approximately between the fine-grained HAZ and tempered HAZ; this shear strain ultimately led to fracture. Cavities and macrocracks were observed in the fine-grained HAZ and tempered HAZ in the cross sections of the fracture specimens, and geometrical damage possibly resulted in the reduction of fatigue lifetime.     

Developments of new concept analytical instruments for failure analyses of sub-100 nm devices

We have developed analytical instruments based on new concepts for failure analyses of devices of 100 nm dimensions or less. They are a sputtered neutral mass spectrometer with focused ion beam for highly sensitive element analysis in microarea (10¹⁸ atoms/cm³ in 30 nm area), transmission electron microscope (TEM) with electron energy loss spectrometer for chemical bond analysis in less than 2 nm area, Nanoprober for electrical characteristics inspection in actual circuits, computed tomography-TEM for three-dimensional observation of crystalline defect with 1 nm spatial resolution, atmospheric pressure ionization mass spectrometer for trace impurities ppq (parts per quadrillion) analysis in gases, and glow discharge optical emission spectrometer for rapid and precise composition analysis. Using these instruments, it was found that the formation of SiO₂ or TiO_x film by water from titanic acid (TiO_x·H₂O) is the cause of the high resistivity in a contact (CVD-W/CVD-TiN/Ti/Si) and vaporization of silicon dioxide by phosphorus trifluoride (PF₃) is the cause of voids in interlayer dielectric film borophosphosilicate glass.     

CO2 Sensing Property of CuO-BaTiO3 Mixed Oxide Film Prepared by Self-Assembled Multibilayer Film as a Precursor

Preparation of CuO-BaTiO₃ mixed oxide thin film by the decomposition of a self-assembled multibilayer film as a molecular template was investigated in this study. Furthermore, CO₂ sensing property of the resultant thin film was investigated as a capacitive type sensor. The self-assembled bilayer film of few 1000 layers thickness can be obtained easily by casting an aqueous suspension consisting of dimethyldihexadecylammoiun bromide (DC1-16), Cu(ClO₄)₂, Ba(TiO(C₂H₄)₂), 2,6-dimetyle-3,5heptadione (DHP), and polyvinyl alcohol. Divalent copper ion (Cu²⁺)) which is associated with 2 DHP molecules was incorporated into the molecular bilayer film and BaTiO₃ precursor exists at the interspace of molecular bilayer film by coordinating with polyvinyl alcohol. Upquenching the organic-inorganic film at 1173 K leads to the uniform film of CuO-BaTiO₃ oxide mixture. Although operating temperature shifted to higher temperature, the resultant film exhibits the capacitance change upon exposure to CO₂. Consequently, it is concluded that the mixed oxide film of CuO-BaTiO₃ prepared by the decomposition of multibilayer film was also an appropriate capacitive type CO₂ sensor.     

In-vitro heat-generating and apatite-forming abilities of PMMA bone cement containing TiO2 and Fe3O4

Poly (methyl methacrylate) (PMMA) bone cement is widely used as a filler for repairing bone defects. To improve the effectiveness of the treatment for bone defects caused by metastatic bone tumours, we propose the formulation of PMMA cement containing titania (TiO₂) and magnetite (Fe₃O₄) that offers high bone affinity, making the cement suitable for use in magnetic hyperthermia. The TiO₂ and Fe₃O₄ contents of the PMMA cement varied from 20 to 45 mass%. The various cement samples were evaluated for their apatite-forming ability and heat-generation characteristics. The samples containing TiO₂ in concentrations of 15 mass% or higher formed apatite on their surfaces within 14 days in a simulated body fluid. The heat-generation characteristics of the samples were evaluated by applying an alternating current (AC) magnetic field under the following conditions: |H| = 40 Oe and f = 600 kHz, or |H| = 100 Oe and f = 100 kHz. The surface temperatures of the samples containing 25 and 30 mass% Fe₃O₄ reached 42.3 and 44.8 °C, respectively, at |H| = 40 Oe and f = 600 kHz. During hyperthermia treatment, cancer cells die at temperatures higher than 42 °C, and the cement samples fabricated in this study could reach this temperature. However, since some degree of heat loss will occur in vivo, it is necessary to ensure that the temperature is higher than 42 °C by varying the AC magnetic field. Nevertheless, the fact that the samples containing Fe₃O₄ concentrations of 25 mass% or higher generated enough heat under the AC magnetic field makes them suitable for clinical use in hyperthermia. Thus, PMMA cement containing 15 mass% or more of TiO₂ and 25 mass% or more of Fe₃O₄ should be investigated as a bioactive bone cement with a strong hyperthermia effect.     

Filter with variable transmission characteristics for determination of three-dimensional roughness

In this study, we propose a low-pass filter whose transmission characteristics are determined to be more than 99.99% identical to the designed transmission characteristics at wavelengths greater than the cut-off wavelength. This low-pass filter is realized using a frequency-domain method which uses down-sampling, a frequency filter, and a cubic B-spline. When the frequency characteristics of a Gaussian filter (GF) were used as the designed transmission characteristics, this low-pass filter perfectly replaced the GF. In addition, no end effects and directional characteristics developed, and high-speed computation was possible. Furthermore, we can easily realize a low-pass filter having transmission characteristics that rise sharply at a right angle like a step edge.     

Preparation of monodispersed polymer-modified silica particles by radical polymerization using silica colloid and introduction of functional groups on the composite surface

Summary Radical polymerizations of vinyl monomers using a initiator of 2,2-azobis(2-amidinopropane) dihydrochloride on monodispersed silica colloid led to formation of spherical polymer/SiO₂ composites, retained particle size. Addition of hydroxypropyl cellulose to the reaction system resulted in yielding excellent dispersible composites into ethanol by short period ultrasonic irradiation. The polymerization of styrene in the presence of mercapto-amine or carboxylic acid derivatives could successfully introduce amino or carboxyl group on the Poly(styrene)/SiO₂ composite.     

Tobit model analysis of mutations causing haemophilia

Haemophilia A is a genetic disease resulting from deficiency of factor VIII. The database of mutations causing haemophilia A has been developed by the worldwide collaboration. In this study, we predicted the severity of haemophilia A using ordinary least squares regression (OLS) and Tobit model regression in factor VIII. As parameters, we used four physical–chemical parameters of amino acids and the accessible surface area. As the result, there is a difference between OLS and Tobit model analysis in the prediction of haemophilia A severity. We found that the predicted value by Tobit model in severe data is close to the observed value. These results suggest that Tobit model regression analysis is superior to estimating severity of haemophilia A in severe data than OLS.