No abstract available

[en] The DUNE experiment's goals of precision studies of neutrino oscillations, searches for proton decays, and observation of neutrinos from supernova explosions require low noise electronics for the readout of the time project chamber anodes immersed in liquid Argon. This presentation discusses the design of the readout system for the first DUNE far detector module that uses wire based anode plane assemblies as the sensing element of the TPC, and in particular the chain of custom designed application specific integrated circuits that are used to amplify, digitize, and serialize the signals from the TPC wires. These ASICs are mounted on front-end motherboards that are installed on the APAs inside the cryostat, which is crucial in order to meet the noise specifications of DUNE. This presentation reviews the development of the ASICs and the FEMBs, measurements obtained from standalone prototypes, as well as performance measurements from small scale tests where the FEMBs are installed on APAs operated at cryogenic temperatures.

No abstract available

[en] Beryllides have many interesting properties at high temperature and are candidate materials as advanced neutron multiplier for DEMO Reactor blanket developed by JAERI. A new blanket design with mixed pebble packing of neutron multiplier and tritium breeder has been proposed to improve tritium breeding ratio (TBR). Therefore, it is necessary to evaluate the compatibility between the neutron multiplier and the tritium breeder. In this study, the compatibility between Be₁₂Ti and Li₂TiO₃ was investigated. The compatibility between Be and Li₂TiO₃ was also investigated for the comparison with the case of Be₁₂Ti. When the Be₁₂Ti specimen was placed in contact with Li₂TiO₃, neither reaction products nor diffusion of Li in beryllide were found after annealing during 1000 h at 800 deg. C. In the case of Be specimen in contact with Li₂TiO₃ no reaction products were observed, however, a diffusion of Li into Be was identified after annealing for more than 300 h at 800 deg. C. These results show that the compatibility of Be₁₂Ti with Li₂TiO₃ was higher than that of Be, therefore, from the point of view of compatibility mixed pebble beds of neutron multiplier Be₁₂Ti and tritium breeder Li₂TiO₃ pebbles can be used in a blanket

[en] This paper describes the results of an irradiation study carried out in the Halden boiling water reactor (HBWR). The objective of this irradiation was to clarify the performance of various BWR fuel designs - helium prepressurization (0.3 MPa), pellet shape modification (annular and short-length annular) and barrier cladding (copper and zirconium) - under steady-state and load-follow operations

[en] Be₁₂Ti has a high melting point and good chemical stability and is a promising advanced material for the neutron multiplier of the DEMO reactor that requires temperatures higher than 600 deg. C in a blanket. To evaluate the tritium inventory in the breeding blanket, a tritium release experiment of neutron-irradiated Be₁₂Ti with a total fast fluence of about 4x10²⁰ n/cm² (E>1 MeV) was carried out at 330, 400 and 500 deg. C. It was clear that tritium could be released easier than from beryllium, and the apparent diffusion coefficient in Be₁₂Ti was about two orders larger than that in beryllium at 600-100 deg. C. In addition to the good tritium release property, the swelling calculated from the density change of the specimens up to 1100 deg. C in this test was smaller than that of beryllium

[en] Beryllides have good properties and are one of the candidate materials for the neutron multiplier of the DEMO reactor in which good performance is required at 600-800 deg. C. Therefore, a good compatibility with structural materials is expected for the beryllides. In this study, a compatibility test between Be₁₂Ti and SS316LN was carried out as first step to evaluate the compatibility between beryllides and structural materials. The thickness of the reaction layer between Be₁₂Ti and SS316LN at 800 deg. C after 1000 h was approximately 30 μm, whereas that of beryllium metal was 300 μm. At 600 deg. C after 1000 h, the thickness of the reaction layers as to Be₁₂Ti and Be was less than 10 and 100 μm, respectively. The compatibility between Be₁₂Ti and SS316LN was evaluated and Be₁₂Ti was perfectly better than that between beryllium metal and SS316LN at high temperature (600-800 deg. C). The advantage of beryllides as a neutron multiplier in the Demo reactor was proved

[en] Beryllides are expected to be used as the advanced neutron multiplier for the DEMO blanket owing to their peculiar properties like higher melting point, high oxidation resistance, etc. which can improve the blanket design. In this study, thermal conductivity of neutron irradiated Be₁₂Ti was measured. The Be₁₂Ti specimens were fabricated by HIP process using beryllium and titanium powder, and were irradiated in the JMTR up to a fast neutron fluence (E>1 MeV) of 4x10²⁰ n/cm² at temperatures of 330, 400 and 500 deg. C. Thermal diffusivity and specific heat of un-irradiated and irradiated specimens were measured up to 1000 deg. C by laser flash method. Then, the thermal conductivity was evaluated from these data. The effective thermal conductivity in the pebble bed of fusion blanket was also estimated and interesting prospects for blanket design were obtained

[en] Titanium beryllides such as Be₁₂Ti are considered to be promising alternatives to beryllium as the neutron multiplier. Thus, the authors investigated the reactivity of Be₁₂Ti with water vapor. In the experiments, the Be₁₂Ti sample was exposed to a gas containing water vapor of 10 000 ppm at temperatures as high as 1000 deg. C. Chaotic breakaway reactions were not observed for the Be₁₂Ti sample, and the amount of hydrogen generated was found to be far smaller in comparison with beryllium. Thus, it can be said that Be₁₂Ti is less reactive with water vapor, which is a great merit for the neutron multiplier

[en] As a part of computer code development programs on severe accident analysis, computer programs HORN and REMOVAL, are being developed for analysis of fission product release and transport in primary coolant system and containment vessel. HORN is designed to calculate fission product release and transport in primary coolant system and the code is capable of predicting chemical forms of volatile fission product in a leak path based upon equilibrium assumptions. REMOVAL is to calculate aerosol removal by natural mechanism as well as engineered safety features in containment vessel. The model includes steam condensation onto aerosol particles. Results of sensitivity analyses are presented along with description of the models used in each code