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Maekawa, Fujio; Oikawa, Kenichi; Tamura, Masaya; Harada, Masahide; Ikeda, Yujiro; Watanabe, Noboru
LA-UR-06-3904, Vol.1, p.129 - 138, 2006/06
Total 23 neutron beam-lines will be installed for JSNS in the J-PARC project. One of them is assigned for the Materials and Life Science Facility (MLF), and the MLF will construct a neutron beam-line to demonstrate and monitor neutronic performance of JSNS. The neutron beam-line was accordingly named as "Neutron Beam-line for Obserbation and Research Use (NOBORU)". Major parts of the NOBORU, i.e., beam ducts, shield, a beam stop, slits, a cabin for measurement, a pillar crane, a sample table, etc., have been ordered in March 2004, and installation will be completed in 2007. A T0 chopper, a frame-overlap chopper, detector systems, samples, etc. will be ordered later on. The sample position is at 14 m from the decoupled moderator. Approximate sample room dimensions are 3 
2.5 m in area and 3 m in height. A shield structure was determined by shielding calculations in which detailed 3-D structure was considered. The design of NOBORU will be presented in the session.
Oikawa, Kenichi; Maekawa, Fujio; Tamura, Masaya; Harada, Masahide; Kato, Takashi; Ikeda, Yujiro; Niita, Koji*
LA-UR-06-3904, Vol.2, p.139 - 145, 2006/06
A preliminary investigation on a satellite building for a long-beamline instrument of MLF is now in progress. In order to estimate the total cost of the building, we started the shielding analysis of the beamline using MCNPX and PHITS, where the latest beamline design and the neutron spectrum have been adopted.
Harada, Masahide; Watanabe, Noboru; Teshigawara, Makoto; Kai, Tetsuya; Maekawa, Fujio; Kato, Takashi; Ikeda, Yujiro
LA-UR-06-3904, Vol.2, p.700 - 709, 2006/06
Pulse characteristics data for every neutron beam line are indispensable in designing devices for neutron scattering experiments of JSNS. A detailed model was built and pulse characteristics of each beam line were estimated using the PHITS code and the MCNP-4C code. These results have been disclosed on the J-PARC homepage since September 2004. Due to changes of moderator shapes in a progress of manufacture design, we observed from the calculation that pulse structures of decoupled moderators were deteriorated, especially, those of pulse tail. We found that this deterioration was caused by leakage neutron from gaps between decouplers and absorbing liners of the reflector. For a final stage of the manufacture design, we carefully tried to find other factors which deteriorated the pulse characteristics. Furthermore, pulse structures of poisoned and unpoisoned decoupled moderators were evaluated with the consideration of heterogeneous burn-up and leakage neutron spectra including high-energy region up to GeV were estimated for each neutron beam hole.
Tatsumoto, Hideki; Kato, Takashi; Aso, Tomokazu; Hasegawa, Shoichi; Ushijima, Isamu*; Otsu, Kiichi*; Ikeda, Yujiro
LA-UR-06-3904, Vol.2, p.426 - 434, 2006/06
In JSNS, Cadmium has been selected as a poison material in a hydrogen moderator to obtain narrow neutron pulse. The concern to adopt to Cd is how to bond Cd and Al alloy plate. R&Ds for bonding have been performed. But good bonding has not been obtained. Consequently, heat transfer between Cd poison and cryogenic hydrogen was studied for the case of insufficient bonding. The heat transfers for various bonding ratios were analyzed by CFD code (STAR-CD) without any turbulence model. The temperature rise in Cd poison for insufficient bonding was estimated. As a result, even the case of the bonding ratio of only 5 %, the maximum temperature of Cd is around 75K. Therefore, the expected heat transfer between the Cd poison and the hydrogen should be sufficient for insufficient bonding. Then, it is found that the any bonding method should be available for manufacturing method of Cd poison.
Hasegawa, Shoichi; Kato, Takashi; Aso, Tomokazu; Ushijima, Isamu*; Tatsumoto, Hideki; Otsu, Kiichi*; Ikeda, Yujiro
LA-UR-06-3904, Vol.2, p.402 - 407, 2006/06
In JSNS, the hydrogen of super critical state is adopted as moderators. Therefore the cryogenic hydrogen system is prepared, which consists of hydrogen circulating unit and transfer lines to moderators. The hydrogen system will immediately discharge hydrogen when an off-normal event occurs. In case of emergency, helium gas will be inputted to an insulation vacuum of the transfer line in order to enhance the heat transfer and the hydrogen discharge time should be shortened. Then, it is impotant to estimate the behaviour of pressure and velocity of discharging hydrogen in the emergency. During hydrogen discharge, the pressure rise in the discharge piping should be kept below the design pressure of 0.1 MPa. The result of analysis shows that the pressure of helium gas injection is suitable less than 0.04Mpa, and that the maximum hydrogen discharge flow is evaluated to be 0.047 kg/s after around 150 seconds. After five minutes with this condition, the hydrogen of around 90% in the moderator piping is discharged. Safety hydrogen release in the case of emergency can be established.
Aso, Tomokazu; Monde, Masanori*; Sato, Hiroshi; Tatsumoto, Hideki; Kato, Takashi; Ikeda, Yujiro
LA-UR-06-3904, Vol.2, p.385 - 394, 2006/06
no abstracts in English