Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
C decoupler with burn-up reduction aiming at 1-MW pulsed neutron sourceOi, Motoki; Teshigawara, Makoto; Harada, Masahide; Ikeda, Yujiro
Journal of Nuclear Science and Technology, 56(7), p.573 - 579, 2019/07
Times Cited Count：0 Percentile：0.01(Nuclear Science & Technology)In pulsed neutron sources, a neutron absorber called decoupler is attached to the moderator to sharpen the neutron pulses for achieving good neutron energy resolutions. Cadmium and boron carbide (BC) are widely used as the decoupler materials. However, it is difficult to use BC in MW-class spallation neutron sources owing to high burn-up, which decreases cut-off energy and increase of helium gas swelling. To solve these issues, we introduce the concept of pre-decoupler to reduce neutron absorption in the BC decoupler, which is sandwiched by appropriate neutron absorption materials. Then, we study impacts of the pre-decouplers on BC decoupler in terms of burn-up by performing simplified model calculations. It is shown that neutron absorption in BC is reduced by 60% by using a Cd pre-decoupler without neutron intensity penalty. Moreover, helium gas swelling in BC is restrained to be one-third of the value when not using the pre-decoupler.
Oi, Motoki
Shiki, 43, P. 3, 2019/06
At the J-PARC Materials and Life Science Facility (MLF), we developed an Au-In-Cd alloy as a low activation neutron absorber for reducing the activity of moderator assembly, and put it to practical use in the reflector and moderator. As a method to confirm the distribution of indium in the alloy, pulse neutron imaging method is adopted, and the individual element distribution is measured by focusing on the resonance peak of indium, and the uniformity of the alloy is confirmed.
Iga, Kiminori*; Takada, Hiroshi; *
JAERI-Tech 97-068, 58 Pages, 1998/01
no abstracts in English
Oi, Motoki; Teshigawara, Makoto; Harada, Masahide
no journal, ,
At the spallation neutron source of the Japan Proton Accelerator Complex (J-PARC), the design life of the moderator vessels is 30,000 MWh and we are preparing a moderator vessel for replacement. In the next moderator vessel, Au-In-Cd alloy is used as a decoupler material for short pulse and reducing the residual radio activities. The decoupler is formed by combining spherical surfaces having plural radius. For that reason, we adopted casting for making decouplers. In this study, we explain about fabrication of the Au-In-Cd alloy decoupler.
Oi, Motoki; Inoue, Hiromi*; Teshigawara, Makoto; Harada, Masahide; Ikeda, Yujiro*
no journal, ,
J-PARC Material and Life science experimental facility (MLF) is a pulsed spallation neutron source. There are three types of hydrogen moderators. Two of the moderators are using neutron absorbing material around the moderator which called decoupler. The decoupler is made with Au/Ag-In-Cd alloy. The first moderator assembly is using in the MLF and we are planning to exchange it to the second one in 2023. And now we are manufacturing the 3rd moderator assembly for the future exchange. Recently, due to RoHS directive, it is difficult to make cadmium alloy in the world. Therefor we make Au/Ag-In-Cd alloy by ourselves. For the second moderator assembly, decoupler parts are cut after casting. For the third moderator assembly, NC milling machine is introduced, and surface of the casted parts are milled by the NC machine for good surface condition for good hip bonding. In this presentation, we will mainly report on the production of the Au-In-Cd decoupler for 3rd moderators and reflector.
