Arai, Masaji; Tamura, Itaru; Hazawa, Tomoya
JAEA-Technology 2015-010, 52 Pages, 2015/05
In the Department of Research Reactor and Tandem Accelerator, developments of high-performance CNS moderator vessel that can produce cold neutron intensity about two times higher compared to the existing vessel have been performed in the second medium term plans. We compiled this report about the technological development to solve several problems with the design and manufacture of new vessel. In the present study, design strength evaluation, mockup test, simulation for thermo-fluid dynamics of the liquid hydrogen and strength evaluation of the different-material-bonding were studied. By these evaluation results, we verified that the developed new vessel can be applied to CNS moderator vessel of JRR-3.
Hazawa, Tomoya; Tamura, Itaru; Takazawa, Hiromitsu
JAEA-Technology 2008-079, 76 Pages, 2009/01
The Department of Research Reactor and Tandem Accelerator has planned the project of increasing cold neutron intensities by ten times by upgrading the cold neutron guide tubes with super-mirrors also and the moderator cell of cold neutron source. An exchange of the guide tubes requires taking the beam shutter of about 6 ton out of the narrow guide tunnel. The cold neutron guide tubes in the front end are 3 times longer then thermal ones and set very close to the reactor core. Therefore, the work has to be done under a high radiation dose as well as paying close attention to setting the tubes precisely. This report describes the result of study on replacing the Ni-guide tubes with super-mirror guide tubes as the first step of the 10-times upgrading project for cold neutrons.
Hazawa, Tomoya; Nagahori, Kazuhisa; Kusunoki, Tsuyoshi
JAEA-Technology 2006-046, 44 Pages, 2006/10
The moderator cell containing liquid hydrogen is made of stainless steel. The material irradiation lifetime is limited to 7 years due to irradiation brittleness. The survey and design for a renewal moderator cell were conducted with a view to domestic production by the JAEA. It was fabricated and replaced by a domestic company, and the replacement work was completed in February, 2006. Characteristic was measured after exchange, and it had the same performance as the moderator cell made in France, and succeeded in making to domestic production.
Kaneko, Koji; Metoki, Naoto; Hazawa, Tomoya; Nagahori, Kazuhisa; Nakamura, Kiyoshi
Hamon, 16(3), p.177 - 178, 2006/07
The neutron flux and energy spectrum from the renewed cold neutron source was measured at the C2-1 beam port in the guide hall of JRR-3. We confirmed that both the absolute flux of 210n/ms and the shape of energy spectrum were reproduced after the replacement of the liquid hydrogen tank. JAEA has a plan to increase cold neutron flux ten times as strong as that at present by introducing a new type of hydrogen tank and super mirror neutron guide in the next term.
Suzuki, Masatoshi; Hazawa, Tomoya; Ishizaki, Yoichi*; Obara, Michio*; Inada, Katsutoshi*; Yonekawa, Mitsunori*; Wakita, Hiroshi*
JAERI-Tech 2004-060, 153 Pages, 2004/09
The cold neutron source (CNS) at JRR-3 was constructed for the purpose of improving the utilization performance of the reactor along the lines of upgrade program. There are two methods for extracting cold neutrons from a reactor, one is to filter a small fraction of cold neutrons in the Maxwellian spectrum of reactor neutrons while the other is to increase the fraction of cold neutron by inserting a cryogenic moderator. The latter is adopted as CNS facilities at almost all cases, and liquid hydrogen and its cooling system are equipped with a cold neutron source at many neutron facilities just like JRR-3. Cold neutrons generated in a cold source are extracted through a neutron guide tube, and are utilized for the purpose of neutron beam experiments such as neutron scattering which study the structures of atoms and molecules in the materials and life science fields. This report summarizes the operation data and the main technical issues which were recorded in the whole operation period from commencement date in 1989 to March 2004.
Tamura, Itaru; Suzuki, Masatoshi; Hazawa, Tomoya; Moriai, Atsushi; Hori, Naohiko; Sasajima, Fumio; Soyama, Kazuhiko
Nuclear Instruments and Methods in Physics Research A, 529(1-3), p.234 - 237, 2004/08
Thermal neutron guides at JRR-3 reactor have been upgraded from Nickel mirrors to Ni/Ti multilayer supermirrors. We performed the characteristics experiment of neutron beams transmitted through supermirror neutron guides. Neutron fluxes at the end of the thermal neutron guides were measured by the gold foil activation method on March 2003. We have confirmed that neutron fluxes at the end of thermal neutron guide increases by 6 times. The neutron spectra were also measured at the end of the thermal neutron guides by the time-of-flight method. The wavelength range for the neutron beam is extended and the shorter wavelength neutrons, which had been filtered by the characteristics of curved neutron guides before upgrade, were observed. In this paper, we have performed several Monte Carlo simulation codes using the McStas package in the consideration of the performance of fabricated supermirrors and its alignment errors for the purpose of estimation of instruments performance. We discuss the comparison of the experimental results with results of simulation.
Tamura, Itaru; Yamamoto, Kazuyoshi; Hazawa, Tomoya; Yoshinaga, Makio; Komeda, Masao; Sagawa, Hisashi
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no abstracts in English
Tamura, Itaru; Arai, Masaji; Nagahori, Kazuhisa; Hazawa, Tomoya; Sagawa, Hisashi; Wada, Shigeru
no journal, ,
no abstracts in English