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Tokunaga, Sho; Horiguchi, Hironori; Nakamura, Takemi
JAEA-Technology 2023-001, 37 Pages, 2023/05
JAEA-Technology-2023-001.pdf:1.39MB
The cold neutron source (CNS) of the research reactor JRR-3 converts thermal neutrons generated in the reactor into low-energy cold neutrons by moderating them with liquid hydrogen stored in the moderator cell. Cold neutrons generated by the CNS are transported to experimental instruments using neutron conduits, and are used for many studies of physical properties, mainly in life science, polymer science, environmental science, etc. Improvement of cold neutron intensity is essential to maintain competitiveness with the world's research reactors in neutron science, and we are developing a new CNS that incorporates new knowledge. The current moderator cell for the CNS of JRR-3 is a stainless-steel container which is a canteen bottle type, and the cold neutron intensity can be improved by changing the material and shape. Therefore, the basic specifications of the new moderator cell were changed to aluminum alloy which has a smaller neutron absorption cross section, and the shape was optimized using a Monte Carlo code MCNP. Since these changes in specifications will result in changes in heat generation and heat transfer conditions, the CNS of JRR-3 was re-evaluated in terms of self-regulating characteristic, heat transport limits, heat resistance and pressure resistance, etc., to confirm its feasibility in thermal-hydraulic design. This report summarizes the results of the thermal-hydraulic design evaluation of the new moderator cell.
Takada, Hiroshi
Kasokuki Handobukku, p.330 - 333, 2018/04
Spallation neutron source provides thermal and cold neutrons for materials researches. Those neutrons are obtained by slowing down the neutrons generated in a neutron production target by injecting high energy protons in surrounding reflector and moderators. This article introduces basic characteristics of the neutron production target at first, and then explains the characteristics of moderator, especially the design to generate high intensity and high quality neutron pulses with narrow width in the moderators used in the 1-MW spallation neutron source at J-PARC. Furthermore, the design procedure of the spallation neutron source is described.
Sato, Hiroshi; Aso, Tomokazu; Kogawa, Hiroyuki; Teshigawara, Makoto; Hino, Ryutaro
JAERI-Tech 2004-018, 23 Pages, 2004/03
JAERI-Tech-2004-018.pdf:2.42MB
The Japan Atomic Energy Research Institute is constructing a mega-watt class spallation neutron source in cooperation with the High Energy Accelerator Research Organization. A cold moderator using liquid hydrogen is one of the key components in the system, which directly affects the neutronic performance both in intensity and pulse time structure. Since a hydrogen temperature rise in the moderator vessel affects the neutronic performance, it is necessary to suppress the recirculation and stagnant regions which would cause hot spots. A cold moderator with a poison plate (poisoned decoupled moderator) has a high possibility to generate the stagnant region on and near the poison plate. Thermal-hydraulic analyses were carried out with proposed inner structure of the poisoned cold moderator. The stagnant and recirculation regions could be reduced by making a gap between the poison plate end and the vessel bottom surface, and the local temperature rise also could be kept under the required design value.
Kogawa, Hiroyuki; Ishikura, Shuichi*; Hino, Ryutaro; Kato, Takashi; Aso, Tomokazu; Sato, Hiroshi; Harada, Masahide; Kai, Tetsuya; Teshigawara, Makoto; Maekawa, Fujio; et al.
Proceedings of ICANS-XVI, Volume 2, p.635 - 644, 2003/07
no abstracts in English
Kumai, Toshio; Liem, P. H.*; Horiguchi, Yoji
JAERI-Tech 2002-023, 49 Pages, 2002/03
no abstracts in English
Aso, Tomokazu; Kaminaga, Masanori; Terada, Atsuhiko*; Hino, Ryutaro
JAERI-Tech 2001-051, 22 Pages, 2001/08
JAERI-Tech-2001-051.pdf:4.51MB
no abstracts in English
Kritmaitree, P.*; Akiyama, Mitsunobu*; Hino, Ryutaro; Kaminaga, Masanori; Terada, Atsuhiko*
Journal of Nuclear Science and Technology, 37(11), p.996 - 998, 2000/11
no abstracts in English
Iga, Kiminori*; Takada, Hiroshi; *
JAERI-Tech 97-068, 58 Pages, 1998/01
no abstracts in English
Aso, Tomokazu; Ishikura, Shuichi*; Teshigawara, Makoto*; Hino, Ryutaro
JAERI-Tech 97-063, 59 Pages, 1997/12
no abstracts in English
Aso, Tomokazu; Teshigawara, Makoto; Hasegawa, Shoichi; Muto, Hideki*; Aoyagi, Katsuhiro*; Takada, Hiroshi; Ikeda, Yujiro
no journal, ,
no abstracts in English
Aso, Tomokazu; Teshigawara, Makoto; Hasegawa, Shoichi; Muto, Hideki*; Aoyagi, Katsuhiro*; Takada, Hiroshi; Ikeda, Yujiro
no journal, ,
no abstracts in English
Teshigawara, Makoto; Aso, Tomokazu; Hasegawa, Shoichi; Muto, Hideki*; Aoyagi, Katsuhiro*; Takada, Hiroshi; Ikeda, Yujiro
no journal, ,
Performance degradation of helium refrigerator was occurred for liquid hydrogen circulation system of J-PARC high intensity neutron source since 2015. In order to find the cause of performance degradation of helium refrigerator, we investigated the impurities in helium gas and accumulated oil in inside cold box components by quadrupole mass spectrometer and organic solvent extraction. The measured impurities and accumulated oil were less than design value. We collected 143g of total amount of accumulated oil from heat exchanger and adosorber, which was corresponded to estimated value from 10 ppb of oil contamination in helium and accumulated operation period. However, we only could find out that accumulated oil like coating film on top surface of felt, which was used to hold the active charcoal in adsorber. We report detailed measurement results of impurities, accumulated oil, etc., to find the cause of performance degradation.
Teshigawara, Makoto; Aso, Tomokazu; Muto, Hideki*; Aoyagi, Katsuhiro*; Takada, Hiroshi; Ikeda, Yujiro
no journal, ,
Performance degradation of helium refrigerator was occurred for liquid hydrogen circulation system of J-PARC high intensity neutron source since 2015. During cause investigation of performance degradation of helium refrigerator, we found out that accumulated oil like coating film on top surface of felt, which was used to hold the active charcoal in adsorber, might cause pressure difference in adsorber. We performed cold nitrogen gas flow test in the felt accumulated oil and found out that frozen oil under cold nitrogen flow caused the pressure difference.
Aso, Tomokazu; Teshigawara, Makoto; Muto, Hideki*; Aoyagi, Katsuhiro*; Takada, Hiroshi
no journal, ,
Liquid hydrogen (20 K, 1.4 MPaG) is employed as a cold neutron moderator material at the 1 MW spallation neutron source of Japan Proton Accelerator Research Complex (J-PARC). The cryogenic hydrogen system, combined with a helium refrigerator, was adopted to generate a liquid hydrogen circulation flow (185 g/s). Since January 2015, a pressure drop gradually increased between heat exchangers HXs) and an adsorber (ADS) in the helium refrigerator for each operation, causing the refrigerator performance degradation. The performance of helium refrigerator could be recovered as a result of countermeasures focused on accumulated oil removal, such as cleaning the inside HXs and exchanging the ADS at 2016 summer shutdown, however the detailed cause is still in doubt. On the other hand, a long run stable operation could be secured over 175 days in 2018. Just end of long run operation, a first high-intensity-beam injection with 1MW beam power was also carried out for one hour aiming to confirm the refrigerator performance according to design requirement.
Nakamura, Takemi; Tokunaga, Sho; Kikuchi, Masanobu
no journal, ,
Research reactor JRR-3 on Japan Atomic Energy Agency plans to replace the cold neutron source moderator vessel. Conceptual design for high-performance moderator vessel was carried out for the purpose of increasing the cold neutron source. Since the optimum geometry of the moderator vessel was determined by the nuclear characteristic analysis, its characteristics are reported.
Tokunaga, Sho; Nakamura, Takemi; Kikuchi, Masanobu
no journal, ,
Research reactor JRR-3 on Japan Atomic Energy Agency plans to replace the cold neutron source moderator vessel. Conceptual design for high-performance moderator vessel was carried out for the purpose of increasing the cold neutron source. The optimum geometry determined by the nuclear characteristic analysis was evaluated by flow analysis. Its characteristics are reported.
