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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.
Aso, Tomokazu; Kaminaga, Masanori; Hino, Ryutaro; Monde, Masanori*
Proceedings of 11th International Conference on Nuclear Engineering (ICONE-11) (CD-ROM), 8 Pages, 2003/04
no abstracts in English
Aso, Tomokazu; Kaminaga, Masanori; Haga, Katsuhiro; Kinoshita, Hidetaka; Takahashi, Toshio*; Hino, Ryutaro
JAERI-Tech 2002-096, 76 Pages, 2002/12
The JAERI and the High Energy Accelerator Research Organization have been developing a Mega-Watt scale spallation target system. In the system, neutrons generated in a target are sorted out their energy to the proper values in liquid-hydrogen moderators. Then, the liquid-hydrogen is forced to circulate in order to suppress hydrogen temperature increase. In the operation of moderators, it is very important to establish a safety protection system against emergency shutdown of the accelerator or accidents of the cold moderator system. In order to obtain a technical data for design and safety review of the liquid-hydrogen system, we have fabricated an experimental apparatus simulated the cold moderator system using liquid nitrogen (max. 1.5MPa, mini. 77K) instead of liquid hydrogen. The experiments on a controllability of the system were carried out to investigate dynamic characteristics of the system. This report presents the experimental results and technical issues for the construction of a practical liquid-hydrogen moderator system of the Mega-Watt scale target system.
Kritmaitree, P.; Akiyama, Mitsunobu*; Hino, Ryutaro; Kaminaga, Masanori; Terada, Atsuhiko*
Journal of Nuclear Science and Technology, 39(1), p.101 - 107, 2002/01
Times Cited Count：6 Percentile：39.3(Nuclear Science & Technology)The paper presents analytical results of suction process of a volumetric scroll pump, which will be developed for circulating liquid hydrogen in a cold moderator system. The multi-block grid generation approch has been applied to generate a moving boundaries computational model. The finer mesh patterns have been generated in the near-wall regions. The analysis has been carried out under liquid hydrogen flow conditions. The analytical results show that at the end of suction process the relative pressures increase significantly in a pocket while decrease continuously in another pocket. This phenomenon might damage scroll pump components if the high-pressure side is too high and/or the low-pressure side is too low until the cavitations occur. Therefore, the pockect should open to the discharge chamber before it closes and separates from the suction chamber in order to prevent the cavitations and extremely high-pressure regions.
J.Phys.,C, 20, p.753 - 763, 1987/00
no abstracts in English
Chihara, Junzo
Strongly Coupled Plasma Physics, p.587 - 596, 1987/00
no abstracts in English
; ; J.R.Bartlit*; R.H.Sherman*
Fusion Technology, 10, p.137 - 148, 1986/00
no abstracts in English
J.Phys.,C, 19, p.1665 - 1677, 1986/00
no abstracts in English
Pb
Katsuta, Hiroji; *;
Journal of Nuclear Materials, 133-134, p.167 - 170, 1985/00
Times Cited Count：28 Percentile：92.86(Materials Science, Multidisciplinary)no abstracts in English
Progress of Theoretical Physics, 72(5), p.940 - 955, 1984/00
Times Cited Count：31 Percentile：85.44(Physics, Multidisciplinary)no abstracts in English
*; Katsuta, Hiroji; Furukawa, Kazuo; *
Journal of Nuclear Materials, 97(1-2), p.59 - 66, 1981/00
Times Cited Count：9 Percentile：73.22(Materials Science, Multidisciplinary)no abstracts in English
Katsuta, Hiroji; *; Furukawa, Kazuo
Nuclear Technology, 32(3), p.297 - 303, 1977/03
Times Cited Count：35no abstracts in English
Katsuta, Hiroji; Furukawa, Kazuo
Nuclear Technology, 31(2), p.218 - 231, 1976/02
Times Cited Count：11no abstracts in English
Takada, Hiroshi
no journal, ,
At the Japan Proton Accelerator Research Complex, a pulsed spallation neutron source provides neutrons with high-intensity and narrow pulse width to promote a variety field of materials science by injecting high power proton beam of 3-GeV, 1 MW at repetition rate of 25 Hz. The core components of the spallation neutron source are a mercury target, liquid hydrogen moderators and a reflector with beryllium and iron. Their sizes and arrangement were optimized to get superior neutronics performance for 100% para-hydrogen as the moderator material. Since the lifetime of the mercury target vessel made from SS316L steel is determined by the pitting damage induced by the pressure wave generated at the pulsed proton beam injection, mitigating the pitting damage is the most critical issue to achieve 1 MW operation for long time. So far, gas micro-bubbles injection technique and a target front structure to get faster mercury flow in narrow channel were employed for mitigating the pitting damage in the mercury target vessel. A pitting damage of 25 
m was observed on the target front after 670 MWh operation with an average power of 406 kW. In 2018, it is planned to observe the target front of the newly manufactured target after operation with a power of 300 to 500 kW. Further developments of the narrow channel structure of the target front will be carried out. It is also planned to make post irradiation examination to study radiation damage of the target vessel in other facility of Japan Atomic Energy Agency.
Thwe Thwe, A.; Nagaishi, Ryuji; Furukawahara, Ryo; Ito, Tatsuya
no journal, ,
For hydrogen safety in the storage of wet radioactive materials under the decommissioning process of nuclear power stations including 1F, not only the experimental but also analytical studies on hydrogen generation from water radiolysis are important. Until now, we have conducted those closely related to the 1F decommissioning by the experiments for the effects of seawater salts, liquid depth and temperature, and by the calculations for the effect of liquid flow. In this study, we calculated the liquid-depth effect on hydrogen generation by using a one-dimensional reaction model in the vertical direction based on the open-source software CANTERA. The division of reaction cells was found to be important. As the division number increased, the slope of the increase in the amount of hydrogen generated with respect to the absorbed dose became smaller, approaching to the experimental results. However, when the number exceeded 100, the calculation results were underestimated under the current experimental and calculation conditions.
Tokunaga, Sho; Nakamura, Takemi; Kikuchi, Masanobu; Noguchi, Hironori*; Oda, Yasushi*
no journal, ,
In order to examine a hydrogen flow analysis method for the high-performance moderator vessel including the entire CNS system, a pipe network analysis of the entire system including the moderator vessel using RELAP5/MOD3.2 and a CFD analysis of the moderator vessel using ANSYS-FLUENT which added physical models that were not considered in a conceptual design were evaluated in combination. The validity of these calculations was compared using Sudo's equation, which is in good agreement with the results of the out-of-reactor operating test in the current canteen bottle moderator vessel.
