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Otokawa, Yoshinori; Matsuda, Makoto; Abe, Shinichi
JAEA-Technology 2022-037, 23 Pages, 2023/03
JAEA-Technology-2022-037.pdf:5.38MB
Bearing units of rotating shaft system for power generation in the JAEA-Tokai Tandem accelerator had a short operating life from the beginning of the accelerator installation, and even after replacing the bearing unit, early failures often occurred. Therefore, the quantity and frequency of replacement are large, and a lot of time is spent in regular maintenance performed by opening the accelerator pressure vessel, and solving this problem has been a long-standing concern. As a result of considering the cause of this early failure, it was considered that the load caused by parallel, angular, and axial misalignment of the upper and lower bearing units was the cause. In order to solve this problem, we have developed a bearing unit having metal disc-spring couplings in the upper and lower flanges to allow for parallel, angular, and axial misalignment of bearing units. As a result, it is now possible to allow variations in the distance between castings and parallel, angular, and axial misalignment of the upper and lower bearing units. By installing the developed new bearing unit on the rotating shaft system and making improvements while continuing to use it in actual operation, we succeeded in reducing the early failure and extending the operating life by more than double. With this development, the maintenance time has been reduced to one week by reducing the number of replacing the bearing unit. In addition, we have realized one regular maintenance that was carried out about three times a year, and as a benefit, we were able to reduce the amount of sulfur hexafluoride (SF
) gas, which is a greenhouse gas, to about 33
50% per year. We describe about development of new bearing units and these maintenance status from 2006 to 2020.
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.
Tanaka, Masaaki; Miyake, Yasuhiro*; Karakida, Yasuhisa*
Proceedings of 2nd International Conference on Maintenance Science and Technology (ICMST-Kobe 2014), p.79 - 80, 2014/11
A coupled method of fluid-structure thermal interaction simulation and thermal stress analysis has been developed through the interface program to carry out direct numerical estimation of the thermal fatigue. The prototype method was applied to the thermal mixing phenomena in T-junction Piping System.
Harada, Masahide; Teshigawara, Makoto; Kai, Tetsuya; Sakata, Hideaki*; Watanabe, Noboru; Ikeda, Yujiro
JAERI-Conf 2001-002, p.793 - 807, 2001/03
no abstracts in English
Ezaki, Tetsuro*; Jinno, Kenji*; Mitani, Yasuhiro*; *; Uchida, Masahiro; *
JNC TY8400 2000-004, 94 Pages, 2000/03
JNC-TY8400-2000-004.pdf:7.73MB
no abstracts in English
Shimizu, Michio; Iwamatsu, Shigemi; Takada, Fumiki; Sozawa, Shizuo; Kawamata, Kazuo; Oshima, Kunio; Tsuchiya, Kunihiko; Yamaura, Takayuki; Matsui, Yoshinori; Iwai, Takashi; et al.
JAERI-Tech 2000-029, p.48 - 0, 2000/03
JAERI-Tech-2000-029.pdf:9.26MB
no abstracts in English
Suzudo, Tomoaki; Tuerkcan, E.*; H.Verhoef*
Nuclear Science and Engineering, 129(2), p.203 - 208, 1998/06
Times Cited Count：0 Percentile：0.01(Nuclear Science & Technology)no abstracts in English
Asakura, Nobuyuki; *; Ikeda, Yoshitaka; Neyatani, Yuzuru; Seki, Masami
Review of Scientific Instruments, 66(12), p.5428 - 5432, 1995/12
Times Cited Count：18 Percentile：78.6(Instruments & Instrumentation)no abstracts in English
Udagawa, Akira; Sasuga, Tsuneo; Seguchi, Tadao; *; *; *; *; *; Sonoda, Katsumi*; *
JAERI-M 89-203, 20 Pages, 1989/12
no abstracts in English
*; *; *; *; *; *; *; *;
JAERI-M 83-142, 52 Pages, 1983/09
no abstracts in English
;
Journal of Nuclear Science and Technology, 18(11), p.897 - 900, 1981/11
Times Cited Count：1 Percentile：30.71(Nuclear Science & Technology)no abstracts in English
; *; Kaetsu, Isao
J.Appl.Polym.Sci., 22(2), p.487 - 496, 1978/02
Times Cited Count：5no abstracts in English
Kaetsu, Isao
Kagaku To Kogyo, 31(9), p.727 - 729, 1978/00
no abstracts in English
Tanaka, Masaaki; Hiyama, Tomoyuki; Murakami, Satoshi*; Doda, Norihiro; Ohshima, Hiroyuki
no journal, ,
In order to improve the accuracy of the numerical estimation method for the thermal transient phenomena in the sodium-cooled fast reactor has been conducted by using code coupling technology with the system analysis code for plant dynamics analysis, the multi-dimensional code for analysis of thermal-hydraulics in the plenum, and numerical estimation code of structural integrity for the local region, in viewpoint of enhancement of safety measures in sodium-cooled fast reactor. In this presentation, outline of simulation method development is introduced.
Okamoto, Kaoru*; Makino, Yasushi*; Ono, Ayako; Yoshida, Hiroyuki
no journal, ,
JAEA has developed an advanced neutronics/thermal-hydraulics coupling simulation system, in which detailed two-phase flow simulation code (TPFIT or JUPITER) is applied to part of thermal-hydraulics. Those detailed codes can predict small-scale thermal-hydraulics behavior inside sub-channels of a fuel bundle, so that measurement data with high-resolutions in time and space are required to achieve the appropriate validation of the codes. In this study, Laser Doppler Velocimetry (LDV) is applied for measurements of velocity and void fraction in air-water dispersed bubbly flows. The LDV can obtain local measurement data without any disturbance to flow field. In particular, fluorescent particles are introduced for liquid velocity measurements in order to clearly distinguish recorded signals between gas and liquid phases. The measurement method and the results will be shown in this presentation.
Ono, Ayako; Okamoto, Kaoru*; Makino, Yasushi*; Hosokawa, Shigeo*; Yoshida, Hiroyuki
no journal, ,
JAEA has been developing an advanced neutronic/thermal-hydraulics coupling simulation system. In the system, the detailed thermal-hydraulics codes JUPITER and TPFIT, which are based on an interface-capturing method, will be adopted to simulate thermal-hydraulics in a fuel bundle. The experimental data and findings relating to the two-phase flow in a fuel bundle are needed to validate JUPITER and TPFIT. In this study, we propose a new measurement method to measure the bubbly flow in a narrow channel, such as a subchannel, by combining laser-doppler velocimetry and photodiodes. The proposed measurement method is cross-checked by a conductance probe and is confirmed for its validity.
Okutomi, Toshifumi*; Teshigawara, Makoto; Harada, Masahide; Oi, Motoki; Yamaguchi, Yuji; Kuramoto, Shigeru*
no journal, ,
Silver/gold-indium-cadmium (Ag/Au-In-Cd) alloys as thermal neutron absorbers, which can realize high neutron cut-off energy by combining materials with neutron resonance absorption, have been used at the high-intense spallation neutron source in J-PARC. Recently, it has become difficult to treat materials including Cd. We again focused on boron (
B) having the 1/v absorption and expecting a high neutron cut-off energy as a new thermal neutron absorber. As helium (He) produced by the B(n,
) 
Li reaction causes embrittlement of material including B, it was considered that the use of B was difficult at the high-intense spallation neutron source. Therefore, we have proposed the concept called pre-decoupling, in which other thermal neutron absorber without the He production such as gadolinium (Gd) is combined with B in order to suppress the neutron absorption of B resulting reducing embrittlement. Based on the pre-decoupling concept, we have developed a material dispersing boron carbide (BC) and gadolinium oxide (Gd
O
) in aluminum (Al) as a base material. In this presentation, we will report tensile test results of the dispersing materials powder-sintered and the vision of the development.
