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Nemoto, Takahiro; Arakawa, Ryoki; Kawakami, Satoru; Nagasumi, Satoru; Yokoyama, Keisuke; Watanabe, Masashi; Onishi, Takashi; Kawamoto, Taiki; Furusawa, Takayuki; Inoi, Hiroyuki; et al.
JAEA-Technology 2023-005, 33 Pages, 2023/05
JAEA-Technology-2023-005.pdf:5.25MB
During shut down of the HTTR (High Temperature engineering Test Reactor) RS-14 cycle, an increasing trend of filter differential pressure for the helium gas circulator was observed. In order to investigate this phenomenon, the blower of the primary helium purification system was disassembled and inspected. As a result, it is clear that the silicon oil mist entered into the primary coolant due to the deterioration of the charcoal filter performance. The replacement and further investigation of the filter are planning to prevent the reoccurrence of the same phenomenon in the future.
Tochio, Daisuke; Fujimoto, Nozomu
Journal of Nuclear Science and Technology, 53(3), p.425 - 431, 2016/03
Times Cited Count：1 Percentile：10.71(Nuclear Science & Technology)The future HTGR is now designed in JAEA. The reactor has many merging points of helium gas with different temperature. It is needed to clear the mixing characteristics of helium gas at the pipe in the HTGR from the viewpoint of structure integrity and temperature control. Previously, the reactor inlet coolant temperature was controlled lower than specific one in the HTTR due to lack of mixing of helium gas in the primary cooling system. Now the control system is improved to use the calculated bulk temperature of reactor inlet helium gas. In this paper, thermal-hydraulic analysis on the primary cooling system of the HTTR was conducted to clarify the mixing behavior of helium gas. As the result, it was confirmed that the mixing behavior of helium gas in the primary cooling system is mainly affected by the aspect ratio of annular flow path, and it is needed to consider the mixing characteristics of helium gas at the piping design of the HTGR.
Nakamura, Tatsuya; Tanaka, Hiroki; Yamagishi, Hideshi; Soyama, Kazuhiko; Aizawa, Kazuya; Ochi, Atsuhiko*; Tanimori, Toru*
Nuclear Instruments and Methods in Physics Research A, 573(1-2), p.187 - 190, 2007/04
Times Cited Count：9 Percentile：56.38(Instruments & Instrumentation)We have been developing a neutron imaging gas detector with a high spatial resolution and with a high temporal response for the neutron scattering instruments at the pulsed neutron source in the Japan proton accelerator research complex. The gas detector system with individual read-outs was developed to meet the requirements for the instruments for neutron reflectometry or for small angle neutron scattering. The performances of the prototype detector using a multi-wire (MW) or micro-strip (MS) detector head were evaluated using a collimated neutron beam, and we confirmed the MS detector exhibiting a spatial resolution of 1.5 mm and a pulse-pair resolution of about 100 ns with a gas pressure of 6 atm helium with a mixture of 30% CF
. The performances for the MS detector were also evaluated up to the total gas pressure of 8 atm.
Sakaba, Nariaki; Tachibana, Yukio; Nakagawa, Shigeaki; Hamamoto, Shimpei
Transactions of 18th International Conference on Structural Mechanics in Reactor Technology (SMiRT-18), p.4499 - 4511, 2005/08
Safety demonstration tests using the HTTR are now underway in order to verify the inherent safety features and to improve the safety design and evaluation technologies for HTGRs, as well as to contribute to research and development for the VHTR, which is one of the Generation IV reactor candidates. The coolant flow reduction test by running down gas circulators, which is one of the safety demonstration tests, is a simulation test of anticipated transients without scram. During the coolant flow reduction test, temperature of the high-temperature helium components and chemistry in the primary circuit are changed rapidly. This paper describes the structural integrity assessments of helium components, e.g. helium pipes, heat exchangers, during the coolant flow reduction test. From the result of this evaluation, it was found that the helium components were kept their structural integrity during temperature and chemistry transient condition in the coolant flow reduction test from the reactor power at 30%. It was also confirmed by this assessment that the coolant flow reduction test will be able to perform with its enough safety margins from the reactor power at 100%.
Kawamura, Yoshinori; Iwai, Yasunori; Nakamura, Hirofumi; Hayashi, Takumi; Yamanishi, Toshihiko; Nishi, Masataka
Fusion Science and Technology, 48(1), p.654 - 657, 2005/07
Times Cited Count：3 Percentile：24.22(Nuclear Science & Technology)Adding some amount of hydrogen to the helium sweep gas is effective for tritium extraction from blanket, but it causes permeation of tritium to a cooling system. In the design study of a demonstration reactor in JAERI, tritium leakage has been estimated to be about 20% of bred tritium under typical sweep gas conditions. If these tritiums are recovered under the ITER-WDS condition, tritium leakage limitation has to be less than 0.3% of typical case. Water vapor addition to the sweep gas is effective not only for blanket tritium extraction but also for permeation prevention. The reaction rate of isotope exchange is larger than the case of H
, and the equilibrium constant is also expected to be about 1.0. When the H/T ratio is 100, tritium inventory of breeder material is larger than the case of H addition. However it is not so large. In case of HO sweep, separation of tritiated water from helium seems to be easyer, but the process that changes HTO to HT is necessary.
Sato, Hiroyuki; Ohashi, Hirofumi; Inaba, Yoshitomo; Maeda, Yukimasa; Takeda, Tetsuaki; Nishihara, Tetsuo; Inagaki, Yoshiyuki
JAERI-Tech 2005-014, 89 Pages, 2005/03
JAERI-Tech-2005-014.pdf:7.25MB
In a hydrogen production system using HTTR, it is required to control a secondary helium gas temperature within an allowable value at an intermediate heat exchanger (IHX) inlet to prevent a reactor scram. To mitigate thermal disturbance of the secondary helium gas caused by the hydrogen production system, a cooling system of the secondary helium gas using a steam generator(SG) and a radiator will be installed at the downstream of the chemical reactor. In order to verify a numerical analysis code of the cooling system, numerical analysis has been conducted. The pressure controllability in SG is highly affected by the heat transfer characteristics of air which flows outside of the heat exchanger tube of the radiator. In order to verify a numerical analysis code of the cooling system, the heat transfer characteristics of air has been investigated with experimental results of a mock-up model test. It was confirmed that numerical analysis results were agreed well with experimental results, and the analysis code was successfully verified.
Fumizawa, Motoo; Tanaka, Gaku*; Zhao, H.*; Hishida, Makoto*; Shiina, Yasuaki
Nihon Genshiryoku Gakkai Wabun Rombunshi, 3(4), p.313 - 322, 2004/12
This paper deals with a computer simulation of a helium-air counter flow in a rectangular channel. The inclination angle is varied from 0
(horizontal) to 90(vertical). Velocity profiles and concentration profiles are calculated with a computer program VSOP sub-module. Following main features of the counter flow are discussed. (1) Time required to establish a quasi-steady state counter flow. (2) The relationship between the inclination angle and the flow patterns of the counter flow (3) The developing process of velocity profiles and concentration profiles (4) The relationship between the inclination angle of the channel and the velocity profiles of upwards flow and the downwards flow (5) The relationship between the concentration profile and the inclination angle (6) The relationship between the net in-flow rate and the inclination angle We compared the computed velocity profile and the net in-flow rate with experimental data. A good agreement is obtained between the calculation and the experiment.
Otsuki, Ryusei*; Nasu, Shoichi*; Fujimori, Ryosuke*; Anada, Kinji*; Ohashi, Kentaro*; Yamamoto, Ryoichi*; Fujii, Kimio; Okubo, Keisuke*
Funtai Oyobi Fummatsu Yakin, 51(8), p.622 - 625, 2004/08
Effects of carbon materials on weight yield of (C
+C
) and weight ratios of C to (C+C) in soot were examined by the Joule resistive heating of four kinds of carbon materials at He gas pressures from 0.7
10
8.010Pa for collector radii of 45, 50 and 55mm. The yields were in the range of 1 to 8% for graphite with hexagonal lattice, and better than those for glassy carbon. The most effective He gas pressure for the fullerene yield were in the range of 4.05.310Pa. Any collector radii dependence of the yields was not observed. The weight ratios of C to (C+C) were about 60 to 70%, and showed neither He gas pressure depenndennce nor collector radii depenndence four kinds of carbon materials.
Otsuki, Ryusei*; Nasu, Shoichi*; Ohashi, Kentaro*; Yamamoto, Ryoichi*; Fujii, Kimio; Okubo, Keisuke*
Funtai Oyobi Fummatsu Yakin, 51(8), p.626 - 629, 2004/08
The He, Ar and the Penning gas pressureeffects on the preparation yieldsof the fullerenes were investigated by means of the arc discharge method using graphite(PGX) anode buried in a tungsten rod and tungsten cathode for collector radii of 50mm. The maximum yield showed about 13-14 % at 67KPa in He gas. The yields in the mixtures of He and Ne gases (the Penning effect) were similar to those obtained in He gas. Weight ratios of C to (C+C) were about 20% in Ar gas, while those in He and Penning gas were about 60%. Ultra sonic vibration was effective to separate C from soot.
Nakamura, Tatsuya; Masaoka, Sei; Yamagishi, Hideshi; Sakasai, Kaoru; Soyama, Kazuhiko; Aizawa, Kazuya
IEEE Transactions on Nuclear Science, 51(4), p.1519 - 1523, 2004/08
Times Cited Count：2 Percentile：18.41(Engineering, Electrical & Electronic)A capillary plate (CP) comprising an assembly of fine glass tubes was applied as a pre-gas-amplification device for a microstrip gas chamber (MSGC) operating under high-gas pressure of helium-3 for use in neutron detection. The collection efficiency of the electrons between the CP and MSGC was maximally 17% using neutrons. The effective gas gain of the detector system was 600 at a gas pressure of 3 atm with a 10% mixture of ethane with helium-3, confirming the feasibility of the CP as a pre-gas-amplification device. Moreover, we demonstrated that the coincidence measurement of the signals between the CP and the anodes of MSGC decreased the background levels of electronics noise, electronic discharges, and 
-rays, indicating that a detector system with a low background can be constructed using the CP.
Furusawa, Takayuki; Sumita, Junya; Ueta, Shohei; Nemoto, Takahiro; Oyama, Sunao*; Kamata, Takashi
JAERI-Tech 2004-024, 46 Pages, 2004/03
JAERI-Tech-2004-024.pdf:6.75MB
Primary helium circulators of the HTTR are the important component as the helium gas which is reactor coolant, and three circulators for the primary pressurized water cooler and one for the intermediate heat exchanger are installed in primary cooling system. In the upstream of these circulators, the filter has been installed in order to suppress that it is entrapped in the bearing in which fine particles in helium gas, support main shaft of the helium circulator. The differential pressure of this filter rose gradually during rise-to-power test. The rise of the filter differential pressure of the helium circulator may cause the problem for reactor operation. Therefore, the filters were newly manufactured, and replacement of the filter was carried out. In replacement of the filter, appearance confirmation was carried out and deposit of the filter was analyzed. This paper described replacement of the filter and filter differential pressure rise investigation of the causes.
Kosugiyama, Shinichi; Takizuka, Takakazu; Kunitomi, Kazuhiko; Yan, X.; Katanishi, Shoji; Takada, Shoji
Nihon Genshiryoku Gakkai Wabun Rombunshi, 2(3), p.319 - 331, 2003/09
no abstracts in English
Nakamura, Tatsuya; Masaoka, Sei; Yamagishi, Hideshi; Soyama, Kazuhiko; Aizawa, Kazuya
Proceedings of ICANS-XVI, Volume 1, p.441 - 446, 2003/07
Development of a Micro-Strip Gas Chamber(MSGC) in JAERI is presented. The performances we aim at are counting rate 
10
, position resolution 
1
, detection efficiency 60% at thermal neutron and good n/gamma discrimination. Our two-dimensional gas detector consists of a micro strip plate printed on a polyimide substrate and a high pressure gas chamber which has all the signal lines are directly taken out (256ch individual readout) and withstands the pressure of 10bar 
. The individual signal readout opens the way to realize high counting rate and high position resolution at the same time. We carried out range measurements of secondary particles to confirm the range measuring power of the MSGC with that read out method. The measured ranges in the gas of 3bar helium mixed with 
ethane is 3mm, 9.5mm for triton and proton, respectively. Those values are well agreed with theoretical estimation and we could show the feasibility of the precise measurement of the ranges by the MSGC.
Masaoka, Sei; Nakamura, Tatsuya; Yamagishi, Hideshi; Soyama, Kazuhiko
JAERI-Research 2003-012, 14 Pages, 2003/06
JAERI-Research-2003-012.pdf:1.58MB
A micro-strip gas chamber (MSGC) using helium-3 gas has been developing as a two-dimensional position sensitive neutron detector for neutron scattering experiments in a high-intensity proton accelerator facility. We have developed the encode board that have built-in FPGAs (Field-Programmable Gate Array). Logics of FPGAs can be freely programmed to carry out digital processing of signals from MSGC and information of the tracks of protons and tritons can be obtained by the encode board. Therefore, the position of neutron capture (more properly the centra of the track) can be calculated by a series of data handling system. As the result of the simulation of a neutron detection experiment, it has proved that the position resolution of less than 1.6 mm can be obtained by using this data handling system.
Igarashi, Shinichi; Muto, Shunsuke*; Tanabe, Tetsuo*; Aihara, Jun; Hojo, Kiichi
Surface & Coatings Technology, 158-159, p.421 - 425, 2002/09
no abstracts in English
Ishiyama, Shintaro; Muto, Yasushi; Ogata, Hiroshi*; Kamito, Yoshimi*
Nihon Genshiryoku Gakkai-Shi, 43(7), p.708 - 717, 2001/07
Times Cited Count：3 Percentile：27.1(Nuclear Science & Technology)no abstracts in English
Inaba, Yoshitomo; Fumizawa, Motoo*; Tonogochi, Makoto*; Takenaka, Yutaka*
Applied Energy, 67(4), p.395 - 406, 2000/12
Times Cited Count：10 Percentile：50.12(Energy & Fuels)no abstracts in English
Tachibana, Yukio; Hontani, Koji*; Takeda, Takeshi; Saikusa, Akio; Shinozaki, Masayuki; Isozaki, Minoru; Iyoku, Tatsuo; Kunitomi, Kazuhiko
Nuclear Engineering and Design, 201(2-3), p.227 - 238, 2000/10
Times Cited Count：3 Percentile：26.42(Nuclear Science & Technology)no abstracts in English
Seki, Yasushi; Mori, Seiji*; Nishio, Satoshi; Ueda, Shuzo; Kurihara, Ryoichi
Journal of Nuclear Science and Technology, 37(Suppl.1), p.268 - 275, 2000/03
no abstracts in English
*; Miyamoto, Yoshiaki; Akino, Norio; Shiina, Yasuaki; Hishida, Makoto*; Ogawa, Masuro; Fumizawa, Motoo; Inagaki, Yoshiyuki; Takeda, Tetsuaki; Takada, Shoji; et al.
JAERI-Review 98-024, 403 Pages, 1999/01
JAERI-Review-98-024.pdf:17.17MB
no abstracts in English
