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Hamamoto, Shimpei; Shimizu, Atsushi; Inoi, Hiroyuki; Tochio, Daisuke; Homma, Fumitaka; Sawahata, Hiroaki; Sekita, Kenji; Watanabe, Shuji; Furusawa, Takayuki; Iigaki, Kazuhiko; et al.
Nuclear Engineering and Design, 388, p.111642_1 - 111642_11, 2022/03
Times Cited Count：2 Percentile：53.91(Nuclear Science & Technology)Following the Fukushima Daiichi Nuclear Power Plant accident in 2011, the Japan Atomic Energy Agency adapted High-Temperature engineering Test Reactor (HTTR) to meet the new regulatory requirements that began in December 2013. The safety and seismic classifications of the existing structures, systems, and components were discussed to reflect insights regarding High Temperature Gas-cooled Reactors (HTGRs) that were acquired through various HTTR safety tests. Structures, systems, and components that are subject to protection have been defined, and countermeasures to manage internal and external hazards that affect safety functions have been strengthened. Additionally, measures are in place to control accidents that may cause large amounts of radioactive material to be released, as a beyond design based accident. The Nuclear Regulatory Commission rigorously and appropriately reviewed this approach for compliance with the new regulatory requirements. After nine amendments, the application to modify the HTTR's installation license that was submitted in November 2014 was approved in June 2020. This response shows that facilities can reasonably be designed to meet the enhanced regulatory requirements, if they reflect the characteristics of HTGRs. We believe that we have established a reference for future development of HTGR.
Takeda, Tetsuaki*; Inagaki, Yoshiyuki; Aihara, Jun; Aoki, Takeshi; Fujiwara, Yusuke; Fukaya, Yuji; Goto, Minoru; Ho, H. Q.; Iigaki, Kazuhiko; Imai, Yoshiyuki; et al.
High Temperature Gas-Cooled Reactors; JSME Series in Thermal and Nuclear Power Generation, Vol.5, 464 Pages, 2021/02
As a general overview of the research and development of a High Temperature Gas-cooled Reactor (HTGR) in JAEA, this book describes the achievements by the High Temperature Engineering Test Reactor (HTTR) on the designs, key component technologies such as fuel, reactor internals, high temperature components, etc., and operational experience such as rise-to-power tests, high temperature operation at 950
C, safety demonstration tests, etc. In addition, based on the knowledge of the HTTR, the development of designs and component technologies such as high performance fuel, helium gas turbine and hydrogen production by IS process for commercial HTGRs are described. These results are very useful for the future development of HTGRs. This book is published as one of a series of technical books on fossil fuel and nuclear energy systems by the Power Energy Systems Division of the Japan Society of Mechanical Engineers.
Ono, Masato; Iigaki, Kazuhiko; Sawahata, Hiroaki; Shimazaki, Yosuke; Shimizu, Atsushi; Inoi, Hiroyuki; Kondo, Toshinari; Kojima, Keidai; Takada, Shoji; Sawa, Kazuhiro
Journal of Nuclear Engineering and Radiation Science, 4(2), p.020906_1 - 020906_8, 2018/04
On March 11th, 2011, the 2011 off the Pacific coast of Tohoku Earthquake of magnitude 9.0 occurred. When the great earthquake occurred, the High Temperature Engineering Test Reactor (HTTR) had been stopped under the periodic inspection and maintenance of equipment and instruments. A comprehensive integrity evaluation was carried out for the HTTR facility because the maximum seismic acceleration observed at the HTTR exceeded the maximum value of design basis earthquake. The concept of comprehensive integrity evaluation is divided into two parts. One is the "visual inspection of equipment and instruments". The other is the "seismic response analysis" for the building structure, equipment and instruments using the observed earthquake. All equipment and instruments related to operation were inspected in the basic inspection. The integrity of the facilities was confirmed by comparing the inspection results or the numerical results with their evaluation criteria. As the results of inspection of equipment and instruments associated with the seismic response analysis, it was judged that there was no problem for operation of the reactor, because there was no damage and performance deterioration. The integrity of HTTR was also supported by the several operations without reactor power in cold conditions of HTTR in 2011, 2013 and 2015. Additionally, the integrity of control rod guide blocks was also confirmed visually when three control rod guide blocks and six replaceable reflector blocks were taken out from reactor core in order to change neutron startup sources in 2015.
Ono, Masato; Fujiwara, Yusuke; Honda, Yuki; Sato, Hiroyuki; Shimazaki, Yosuke; Tochio, Daisuke; Homma, Fumitaka; Sawahata, Hiroaki; Iigaki, Kazuhiko; Takada, Shoji
Proceedings of 2017 International Congress on Advances in Nuclear Power Plants (ICAPP 2017) (CD-ROM), 5 Pages, 2017/04
Japan Atomic Energy Agency (JAEA) has carried out research and developments towards nuclear heat utilization of High Temperature Gas-cooled Reactor (HTGR) using High Temperature Engineering Test Reactor (HTTR). The nuclear heat utilization systems connected to HTGR will be designed on the basis of non-nuclear-grade standards in terms of easier entry for the chemical plant companies and the construction economics of the systems. Therefore, it is necessary that the reactor operations continue even if abnormal events occur in the systems. Heat application system abnormal simulating test with HTTR was carried out in non-nuclear heating operation to focus on the thermal effect in order to obtain data of the transient temperature behavior of the metallic components in the Intermediate Heat Exchanger (IHX). The IHX is the key components to connect the HTTR with the heat application system. In the test, the coolant helium gas temperature was heated up to 120C by the compression heat of the gas circulators in the HTTR under the ideal condition to focus on the heat transfer. The tests were conducted by decreasing the helium gas temperature stepwise by increasing the mass flow rate to the air cooler. The temperature responses of the IHX were investigated. For the components such as the heat transfer tubes and heat transfer enhancement plates of IHX, the temperature response was slower in the lower position in comparison with the higher position. The reason is considered that thermal load fluctuation is imposed in the secondary helium gas which flows from the top to the bottom in the heat transfer tubes of the IHX. The test data are useful to verify the numerical model of the safety evaluation code.
Tochio, Daisuke; Honda, Yuki; Sato, Hiroyuki; Sekita, Kenji; Homma, Fumitaka; Sawahata, Hiroaki; Takada, Shoji; Nakagawa, Shigeaki
Journal of Nuclear Science and Technology, 54(1), p.13 - 21, 2017/01
Times Cited Count：1 Percentile：10.62(Nuclear Science & Technology)GTHTR300C is designed and developed in JAEA. The reactor system is required to continue a stable and safety operation as well as a stable power supply in the case that thermal-load is fluctuated by the occurrence of abnormal event in the heat utilization system. Then, it is necessary to demonstrate that the thermal-load fluctuation should be absorbed by the reactor system so as to continue the stable and safety operation could be continued. The thermal-load fluctuation absorption tests without nuclear heating were planned and conducted in JAEA to clarify the absorption characteristic of thermal-load fluctuation mainly by the reactor and by the IHX. As the result it was revealed that the reactor has the larger absorption capacity of thermal-load fluctuation than expected one, and the IHX can be contributed to the absorption of the thermal-load fluctuation generated in the heat utilization system in the reactor system. It was confirmed from there result that the reactor and the IHX has effective absorption capacity of the thermal-load fluctuation generated in the heat utilization system. Moreover it was confirmed that the safety estimation code based on RELAP5/MOD3 can represents the thermal-load fluctuation absorption behavior conservatively.
Honda, Yuki; Tochio, Daisuke; Nakagawa, Shigeaki; Sekita, Kenji; Homma, Fumitaka; Sawahata, Hiroaki; Sato, Hiroyuki; Sakaba, Nariaki; Takada, Shoji
JAEA-Technology 2016-016, 16 Pages, 2016/08
JAEA-Technology-2016-016.pdf:2.84MB
A system analysis code is validated with the thermal-load fluctuation absorption test with nun-nuclear heating by using the High Temperature Engineering test Reactor (HTTR) to clarify the High Temperature Gas-cooled Reactor (HTGR) system response against temperature transient. The thermal-load fluctuation absorption test consists on the thermal load fluctuation tests (non-nuclear heating) and heat application system abnormal simulating test (non-nuclear heating). The HTGR reactor response against temperature transient is clarified in the thermal load fluctuation test (non-nuclear heating). The Intermediate Heat Exchanger (IHX) reactor response against temperature transient is clarified in the heat application system abnormal simulating test (non-nuclear heating). With the two HTTR non-nuclear heating test, HTGR system response against temperature transient is obtained.
Cs (TRACs) for Fukushima Nuclear Power Plant accidentNagai, Yasuki; Makii, Hiroyuki; Namiki, Shinji; Iwamoto, Osamu; Iwamoto, Nobuyuki; Sawahata, Hiroyuki*
Journal of the Physical Society of Japan, 81(8), p.085003_1 - 085003_2, 2012/08
Times Cited Count：1 Percentile：10.8(Physics, Multidisciplinary)We propose to use the radionuclide Cs as a tracer. 
-ray energy of the most intense line from the decay of Cs is 668 keV, which is very near to that of the 662 keV from the decay of 
Cs, while the half-life of Cs is 6.5 d. Cs can be produced by nuclear reactions such as 
Cs(n,2n)Cs, Cs(r,n)Cs or Xe(p,n)Cs. The Cs tracer would be useful in the quantitative studies of radionuclide Cs contaminant in human, and in any experimental studies in the minimization of radionuclide Cs contamination in agricultural and stock farming products.
-ray analysis and construction of its beam lineOshima, Masumi; Toh, Yosuke; Kimura, Atsushi; Ebihara, Mitsuru*; Oura, Yasuji*; Ito, Yasuo*; Sawahata, Hiroyuki*; Matsuo, Motoyuki*
Journal of Radioanalytical and Nuclear Chemistry, 271(2), p.317 - 321, 2007/02
Times Cited Count：11 Percentile：61.1(Chemistry, Analytical)By combining neutron activation analysis with multiple -ray detection, we have proved better sensitivity and resolution for the trace element analysis than the ordinary single -ray detection method. We now try to apply the multiple -ray detection method to the prompt -ray analysis (PGA). We have established a new cold neutron beam line for PGA in Japan Research Reactor, JRR-3M, at Tokai establishment of Japan Atomic Energy Research Institute(JAERI). It consists of a beam shutter, a beam attenuator, a -ray detector array, a sample changer, and a beam stopper. We construct a high-efficiency -ray detector array specially designed for this purpose. Its performance has been evaluated with the Monte Carlo simulation code, GEANT 4.5.0.
Hamamoto, Shimpei; Iigaki, Kazuhiko; Shimizu, Atsushi; Sawahata, Hiroaki; Kondo, Makoto; Oyama, Sunao; Kawano, Shuichi; Kobayashi, Shoichi; Kawamoto, Taiki; Suzuki, Hisashi; et al.
JAEA-Technology 2006-030, 58 Pages, 2006/03
JAEA-Technology-2006-030.pdf:10.69MB
During normal operation of High Temperature engineering Test Reactor (HTTR) in Japan Atomic Energy Agency (JAEA), the reactivity is controlled by the Control Rods (CRs) system which consists of 32 CRs (16 pairs) and 16 Control Rod Drive Mechanisms (CRDMs). The CR system is located in stand-pipes accompanied by the Reserved Shutdown System (RSS). In the unlikely event that the CRs fail to be inserted, the RSS is provided to insert B
C/C pellets into the core. The RSS shall be designed so that the reactor should be held subcriticality from any operation condition by dropping in the pellets. The RSS consists of BC/C pellets, hoppers which contain the pellets, electric plug, driving mechanisms, guide tubes and so on. In accidents when the CRs cannot be inserted, an electric plug is pulled out by a motor and the absorber pellets fall into the core by gravity. A trouble, malfunction of one RSS out of sixteen, occurred during a series of the pre-start up checks of HTTR on February 21, 2005. We investigated the cause of the RSS trouble and took countermeasures to prevent the issue. As the result of investigation, the cause of the trouble was attributed to the following reason: In the motor inside, The Oil of grease of the multiplying gear flowed down from a gap of the oil seal which has been deformed and was mixed with abrasion powder of brake disk. Therefore the adhesive mixture prevented a motor from rotating.
Sasajima, Fumio; Sawahata, Hiroyuki*; Onizawa, Koji*; Ichimura, Shigeju; Otomo, Akitoshi; Ito, Yasuo*; Takayanagi, Masaji
JAERI-Tech 2000-073, 49 Pages, 2000/12
JAERI-Tech-2000-073.pdf:4.43MB
no abstracts in English
Yonezawa, Chushiro; ; ; Hoshi, Michio; Sawahata, Hiroyuki*; Ito, Yasuo*
Proc. of 9th Int. Symp. on Capture Gamma-ray Spectroscopy and Related Topics, 0, p.705 - 712, 1997/00
no abstracts in English
Yonezawa, Chushiro; ; Sawahata, Hiroyuki*; *; Hoshi, Michio; Ito, Yasuo*
Cancer Neutron Capture Therapy, 0, p.221 - 225, 1996/00
no abstracts in English
B in BNCTYonezawa, Chushiro; ; Sawahata, Hiroyuki*; *; Hoshi, Michio; Ito, Yasuo*
KURRI-TR-413, 0, p.21 - 27, 1995/00
no abstracts in English
Furusawa, Takayuki; Homma, Fumitaka; Inoi, Hiroyuki; Sawahata, Hiroaki; Nemoto, Takahiro; Watanabe, Shuji; Ota, Yukimaru
no journal, ,
Japan Atomic Energy Agency has constructed the HTTR (High Temperature engineering Test Reactor), which is the Japan's first High Temperature Gas-cooled Reactor (HTGR). The HTTR achieved the full power of 30MW and reactor outlet coolant temperature of 950C on April 19, 2004. Based on the HTTR maintenance experiences, the preservation technology for HTGR are developed. This paper describes its preservation philosophy and typical developed technologies.
Endo, Kiyoshi*; Nakai, Kei*; Yoshida, Fumiyo*; Shirakawa, Shin*; Yamamoto, Tetsuya*; Matsumura, Akira*; Sawahata, Hiroyuki*; Kawate, Minoru*; Saito, Kimiaki; Kumada, Hiroaki; et al.
no journal, ,
no abstracts in English
Moriyama, Shinichi; Kobayashi, Takayuki; Sawahata, Masayuki; Terakado, Masayuki; Hiranai, Shinichi; Wada, Kenji; Hinata, Jun; Sato, Fumiaki; Yokokura, Kenji; Hoshino, Katsumichi; et al.
no journal, ,
Assembly of the JT-60SA and preparation of its ECH system are progressing and the first plasma is planned in 2019. The high voltage power supply for two gyrotrons will be procured by EU. The procurement arrangement was signed in July 2015. Its fabrication in EU will be done in 2016 and the installation to the Naka-site will be in 2017. Oscillations at 1 MW for 100 s as the development target of the JT-60SA gyrotron were achieved at both 110 GHz and 138 GHz in June 2014. The gyrotron is the first "1 MW multi-frequency gyrotron" reached the pulse duration of 100s at two frequencies. In addition, 82 GHz oscillation was achieved at 1.0 MW for 1 sec by this gyrotron in June 2015. This additional frequency would be applicable to plasma start-up assistance and wall conditioning at the fundamental EC resonance in JT-60SA. Development is steadily progressing on the waveguide components and the launcher.
Hirota, Koichi; Sawahata, Hiroyuki*
no journal, ,
Takasaki Advanced Radiation Research Institute has three irradiation facilities of ion-beam, -ray, and electron-beam aimed at developing cutting-edge technologies for advanced materials, environmental conservation, biotechnology, and medical application. These facilities are available for basic and applied researches by academics, national and local government institutes, and private companies under the cooperation program. For example, the cyclotron is used for researches on radiation-degradation phenomena of semiconductors for space use, controlled polymerization of nanowire, breed improvement etc. The -ray facilities contribute to diverse research themes and recent noteworthy work is development of radiation-resistant materials for the decommissioning of damaged Fukushima Daiichi Nuclear Power Plant. Users under this cooperation program have advantages of preferential utilization of machine time and utilization fee subsidization. This presentation focuses on the detail of this program with the examples of actual research results.
Moriyama, Shinichi; Kobayashi, Takayuki; Sawahata, Masayuki; Terakado, Masayuki; Hiranai, Shinichi; Wada, Kenji; Hinata, Jun; Sato, Fumiaki; Yokokura, Kenji; Hoshino, Katsumichi; et al.
no journal, ,
Assembly of the JT-60SA and preparation of its ECH system are progressing and the first plasma is planned in 2019. The high voltage power supply for two gyrotrons will be procured by EU. The procurement arrangement was signed in July 2015. Its fabrication in EU will be done in 2016 and the installation to the Naka-site will be in 2017. Oscillations at 1 MW for 100 s as the development target of the JT-60SA gyrotron were achieved at both 110 GHz and 138 GHz in June 2014. The gyrotron is the first "1 MW multi-frequency gyrotron" reached the pulse duration of 100s at two frequencies. In addition, 82 GHz oscillation was achieved at 1.0 MW for 1 sec by this gyrotron in June 2015. This additional frequency would be applicable to plasma start-up assistance and wall conditioning at the fundamental EC resonance in JT-60SA. Development is steadily progressing on the waveguide components and the launcher.
