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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：50.96(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.
Jo, Takahisa; Goto, Takehiro; Yabuki, Kentaro; Ikegami, Kazunori; Miyagawa, Takayuki; Mori, Tetsuya; Kubo, Atsuhiko; Kitano, Akihiro; Nakagawa, Hiroki; Kawamura, Yoshiaki; et al.
JAEA-Technology 2010-052, 84 Pages, 2011/03
JAEA-Technology-2010-052.pdf:17.14MB
The prototype fast breeder reactor MONJU resumed the System Startup Test (SST) on May 6th 2010 after five months and fourteen years shutdown since the sodium leakage of the secondary heat transport system on December 1995. Core Confirmation Test (CCT) is the first step of SST, which consists of three steps. CCT was finished on July 22nd after 78 days tests. CCT is composed 20 test items including control rods' worth evaluation, radiation dose measurement etc..
Goto, Minoru; Takamatsu, Kuniyoshi; Nakagawa, Shigeaki; Ueta, Shohei; Hamamoto, Shimpei; Ohashi, Hirofumi; Furusawa, Takayuki; Saito, Kenji; Shimazaki, Yosuke; Nishihara, Tetsuo
JAEA-Technology 2009-053, 48 Pages, 2009/10
JAEA-Technology-2009-053.pdf:3.41MB
Preliminary studies on the HTTR (High Temperature engineering Test Reactor) tests were conducted to obtain characteristics and demonstration data which were required to develop commercial HTGRs (high temperature gas-cooled reactors). The tests proposed in this study are as follows: nuclear heat supply characteristics tests, burned core tests, reactivity insertion tests, safety demonstration tests, fuel characteristics tests, annular core tests, fuel failure tests, tritium measurement tests, and health confirmation tests of high temperature equipments. Requirements for a development of commercial HTGRs and confirmation methods of the requirements by the HTTR tests were summarized. Preliminary analyses were performed for the burned core test and the safety demonstration test to obtain prediction data, which is compared with experimental data. Additionally, a feasibility analysis was performed on four types annular cores, which is composed of the HTTR's fresh fuels, from the point of view of shutdown margin and excess reactivity.
Hiura, Nobuo*; Yamaura, Takayuki; Motohashi, Yoshinobu*; Kobiyama, Mamoru*
Nihon Genshiryoku Gakkai Wabun Rombunshi, 1(2), p.202 - 208, 2002/06
The purpose of this study is to develop oxygen sensor which can measure the oxygen potential of the fuel in a nuclear reactor. The oxygen sensor with CaO stabilized zirconia solid electrolyte has been specially designed in order to prolong its life time. Electromotive force (EMF) of solid galvanic cell Ni/NiO|ZrO
-CaO|Fe/FeO was measured in both the out-pile tests and the in-situ tests using Japan Material Testing Reactor (JMTR), and the characteristics of EMF was discussed. In the out-pile test, it was found that the EMF was almost equal to the theoretical values at temperatures ranging from 700 to 1,000
, and the life span of the sensor was very long up to 980h at 800. In the in-situ test, it was found that the EMF showed almost the reliable values up to 300 h (neutron fluence (E 
1 MeV) 1.5
10
m
), at temperatures from 700 to 900. The imprecision of the EMF was found to be within 6% of the theoretical values up to 1,650 h irradiation time (neutron fluence (E 1 MeV) 8.010 m) at 800. The oxygen sensors were found to be applicable for the oxygen potential measurement of the fuels in a reactor.
Sudo, Yukio; Hoshiya, Taiji; Ishihara, Masahiro; Shibata, Taiju; Ishino, Shiori*; Terai, Takayuki*; Oku, Tatsuo*; Motohashi, Yoshinobu*; Tagawa, Seiichi*; Katsumura, Yosuke*; et al.
Proceedings of OECD/NEA 2nd Information Exchange Meeting on Basic Studies in the Field of High-temperature Engineering, p.39 - 50, 2001/00
no abstracts in English
Ishino, Shiori*; Terai, Takayuki*; Oku, Tatsuo*; Arai, Taketoshi; Hayashi, Kimio; Ito, Hisayoshi; Yano, Toyohiko*; Motohashi, Yoshinobu*; *; *; et al.
JAERI-Review 99-019, 238 Pages, 1999/08
JAERI-Review-99-019.pdf:14.88MB
no abstracts in English
*; Endo, Yasuichi; Yamaura, Takayuki; Matsui, Yoshinori; Niimi, Motoji; Hoshiya, Taiji; Kobiyama, M.*; Motohashi, Yoshinobu*
JAERI-Conf 99-006, p.343 - 348, 1999/08
no abstracts in English
Ohashi, Yusuke; Nakatsuka, Yoshiaki; Kawatsuma, Shinji; Hata, Haruhi; Tsunashima, Yasumichi; Murata, Masato; Tokizawa, Takayuki; Sugitsue, Noritake
no journal, ,
Sludge waste derived from research and discussion for uranium refining and conversion exclude much uranium. We must recover uranium from them from the point of view of use of resource and we dispose of residue generated by the process. We recovered uranium from real waste by water or hydrochloric acid. The dissolution rates of uranium from sludge from neutralization and NaF, filter medium, alumina, MgF wastes were more than 99% by 2 hour 1N HCl treatment. The dissolution rate of uranium from bed material waste was more than 99% by 24h 1N HCl treatment and addition of hydrogen peroxide. The dissolution rates of NaF, filter medium waste by water treatment were 99% and 88%. From the results, we confirmed dissolution characteristics of real waste as basic data to study recovery process of uranium.
Tsunashima, Yasumichi; Nakatsuka, Yoshiaki; Kawatsuma, Shinji; Ohashi, Yusuke; Murata, Masato; Tokizawa, Takayuki; Sugitsue, Noritake; Hata, Haruhi
no journal, ,
The operation waste generated from the uranium handling facilities of the uranium conversion and uranium enrichment, etc. is called a sludge. They are assumed to be execution of the uranium collection if necessary, cement solidification, and disposal. Therefore, the examination that confirmed the range where cement solidifies was executed. The cement kind, the water cement ratio, and the sludge mixture rate were assumed to be a parameter and the solidification test was executed. The range of solidification was confirmed by the bleeding water after 24 hours had passed. The uniaxial compression was measured with cement in the solidification condition. A possibility miscible from 40wt% to about 60wt% was able to be confirmed from these examination results in the absorbent (NaF pellet and active alumina), the bed materials (no active alumina), Neutralizing precipitation.
Yoneda, Yasuhiro; Ohashi, Takayuki*; Aoyagi, Rintaro*
no journal, ,
NaNbO is a 
O perovskite ferroelectric materials and has antiferroelectric orthorhombic structure at room temperature. Li-substituted NaNbO crystals show different phase transition sequence though have the same average structure. The purpose of this work was to clarify the local structures of Li-substituted NaNbO and to elucidate the mechanism of the ferroelectric phase transitions. A local structure analysis was carried out using the X-ray pair-distribution function (PDF) obtained from high-energy synchrotron X-ray diffraction. A clear difference in the local structures of Li-substituted NaNbO was found. The difference in the ferroelectric phase transition can be explained by the local environment around the 
-site atoms.
Mori, Tetsuya; Takano, Kazuya; Kitano, Akihiro; Morohashi, Yuko; Kato, Yuko; Yabuki, Kentaro; Miyagawa, Takayuki; Okawachi, Yasushi; Hazama, Taira
no journal, ,
Monju restarted safely on May 6, 2010 after 14 years and 5 months suspension. Core Confirmation Test was performed until July 22. The core fuel contains Am-241 because Pu-241 (half-life 14 years) decayed during 14.4 years suspension. Therefore, physics data of the core containing Am-241 are obtained. The mainly test items are criticality, control rod worth and isothermal temperature coefficient. In the criticality, the measured CR position at the criticality was confirmed to be within the predicted CR position range. Criticality was predicted in good accuracy. In the control rod worth measurement, CR worth of CCR1 was measured by the period method. CR worth of other CR was measured by the balancing method. In the isothermal temperature coefficient measurement, the measured value was a little bit smaller than that of the previous test due to the accumulation of Am-241, the decay of Pu-241, and other composition change by refuelling.
Sakazume, Yoshinori; Tokizawa, Takayuki; Noguchi, Shinichi; Kawase, Keiichi; Motohashi, Jun; Watanabe, Masanori
no journal, ,
no abstracts in English
Kijima, Yuichi; Yamamoto, Yoichi; Motohashi, Masashi*; Otsu, Takayuki*
no journal, ,
The CTBT National Operation System of Japan (NOSJ) consists of two NDCs, NDC-1 (Japan Weather Association; JWA) in charge of analysis of SHI data and NDC-2 (Japan Atomic Energy Agency; JAEA) in charge of analysis of RN data and ATM, and the Center for the Promotion of Disarmament and Non-Proliferation (CPDNP) which is the secretariat of NOSJ. The NDCs participated in the NDC preparedness exercise 2015 (NPE 2015). At first, NDC-2 made analysis of artificial (simulated) and real RN data for identification and quantification of RN, and ATM analysis for estimation of the possible source region. Then NDC-1 made analysis of seismic waveform to identify the epicenter using the result of NDC-2. Both NDCs tried to get a final conclusion collaboratively.
