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Journal Articles

High temperature gas-cooled reactors

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$$^{circ}$$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.

Journal Articles

A Prospect of development and use of the virtual tour of the physical protection exercise field

Nakagawa, Yosuke; Sukegawa, Hidetoshi; Naoi, Yosuke; Inoue, Naoko; Noro, Naoko; Okuda, Masahiro

Dai-41-Kai Nihon Kaku Busshitsu Kanri Gakkai Nenji Taikai Kaigi Rombunshu (Internet), 4 Pages, 2020/11

The physical protection exercise field, a facility equipped with various types of equipment such as sensors, cameras and fences that are used at nuclear facilities, is an effective tool for training on nuclear security at ISCN/JAEA, if it is carried out in-person. Due to the COVID-19 pandemic, the virtual tour of the facility is developed for the online training courses so that they could be more effective. The article explains the initial development of the virtual tour with some improvement inspired by using it on some occasions as well as a prospect of effective use of the virtual tour based on its characteristics.

Journal Articles

Refresh project of virtual reality system for education and training

Numata, Masaaki; Ogura, Yuichi*; Nakagawa, Yosuke; Inoue, Naoko

Dai-41-Kai Nihon Kaku Busshitsu Kanri Gakkai Nenji Taikai Kaigi Rombunshu (Internet), 3 Pages, 2020/11

JAEA/ISCN is actively using a virtual reality (VR) system for training in nuclear non-proliferation safeguards and nuclear security. The VR system allows participants to experience the environment of a nuclear power plant and a research reactor in a cyber space. It is beneficial for the participants who have never been in a nuclear power plant to see how they are even virtually, in order to learn their physical protection system. Workstations of OS for VR use Windows7 and the warrantee protection period expired in March 2020. For that reason, it was decided to renew those workstations over 2019-2020. This paper will describe its planning called "Refresh Project", which aims to minimize impacts on training and visitors, as well as first year achievement.

Journal Articles

Investigation of countermeasure against local temperature rise in vessel cooling system in loss of core cooling test without nuclear heating

Ono, Masato; Shimizu, Atsushi; Kondo, Makoto; Shimazaki, Yosuke; Shinohara, Masanori; Tochio, Daisuke; Iigaki, Kazuhiko; Nakagawa, Shigeaki; Takada, Shoji; Sawa, Kazuhiro

Journal of Nuclear Engineering and Radiation Science, 2(4), p.044502_1 - 044502_4, 2016/10

In the loss of forced core cooling test using High Temperature engineering Test Reactor (HTTR), the forced cooling of reactor core is stopped without inserting control rods into the core and cooling by Vessel Cooling System (VCS) to verify safety evaluation codes to investigate the inherent safety of HTGR be secured by natural phenomena to make it possible to design a severe accident free reactor. The VCS passively removes the retained residual heat and the decay heat from the core via the reactor pressure vessel by natural convection and thermal radiation. In the test, the local temperature was supposed to exceed the limit from the viewpoint of long-term use at the uncovered water cooling tube by thermal reflectors in the VCS, although the safety of reactor is kept. Through a cold test, which was carried out by non-nuclear heat input from gas circulators with stopping water flow in the VCS, the local higher temperature position was specified although the temperature was sufficiently lower than the maximum allowable working temperature, and natural circulation of water had insufficient cooling effect on the temperature of water cooling tube below 1$$^{circ}$$C. Then, a new safe and secured procedure for the loss of forced core cooling test was established, which will be carried out soon after the restart of HTTR.

Journal Articles

Investigation of characteristics of natural circulation of water in vessel cooling system in loss of core cooling test without nuclear heating

Takada, Shoji; Shimizu, Atsushi; Kondo, Makoto; Shimazaki, Yosuke; Shinohara, Masanori; Seki, Tomokazu; Tochio, Daisuke; Iigaki, Kazuhiko; Nakagawa, Shigeaki; Sawa, Kazuhiro

Proceedings of 23rd International Conference on Nuclear Engineering (ICONE-23) (DVD-ROM), 5 Pages, 2015/05

In the loss of forced core cooling test using High Temperature engineering Test Reactor (HTTR), the forced cooling of reactor core is stopped without inserting control rods into the core and cooling by Vessel Cooling System (VCS) to demonstrate the inherent safety of HTGR be secured by natural phenomena to make it possible to design a severe accident free reactor. In the test, the local temperature was supposed to exceed the limit from the viewpoint of long-term use at the uncovered water cooling tube by thermal reflectors in the VCS, although the safety of reactor is kept. The local higher temperature position was specified although the temperature was sufficiently lower than the maximum allowable working temperature, and natural circulation of water had insufficient cooling effect on the temperature of water cooling tube below 1$$^{circ}$$C. Then, a new safe and secured procedure for the loss of forced core cooling test was established, which will be carried out soon after the restart of HTTR.

JAEA Reports

Reconfirmation of facilities/instruments integrity by cold test of HTTR

Ono, Masato; Shinohara, Masanori; Iigaki, Kazuhiko; Tochio, Daisuke; Nakagawa, Shigeaki; Shimazaki, Yosuke

JAEA-Technology 2013-042, 45 Pages, 2014/01

JAEA-Technology-2013-042.pdf:10.51MB

In HTTR, it has passed about two years since the last performance confirmation test. During two years, the integrity of active equipment, leakage efficiency of coolant pressure boundary of piping and vessel and control system performance due to influence of damage and deterioration by earthquake and aging were not confirmed. To confirm them, the cold test by using HTTR was conducted and the system performances such as above mentioned items were evaluated by comparing with the plant data obtained by the past cold test. In the result, no abnormity was found in all the data in the cooling system of HTTR, and it was confirmed that the integrity of facilities and instruments of HTTR was maintained in good condition.

JAEA Reports

Pre-investigation of thermal load fluctuation test of the heat utilization system using the HTTR, 2

Tochio, Daisuke; Saito, Kenji; Shimazaki, Yosuke; Nakagawa, Shigeaki

JAEA-Technology 2011-033, 43 Pages, 2012/02

JAEA-Technology-2011-033.pdf:16.44MB

Thermal load fluctuation test of the heat utilization system using the HTTR are planned in order to demonstrate the reactor system stability in the case of thermal load fluctuation of the heat utilization system in the HTGR hydrogen production system. In the previous report, the investigation on the ACL fan stopping tests were conducted, and it was confirmed that the tests can be conducted under several conditions and provide the data needed to verify the plant dynamics simulation code for future HTGR. In this report, the investigations on the ACL pressurized water flow rate fluctuation tests were conducted. As the result, it is confirmed that the ACL pressurized water flow rate fluctuation tests can be conducted under several conditions and provide the data needed to verify the plant dynamics simulation code for future HTGR.

JAEA Reports

Pre-investigation of thermal load fluctuation test of the heat utilization system using the HTTR

Tochio, Daisuke; Saito, Kenji; Shimazaki, Yosuke; Nakagawa, Shigeaki

JAEA-Technology 2011-018, 43 Pages, 2011/06

JAEA-Technology-2011-018.pdf:2.44MB

In the HTTR, safety demonstration tests are performed after the first criticality achieved in 1998. Thermal load fluctuation test of the heat utilization system using the HTTR are planned in order to demonstrate reactor system stability in the case of thermal load fluctuation of the heat utilization system in HTGR hydrogen production system. So pre-investigations of thermal-load fluctuation tests using the HTTR are conducted to investigate the available test condition. As the result, it is confirmed that the ACL fan stopping tests can be conducted under a condition and provide the data needed to verify the plant dynamics simulation code for future HTGR.

Journal Articles

Pulse radiolysis study on free radical scavenger edaravone (3-methyl-1-phenyl-2-pyrazolin-5-one), 2; A Comparative study on edaravone derivatives

Hata, Kuniki; Lin, M.; Katsumura, Yosuke*; Muroya, Yusa*; Fu, H. Y.*; Yamashita, Shinichi; Nakagawa, Hidehiko*

Journal of Radiation Research, 52(1), p.15 - 23, 2011/01

 Times Cited Count:24 Percentile:63.19(Biology)

JAEA Reports

Preliminary study on HTTR tests for development of commercial HTGRs

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.

Journal Articles

Measurements of neutron capture cross section of $$^{237}$$Np for fast neutrons

Harada, Hideo; Nakamura, Shoji; Hatsukawa, Yuichi; Toh, Yosuke; Kimura, Atsushi; Ishiwatari, Yuki*; Yasumi, Atsushi*; Mabuchi, Yukio*; Nakagawa, Tsutomu*; Okamura, Kazuo*; et al.

Journal of Nuclear Science and Technology, 46(5), p.460 - 468, 2009/05

 Times Cited Count:4 Percentile:29.39(Nuclear Science & Technology)

The neutron capture cross section of $$^{237}$$Np has been measured for fast neutrons supplied at the center of the core in the Yayoi reactor. The activation method was used for the measurement, in which the amount of the product $$^{238}$$Np was determined by $$gamma$$-ray spectroscopy using a Ge detector. The representative neutron energy and the corresponding capture cross section of $$^{237}$$Np in the experiment were analytically deduced as 0.80 $$pm$$ 0.04 b at 0.214 $$pm$$ 0.009 MeV from the measured reaction rate by combining the energy dependence of the cross section in the nuclear data library ENDF/VII.0. The deduced cross section of $$^{237}$$Np at the representative neutron energy agrees with the evaluated data of ENDF/B-VII.0, but shows 15% larger value than that of JENDL-3.3 and 13% larger value than that of JENDL/AC-2008.

Journal Articles

Pulse radiolysis study on free radical scavenger edaravone (3-methyl-1-phenyl-2-pyrazolin-5-one)

Lin, M.; Katsumura, Yosuke; Hata, Kuniki; Muroya, Yusa*; Nakagawa, Keiichi*

Journal of Photochemistry and Photobiology B; Biology, 89(1), p.36 - 43, 2007/11

 Times Cited Count:28 Percentile:56.26(Biochemistry & Molecular Biology)

Journal Articles

Free radical scavenger edaravone suppresses X-ray-induced apoptosis through p53 inhibition in MOLT-4 cells

Sasano, Nakashi*; Enomoto, Atsushi*; Hosoi, Yoshio*; Katsumura, Yosuke; Matsumoto, Yoshihisa*; Shiraishi, Kenshiro*; Miyagawa, Kiyoshi*; Igaki, Hiroshi*; Nakagawa, Keiichi*

Journal of Radiation Research, 48(6), p.495 - 503, 2007/11

 Times Cited Count:22 Percentile:52.73(Biology)

Oral presentation

Study on fast-neutron capture cross section by an activation method

Nakamura, Shoji; Toh, Yosuke; Kimura, Atsushi; Hatsukawa, Yuichi; Harada, Hideo; Ishiwatari, Yuki*; Saito, Isao*; Yasumi, Atsushi*; Mabuchi, Yukio*; Nakagawa, Tsutomu*; et al.

no journal, , 

no abstracts in English

Oral presentation

Measurement of fast-neutron capture cross-section of $$^{129}$$I

Nakamura, Shoji; Toh, Yosuke; Hatsukawa, Yuichi; Kimura, Atsushi; Harada, Hideo; Yasumi, Atsushi*; Nakagawa, Tsutomu*; Mabuchi, Yukio*; Saito, Isao*; Ishiwatari, Yuki*

no journal, , 

The fast-neutron capture cross section of $$^{129}$$I was measured at the YAYOI reactor by the activation method. The amount of $$^{130}$$I was obtained by measuring $$gamma$$-rays emitted from $$^{130}$$I. The neutron flux was monitored by a piece of gold foil. The fast-neutron capture cross section was derived from the information of the production amount of $$^{130}$$I and the neutron flux. This work found that the evaluated data might be overestimated by about 10% and more.

Oral presentation

A Pulse radiolysis study on the radical scavenging reaction mechanisms of antioxidants

Hata, Kuniki; Fu, H. Y.*; Katsumura, Yosuke*; Lin, M.; Muroya, Yusa*; Yamashita, Shinichi; Kudo, Hisaaki*; Nakagawa, Hidehiko*

no journal, , 

no abstracts in English

Oral presentation

A Study on the reactivity of Edaravone with oxidative radicals by pulse radiolysis

Hata, Kuniki; Katsumura, Yosuke; Lin, M.; Muroya, Yusa*; Kudo, Hisaaki*; Nakagawa, Keiichi*; Nakagawa, Hidehiko*

no journal, , 

Edaravone, 3-methyl-1-phenyl-2-pyrazolin-5-one, is a newly developed free radical scavenger that has been approved in Japan as a neuroprotective drug since 2001. In the present work, the transient intermediates and the reactivity of edaravone towards $$^{.}$$OH, N$$_{3}$$$$^{.}$$, Br$$_{2}$$$$^{.-}$$, SO$$_{4}$$$$^{.-}$$, and CCl$$_{3}$$O$$_{2}$$$$^{.}$$ are investigated by pulse radiolysis techniques. The oxidation of edaravone by N$$_{3}$$$$^{.}$$, Br$$_{2}$$$$^{.-}$$, SO$$_{4}$$$$^{.-}$$, and CCl$$_{3}$$O$$_{2}$$$$^{.}$$ results in an absorption band with $$lambda$$$$_{max}$$ = 345 nm ($$varepsilon$$$$_{345nm}$$ = 2600 M$$^{-1}$$cm$$^{-1}$$), which is assigned to the edaravone radical formed by H-abstraction or electron transfer. However, the transient species produced by the reaction of edaravone with $$^{.}$$OH radical shows an absorption band with $$lambda$$$$_{max}$$ = 320 nm ($$varepsilon$$$$_{320nm}$$ = 4900 M$$^{-1}$$cm$$^{-1}$$). Accordingly, the main transient species by the reaction of edaravone with $$^{.}$$OH radical in the absence of O$$_{2}$$ is attributed to OH-adducts. The rate constants of edaravone reacting with $$^{.}$$OH, N$$_{3}$$$$^{.}$$, SO$$_{4}$$$$^{.-}$$, and CCl$$_{3}$$O$$_{2}$$$$^{.}$$ are estimated to be 8.5$$times$$10$$^{9}$$, 5.4$$times$$10$$^{9}$$, 6.0$$times$$10$$^{8}$$, and 5.1$$times$$10$$^{8}$$ M$$^{-1}$$s$$^{-1}$$, respectively.

Oral presentation

A Comparative study on the free radical scavenging reactivity of edaravone and its derivatives

Hata, Kuniki; Katsumura, Yosuke; Lin, M.; Muroya, Yusa*; Fu, H.*; Yamashita, Shinichi; Kudo, Hisaaki*; Nakagawa, Keiichi*; Nakagawa, Hidehiko*

no journal, , 

Edaravone (3-methyl-1-phenyl-2-pyrazolin-5-one), which is clinically used for brain infarct in Japan from 2001, is a potent antioxidative medicine. Edaravone is also expected as a radioprotector for its high reactivity towards oxidizing radicals. Recently, some edaravone derivatives have been being investigated in order to study the Structure Activity Relationship (SAR) and to seek for more efficient radioprotector(s) other than edaravone. It was reported that a derivative with a pyridine ring as a substitute had much higher reactivity with hydroxyl radical than edaravone. However, the early processes of the reactions of edaravone derivatives are not fully understood and the quantitative data about their reaction rate have not been determined. In this study we investigated the reactions between some edaravone derivatives and hydroxyl radical and determined the rate constants of these reactions by pulse radiolysis technique. The rate constants were measured by three different methods. The first was direct measurement from the buildup kinetics of transient radicals. The second was competition method using carbonate ion as a competitor. The third was competitive measurement using DMPO, which is widely used spin-trapping agent for hydroxyl radical or hydrogen atom. The experimental results showed high reactivity of all derivatives investigated in this study. These reactions are near diffusion controlled. Moreover, the rate constants of derivatives with a pyridine ring by competition with DMPO were estimated twice as high as that by direct measurement. A possible interaction between the pyridine ring and DMPO is proposed.

Oral presentation

A Study on the reaction mechanisms of edaravone and its derivatives

Hata, Kuniki; Katsumura, Yosuke; Lin, M.; Muroya, Yusa*; Yamashita, Shinichi; Fu, H. Y.*; Kudo, Hisaaki*; Nakagawa, Keiichi*; Nakagawa, Hidehiko*

no journal, , 

In order to investigate the reaction mechanism of edaravone (3-methyl-1-phenyl-2-pyrazolin- 5-one) with OH, the reactivity of edaravone derivatives which have different substituent from edaravone was observed by pulse radiolysis system. From the experiments, OH-adduct radical formed by the addition of OH to phenyl group has been identified as a main intermediate.

Oral presentation

A Study on the free radical scavenging mechanism of edaravone

Hata, Kuniki; Katsumura, Yosuke; Lin, M.; Muroya, Yusa*; Fu, H.*; Yamashita, Shinichi; Kudo, Hisaaki*; Nakagawa, Keiichi*; Nakagawa, Hidehiko*

no journal, , 

Edaravone or RadiCut, 3-methyl-1-phenyl-2-pyrazolin-5-one, is a developed free radical scavenger that has been approved in Japan as a neuroprotective drug since 2001. For its antioxidative property and high reactivity with free radicals, edaravone has been expected as a radioprotector. In the last decade, the reactivity of edaravone with peroxyl radicals or some enzymes which induce oxidizing reactions, as well as the antioxidative properties of edaravone, have been extensively investigated. However, there are only a few reports on the measurements of the reactivity of edaravone towrads OH radical, although OH radical is thought to be a main factor of indirect radiation induced damages. In this work, we measured the reactivity of edaravone with OH radical, and elucidated its reaction mechanism. The reactions of edaravone and its model compound (1,3-dimethyl-2-pyrazolin-5-one) with OH radical or other oxidizing radicals were measured by pulse radiolysis techniques. The result shows that the intermediate radical produced by the reaction of edaravone with OH radical was spectroscopically different from that by the reactions with other radicals. On the other hand, for 1,3-dimethyl-2-pyrazolin-5-one, the intermediate radical by the reaction with OH radical is similar to that by the reaction with other oxidizing radical. All these strongly suggest that the phenyl group of edaravone plays an important role on the reaction with OH radical. Thus, in contrast to the previous reports in which the oxidation by OH radical was assumed to be through electron transfer or hydrogen abstraction from pyrazolin-5-one, the formation of OH adducts is crucial for the reaction of edaravone towards OH radical.

44 (Records 1-20 displayed on this page)