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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.

JAEA Reports

Applicability confirmation test of optimum decay heat evaluation method for HTGR with HTTR (Non-nuclear heating test); Validation of residual heat evaluation model

Honda, Yuki; Inaba, Yoshitomo; Nakagawa, Shigeaki; Yamazaki, Kazunori; Kobayashi, Shoichi; Aono, Tetsuya; Shibata, Taiju; Ishitsuka, Etsuo

JAEA-Technology 2017-013, 20 Pages, 2017/06

JAEA-Technology-2017-013.pdf:2.52MB

Decay heat is one of an important factor for a safety evaluation of depressurized loss-of-forced cooling accident, a representative high consequence accident, in high temperature gas-cooled reactor (HTGR). Traditionally, a conservative decay heat curve is used for safety analysis according to the regulatory standards. On the other hand, there is growing interest in obtaining test data related to decay heat for the use of uncertainty analysis. However, such data has not been obtained for prismatic-type HTGR. Therefore, we have launched a test program to obtain the decay heat data from the HTTR. As an initial step, an applicability confirmation test of decay heat evaluation method for HTGR was conducted in February 2017 without non-nuclear heating condition. This report introduces an estimation method for the decay heat based on test data using HTTR and shows the results of validation of the reactor residual heat evaluation method which will be used to obtain the decay heat data based on test data.

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

Characteristic confirmation test by using HTTR and investigation of absorbing thermal load fluctuation

Honda, Yuki; Tochio, Daisuke; Sato, Hiroyuki; Nakagawa, Shigeaki; Ono, Masato; Fujiwara, Yusuke; Hamamoto, Shimpei; Iigaki, Kazuhiko; Takada, Shoji

Proceedings of 24th International Conference on Nuclear Engineering (ICONE-24) (DVD-ROM), 5 Pages, 2016/06

The characteristic confirmation test has been demonstrating by using the High Temperature engineering Test Reactor (HTTR). The thermal load fluctuation test, which is one of marginal performance test is planned to be carried out after restarting of the HTTR. The preliminary analysis for the thermal load fluctuation test has been investigated. In the analysis, the reactor outlet temperature can continue to be stable against the reactor inlet temperature changing by thermal fluctuation. It means that HTGR have the capability of absorbing thermal fluctuation. This paper focuses on the investigation of mechanism of absorbing thermal fluctuation. With additional analysis, it is cleared that the large negative graphite moderator reactivity enhances the capability of absorbing thermal fluctuation. In addition, in the middle of the core, graphite moderator reactivity insertion trend are inverted. This trend is unique to HTGR because of large temperature difference between core inlet and outlet.

Journal Articles

Establishment of control technology of the HTTR and future test plan

Honda, Yuki; Saito, Kenji; Tochio, Daisuke; Aono, Tetsuya; Hirato, Yoji; Kozawa, Takayuki; Nakagawa, Shigeaki

Journal of Nuclear Science and Technology, 51(11-12), p.1387 - 1397, 2014/11

 Times Cited Count:1 Percentile:10.7(Nuclear Science & Technology)

The operational experiments of the HTTR would be useful for future high-temperature gas-cooled reactors (HTGRs). Main PID control constants of the HTTR are selected with reasonably damped characteristics and without undershoot or overshoot. For utilization the HTGR as a commercial reactor, it should be demonstrated that the HTGR system can supply stable heat to a heat utilization system for the long-term operation. The control characteristics in the long-term high-temperature operation are evaluated by the result of operation performed in 2010. In addition, from a viewpoint of HTGRs with heat utilization system, a future possibility of the experiments for heat utilization design is examined.

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.

Journal Articles

Integrated on-line plant monitoring system for HTTR with neural networks

Nabeshima, Kunihiko; Subekti, M.*; Matsuishi, Tomomi*; Ono, Tomio*; Kudo, Kazuhiko*; Nakagawa, Shigeaki

Journal of Power and Energy Systems (Internet), 2(1), p.92 - 103, 2008/00

The neural networks have been utilized in on-line monitoring-system of High Temperature Engineering Tested Reactor (HTTR) with thermal power of 30 MW. In this system, several neural networks can independently model the plant dynamics with different architecture, input and output signals and learning algorithm. One of main task is real-time plant monitoring by Multi-Layer Perceptron (MLP) in auto-associative mode, which can model and estimate the whole plant dynamics by training normal operational data only. Other tasks are on-line reactivity prediction, reactivity and helium leak monitoring, respectively. From the on-line monitoring results at the safety demonstration tests, each neural network shows good prediction and reliable detection performances.

Journal Articles

Integrated on-line plant monitoring system for HTTR using neural networks

Nabeshima, Kunihiko; Matsuishi, Tomomi*; Makino, Jun*; Subekti, M.*; Ono, Tomio*; Kudo, Kazuhiko*; Nakagawa, Shigeaki

Proceedings of 15th International Conference on Nuclear Engineering (ICONE-15) (CD-ROM), 6 Pages, 2007/04

The neural networks have been utilized in on-line monitoring system of High Temperature Engineering Tested Reactor (HTTR) with thermal power of 30MW. In this system, several neural networks can independently model the plant dynamics with different architecture, input and output signals and learning algorithm. One of main task is real-time plant monitoring by Multi-Layer Perceptron (MLP) in auto-associative mode, which can model and estimate the whole plant dynamics by training normal operational data only. Other tasks are on-line reactivity prediction, reactivity and helium leak monitoring, respectively. From the on-line test results, each neural network shows good prediction and reliable detection performances.

JAEA Reports

Benchmark experiments of MOX fueled LMFBR using FCA-XVII-1 core

Ando, Masaki; Iijima, Susumu*; Oigawa, Hiroyuki; Sakurai, Takeshi; Nemoto, Tatsuo*; Okajima, Shigeaki; Osugi, Toshitaka*; Ono, Akio; Hayasaka, Katsuhisa; Sodeyama, Hiroshi

JAEA-Data/Code 2006-006, 67 Pages, 2006/03

JAEA-Data-Code-2006-006.pdf:6.08MB

As a part of research and development of an advanced fueled fast reactor, we carried out benchmark experiments in the FCA-XVII-1 core with MOX simulating fuel to obtain reference data to be compared with those measured in the FCA-XVI-1 and XVI-2 cores simulating metallic fueled FBR. Following nuclear characteristics were measured in the experiments: Criticality, reaction rate ratio, sample reactivity worth, sodium void reactivity effect and $$^{238}$$U Doppler effect. Extra measurements were performed in modified FCA-XVII-1 cores to obtain experimental data for various reactor types: (1) Measurement of sodium void reactivity effect in various plutonium isotope compositions, (2) Measurement of sodium void reactivity effect in a core where axial blanket was replaced with a sodium layer and (3) Measurement of various nuclear characteristics in a nitride fuel region. This report describes methods and results of the above experiments and method of analysis.

Journal Articles

Pre-test analysis method using a neural network for control-rod withdrawal tests of HTTR

Ono, Tomio*; Subekti, M.*; Kudo, Kazuhiko*; Takamatsu, Kuniyoshi; Nakagawa, Shigeaki; Nabeshima, Kunihiko

Nihon Genshiryoku Gakkai Wabun Rombunshi, 4(2), p.115 - 126, 2005/06

Control-rod withdrawal tests simulating reactivity insertion are carried out in the HTTR to verify the inherent safety features of HTGRs. This paper describes pre-test analysis method using artificial neural networks to predict the changes of reactor power and reactivity. The network model applied in this study is based on recurrent neural networks. The inputs of the network are the changes of the central control rods position and other significant core parameters, and the outputs are the changes of reactor power and reactivity. Furthermore, Time Synchronizing Signal(TSS) is added to input to improve the modeling of time series data. The actual tests data, which were previously carried out in the HTTR, were used for learning the model of the plant dynamics. After the learning, the network can predict the changes of reactor power and reactivity in the following tests.

Journal Articles

Stability of magnesite and its high-pressure form in the lowermost mantle

Isshiki, Maiko*; Irifune, Tetsuo*; Hirose, Kei*; Ono, Shigeaki*; Oishi, Yasuo*; Watanuki, Tetsu; Nishibori, Eiji*; Takata, Masaki*; Sakata, Makoto*

Nature, 427(6969), p.60 - 63, 2004/01

 Times Cited Count:205 Percentile:96.47(Multidisciplinary Sciences)

no abstracts in English

Journal Articles

Post-spinel transition in Mg$$_{2}$$SiO$$_{4}$$ determined by high ${it P-T}$ in situ X-ray diffractometry

Katsura, Tomoo*; Yamada, Hitoshi*; Shimmei, Toru*; Kubo, Atsushi*; Ono, Shigeaki*; Kanzaki, Masami*; Yoneda, Akira*; Walter, M. J.*; Ito, Eiji*; Urakawa, Satoru*; et al.

Physics of the Earth and Planetary Interiors, 136(1-2), p.11 - 24, 2003/04

 Times Cited Count:162 Percentile:94.39(Geochemistry & Geophysics)

no abstracts in English

Journal Articles

${it In situ}$ observation of ilmenite-perovskite phase transition in MgSiO$$_{3}$$ using synchrotron radiation

Ono, Shigeaki*; Katsura, Tomoo*; Ito, Eiji*; Kanzaki, Masami*; Yoneda, Akira*; Walter, M.*; Urakawa, Satoru*; Utsumi, Wataru; Funakoshi, Kenichi*

Geophysical Research Letters, 28(5), p.835 - 838, 2001/03

 Times Cited Count:74 Percentile:87(Geosciences, Multidisciplinary)

no abstracts in English

Journal Articles

Thermoelastic properties of the high-pressure phase of SnO$$_{2}$$ determined by in situ X-ray observations up to 30GPa and 1400K

Ono, Shigeaki*; Ito, Eiji*; Katsura, Tomoo*; Yoneda, Akira*; Walter, M.*; Urakawa, Satoru*; Utsumi, Wataru; Funakoshi, Kenichi*

Physics and Chemistry of Minerals, 27(9), p.618 - 622, 2000/11

 Times Cited Count:42 Percentile:80.3(Materials Science, Multidisciplinary)

no abstracts in English

Journal Articles

Hybrid monitoring system for high temperature gas cooling reactor

Nabeshima, Kunihiko; Tuerkcan, E.*; Suzudo, Tomoaki; Nakagawa, Shigeaki; Inoue, K.*; Oono, Tomio*; *; Suzuki, Katsuo

Proc. of Human-Computer Interaction International'99, 2, p.1187 - 1191, 1999/00

no abstracts in English

Journal Articles

Experimental study of the large-scale axially heterogeneous liquid-metal fast breeder reactor at the fast critical assembly; Power distribution measurements and their analyses

Iijima, Susumu; Obu, Makoto; *; Ono, Akio; ; Okajima, Shigeaki

Nuclear Science and Engineering, 100, p.496 - 506, 1988/12

 Times Cited Count:2 Percentile:31.99(Nuclear Science & Technology)

no abstracts in English

Journal Articles

Reactor physics experiments and analyses on high conversion light water reactor

Osugi, Toshitaka; Okajima, Shigeaki; Ono, Akio; Obu, Makoto; ;

Proc. ANS Int. Reactor Physics Conf., Vol. 2, p.361 - 370, 1988/00

no abstracts in English

Oral presentation

On-line monitoring for High Temperature Engineering Test Reactor (HTTR) using neural networks

Nabeshima, Kunihiko; Nakagawa, Shigeaki; Makino, Jun*; Matsuishi, Tomomi*; Subekti, M.*; Ono, Tomio*; Kudo, Kazuhiko*

no journal, , 

The neural networks have been utilized in on-line monitoring-system of High Temperature Engineering Tested Reactor (HTTR) with thermal power of 30MW. From the real-time test results during "reactivity insertion test; control rod withdrawal test" and "coolant flow reduction test", the monitoring system with neural networks showed good prediction and reliable detection performances.

Oral presentation

Soundness confirmation of systems and instruments by cold test of HTTR

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

no journal, , 

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.

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