Journal of Thermal Science, 24(3), p.295 - 301, 2015/06
Before rise-to-power tests, the actual measured value of heat released from the Reactor Pressure Vessel (RPV) or removed by the Vessel Cooling System (VCS) cannot be obtained. It is difficult for operators to evaluate the reactor outlet coolant temperature supplied from the High Temperature Engineering Test Reactor (HTTR) before rise-to-power tests. Therefore, when the actual measured value of heat released from the RPV or removed by the VCS are changed during rise-to-power tests, operators need to evaluate quickly, within a few minutes, the heat removed by the VCS and the reactor outlet coolant temperature of 30 (MW), at the 100% of the reactor power, before the temperature achieves to 967 (C) which is the maximum temperature limit generating the reactor scram. In this paper, a rapid evaluation method for use by operators is presented.
Tochio, Daisuke; Nakagawa, Shigeaki; Furusawa, Takayuki*
Nihon Genshiryoku Gakkai Wabun Rombunshi, 4(2), p.147 - 155, 2005/06
High Temperature Engineering Test Reactor (HTTR) of high temperature gas-cooled reactor at JAERI achieved the reactor outlet coolant temperature of 950C for the first time in the world at Apr. 19, 2004. To remove of generated heat at reactor core and to hold reactor inlet coolant temperature as specified temperature, heat exchangers in HTTR main cooling system should have designed heat exchange performance. In this report, heat exchanger performance is evaluated based on measurement data in high temperature test operation. And it is confirmed the adequacy of heat exchanger designing method by comparison of evaluated value with designed value.
Takamatsu, Kuniyoshi; Nakagawa, Shigeaki
JAERI-Tech 2005-030, 21 Pages, 2005/05
The High Temperature engineering Test Reactor (HTTR) is a graphite moderated and gas cooled reactor with the thermal power of 30MW and the reactor outlet coolant temperature of 850C/950C. Rise-to-power test in the HTTR was performed from March 31th to May 1st in 2004 as phase 5 test up to 30MW in the high temperature test operation mode. It was confirmed that the thermal reactor power and the reactor outlet coolant temperature reached to 30MW and 950C respectively on April 19th. Achievement of the reactor outlet coolant temperature of 950C is the first time in Japan as well as the world. This report describes proposal for evaluation methods of reactor outlet coolant temperature in the HTGRs through the HTTR operation experiments. The equation is derived from relationships among PRM reading values, reactor outlet coolant temperature, reactor thermal power and heat removal by VCS. The deliberation processes in this study will be applicable to the research and developments of HTGRs in the future.
Ashikagaya, Yoshinobu; Kawasaki, Tomokatsu; Yoshino, Toshiaki; Ishida, Keiichi
JAERI-Tech 2005-010, 81 Pages, 2005/03
no abstracts in English
Iyoku, Tatsuo; Nakagawa, Shigeaki; Takamatsu, Kuniyoshi
UTNL-R-0446, p.14_1 - 14_9, 2005/03
no abstracts in English
Fujikawa, Seigo; Hayashi, Hideyuki; Nakazawa, Toshio; Kawasaki, Kozo; Iyoku, Tatsuo; Nakagawa, Shigeaki; Sakaba, Nariaki
Journal of Nuclear Science and Technology, 41(12), p.1245 - 1254, 2004/12
A High Temperature Gas-cooled Reactor (HTGR) is particularly attractive due to its capability of producing high-temperature helium gas and to its inherent safety characteristics. The High Temperature Engineering Test Reactor (HTTR), which is the first HTGR in Japan, achieved its rated thermal power of 30MW and reactor-outlet coolant temperature of 950C on 19 April 2004. During the high-temperature test operation which is the final phase of the rise-to-power tests, reactor characteristics and reactor performance were confirmed, and reactor operations were monitored to demonstrate the safety and stability of operation. The reactor-outlet coolant temperature of 950C makes it possible to extend high-temperature gas-cooled reactor use beyond the field of electric power. Also, highly effective power generation with a high-temperature gas turbine becomes possible, as does hydrogen production from water. The achievement of 950C will be a major contribution to the actualization of producing hydrogen from water using the high-temperature gas-cooled reactors. This report describes the results of the high-temperature test operation of the HTTR.
Sakaba, Nariaki; Nakagawa, Shigeaki; Furusawa, Takayuki*; Emori, Koichi; Tachibana, Yukio
Nihon Genshiryoku Gakkai Wabun Rombunshi, 3(4), p.388 - 395, 2004/12
Chemistry control is important for the helium coolant of High Temperature Gas-cooled Reactors (HTGRs) because impurities cause oxidation of the graphite used in the core and corrosion of high temperature materials used in the heat exchanger. In the High Temperature Engineering Test Reactor (HTTR) which is the first HTGR in Japan, the chemical impurity concentration is restricted and its behaviour is monitored during reactor operations. The impurity is reduced by the helium purification system and the concentration is measured by the helium sampling system installed to the primary and secondary helium system, continuously. This paper describes the impurity behaviour during the rise-to-power test which is the initial power-up of the HTTR. Also, the amount of the emitted impurity to the primary circuit from the graphite component and insulator used at the concentric hot gas duct are evaluated. During the power up, any abnormal impurity increases were not obtained and the chemical composition of the primary circuit is sufficiently in the stability area to avoid carbon deposition.
Takamatsu, Kuniyoshi; Nakagawa, Shigeaki; Sakaba, Nariaki; Takada, Eiji*; Tochio, Daisuke; Shimakawa, Satoshi; Nojiri, Naoki; Goto, Minoru; Shibata, Taiju; Ueta, Shohei; et al.
JAERI-Tech 2004-063, 61 Pages, 2004/10
The High Temperature engineering Test Reactor (HTTR) is a graphite moderated and gas cooled reactor with the thermal power of 30MW and the reactor outlet coolant temperature of 850C/950C. Rise-to-power test in the HTTR was performed from March 31th to May 1st in 2004 as phase 5 test up to 30MW in the high temperature test operation mode. It was confirmed that the thermal reactor power and the reactor outlet coolant temperature reached to 30MW and 950C respectively on April 19th in the single operation mode using only the primary pressurized water cooler. The parallel loaded operation mode using the intermediate heat exchanger and the primary pressurized water cooler was performed from June 2nd and JAERI (Japan Atomic Energy Research Institute) obtained the certificate of the pre-operation test on June 24th from MEXT (Ministry of Education Culture Sports Science and Technology) after all the pre-operation tests were passed successfully in the high temperature test operation mode. Achievement of the reactor-outlet coolant temperature of 950C is the first time in the world. It is possible to extend highly effective power generation with a high-temperature gas turbine and produce hydrogen from water with a high-temperature. This report describes the results of the high-temperature test operation of the HTTR.
Nakagawa, Shigeaki; Tachibana, Yukio; Takamatsu, Kuniyoshi; Ueta, Shohei; Hanawa, Satoshi
Nuclear Engineering and Design, 233(1-3), p.291 - 300, 2004/10
The High Temperature Gas-cooled Reactor (HTGR) is particularly attractive due to its capability of producing high temperature helium gas and due to its inherent safety characteristics. The High Temperature Engineering Test Reactor (HTTR), which is the first HTGR in Japan, was successfully constructed at the Oarai Research Establishment of the Japan Atomic Energy Research Institute. The HTTR achieved full power of 30MW at a reactor outlet coolant temperature of about 850C on December 7, 2001 during the "rise-to-power tests". Two kinds of tests were carried out during the "rise-to-power tests". One is commissioning test to get operation permit by the government and another is test to confirm a performance of the reactor, heat exchanger, control system. From the test results of the "rise-to-power tests" up to 30MW, the functionality of the reactor and the cooling system were confirmed, and it was also confirmed that an operation of reactor facility can be performed safely.
Ueta, Shohei; Takada, Eiji*; Sumita, Junya; Shimizu, Atsushi; Ashikagaya, Yoshinobu; Umeda, Masayuki; Sawa, Kazuhiro
JAERI-Tech 2004-047, 87 Pages, 2004/06
In the radiation shielding design of the High Temperature Engineering Test Reactor (HTTR), strong attention is needed to avoid especially upward neutron streaming. Shielding performance test have been carried out in the Rise-to-power test up to full power operation of 30MW. The measured dose equivalent rates in unrestricted area were lower than the detection limit for neutron-ray, and background level for -ray. The neutron dose equivalent rate measured in the stand pipes room was about 120Sv/h at full power operation, which was much lower than the shielding design (330 mSv/h) and the prediction (10 mSv/h).
Saito, Kenji; Nakagawa, Shigeaki; Hirato, Yoji; Kondo, Makoto; Sawahata, Hiroaki; Tsuchiyama, Masaru*; Ando, Toshio*; Motegi, Toshihiro; Mizushima, Toshihiko; Nakazawa, Toshio
JAERI-Tech 2004-042, 26 Pages, 2004/04
The reactor control system of HTTR is composed of the reactor power control system, the reactor inlet coolant temperature control system, the primary coolant flow rate control system and so on. The reactor control system of HTTR achieves reactor power 30MW, reactor outlet coolant temperature 850C, reactor inlet coolant temperature 395C under the condition that primary coolant flow rate is fixed. In the Rise-to-Power Test, the performance test of the reactor inlet coolant temperature control system was carried out in order to confirm the control capability of this control system. This report shows the test results of performance test. As a result, the control parameters, which can control the reactor inlet coolant temperature stably during the reactor operation, were successfully selected. And it was confirmed that the reactor inlet coolant temperature control system has the capability of controlling the reactor inlet coolant temperature stably against any disturbances on the basis of operational condition of HTTR.
Furusawa, Takayuki; Sumita, Junya; Ueta, Shohei; Nemoto, Takahiro; Oyama, Sunao*; Kamata, Takashi
JAERI-Tech 2004-024, 46 Pages, 2004/03
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.
Ueta, Shohei; Emori, Koichi; Tobita, Tsutomu*; Takahashi, Masashi*; Kuroha, Misao; Ishii, Taro*; Sawa, Kazuhiro
JAERI-Research 2003-025, 59 Pages, 2003/11
In the safety design requirements for the High Temperature Engineering Test Reactor (HTTR) fuel, it is determined that "the as-fabricated failure fraction shall be less than 0.2%" and "the additional failure fraction shall be small through the full service period". Therefore the failure fraction should be quantitatively evaluated during the HTTR operation. In order to measure the primary coolant activity, primary coolant radioactivity signals the in safety protection system, the fuel failure detection (FFD) system and the primary coolant sampling system are provided in the HTTR. The fuel and fission product behavior was evaluated based on measured data in the rise-to-power tests (1) to (4). The measured fractional releases are constant at 210 up to 60% of the reactor power, and then increase to 710 at full power operation. The prediction shows good agreement with the measured value. These results showed that the release mechanism varied from recoil to diffusion of the generated fission gas from the contaminated uranium in the fuel compact matrix.
Ueta, Shohei; Sumita, Junya; Emori, Koichi; Takahashi, Masashi*; Sawa, Kazuhiro
Journal of Nuclear Science and Technology, 40(9), p.679 - 686, 2003/09
no abstracts in English
Shibata, Taiju; Kikuchi, Takayuki; Miyamoto, Satoshi*; Ogura, Kazutomo*
Nuclear Engineering and Design, 223(2), p.133 - 143, 2003/08
The High Temperature Engineering Test Reactor (HTTR) can provide very large spaces at high temperatures for irradiation tests. The I-I type irradiation equipment was developed as the first irradiation rig. It will be served for an in-pile creep test on a stainless steel with large standard size specimens. It uses the ambient high temperature of the core for the irradiation temperature control. The target irradiation temperatures are 550 and 600C with the target temperature deviation of 3C. In this study, the irradiation temperature changes at transient conditions were analyzed by an FEM code and the temperature controllability of the equipment was examined by a mockup test. The controllability was evaluated with the measured temperature transient data at the core graphite components in the Rise-to-Power tests of the HTTR. The result indicates that the temperature control method of the equipment is effective to keep the irradiation temperature stable in the irradiation test.
Takeda, Takeshi; Tachibana, Yukio
Nuclear Engineering and Design, 223(1), p.25 - 40, 2003/07
no abstracts in English
Takamatsu, Kuniyoshi; Nakazawa, Toshio; Furusawa, Takayuki; Homma, Fumitaka; Saito, Kenji; Kokusen, Shigeru; Kamata, Takashi; Ota, Yukimaru; Ishii, Yoshiki; Emori, Koichi
JAERI-Tech 2003-062, 94 Pages, 2003/06
no abstracts in English
Takeda, Takeshi; Tachibana, Yukio; Iyoku, Tatsuo; Takenaka, Satsuki*
Annals of Nuclear Energy, 30(7), p.811 - 830, 2003/05
no abstracts in English
Sakaba, Nariaki; Nakagawa, Shigeaki; Takada, Eiji*; Nojiri, Naoki; Shimakawa, Satoshi; Ueta, Shohei; Sawa, Kazuhiro; Fujimoto, Nozomu; Nakazawa, Toshio; Ashikagaya, Yoshinobu; et al.
JAERI-Tech 2003-043, 59 Pages, 2003/03
HTTR plans a high temperature test operation as the fifth step of the rise-to-power tests to achieve a reactor outlet coolant temperature of 950 degrees centigrade in the 2003 fiscal year. Since HTTR is the first HTGR in Japan which uses coated particle fuel as its fuel and helium gas as its coolant, it is necessary that the plan of the high temperature test operation is based on the previous rise-to-power tests with a thermal power of 30 MW and a reactor outlet coolant temperature at 850 degrees centigrade. During the high temperature test operation, reactor characteristics, reactor performances and reactor operations are confirmed for the safety and stability of operations. This report describes the evaluation result of the safety confirmations of the fuel, the control rods and the intermediate heat exchanger for the high temperature test operation. Also, problems which were identified during the previous operations are shown with their solution methods. Additionally, there is a discussion on the contents of the high temperature test operation. As a result of this study, it is shown that the HTTR can safely achieve a thermal power of 30MW with the reactor outlet coolant temperature at 950 degrees centigrade.
Sakaba, Nariaki; Nakazawa, Toshio; Kawasaki, Kozo; Urakami, Masao*; Saishu, Sadanori*
JAERI-Tech 2003-041, 106 Pages, 2003/03
In the second stage of the research and development for a high-temperature helium-leak detection system, the temperature sensor using optical fibres was studied. The sensor detects the helium leakage by the temperature inclease surrounded opitical fibre with or without heat insulator. Moreover, the applicability of high temperature equipments as the HTTR system was studied. With the sensor we detected 5.0-20.0 cm/s helium leakages within 60 minutes. Also it was possible to detect earlier when the leakage level is at 20.0 cm/s.