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Journal Articles

Improving the safety of the high temperature gas-cooled reactor "HTTR" based on Japan's new regulatory requirements

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

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.

Journal Articles

Measurement of temperature response of intermediate heat exchanger in heat application system abnormal simulating test using HTTR

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 120$$^{circ}$$C 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.

Journal Articles

Investigation of absorption characteristics for thermal-load fluctuation using HTTR

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:15.39(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.

JAEA Reports

HTTR thermal load fluctuation test (non-nuclear heating test); Confirmation of HTGR system response against temperature transient

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.

Journal Articles

Operation and maintenance experience from the HTTR database

Shimizu, Atsushi; Furusawa, Takayuki; Homma, Fumitaka; Inoi, Hiroyuki; Umeda, Masayuki; Kondo, Masaaki; Isozaki, Minoru; Fujimoto, Nozomu; Iyoku, Tatsuo

Journal of Nuclear Science and Technology, 51(11-12), p.1444 - 1451, 2014/11

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

JAEA has kept up a data-base system of operation and maintenance experiences of the HTTR. The objective of this system is to share the information obtained operation and maintenance experiences and to make use of lessons learned and knowledge into a design, construction and operation managements of the future HTGR. More than one thousand records have been registered into the system between 1997 and 2012. This paper describes the status of the data-base system, and provides suggestions for improvement from four experiences: (1) performance degradation of helium compressors; (2) malfunction of reserved shutdown system in reactivity control system; (3) maintenance experiences of emergency gas turbine generators; and (4) experiences of the Great East Japan Earthquake. These experiences are extracted from the system as important lessons learned to be expected to apply for design, construction and operation managements of future HTGR.

Journal Articles

Development of the maintenance technologies for the future high-temperature gas cooled reactor (HTGR) using operating experiences acquired in high-temperature engineering test reactor (HTTR)

Shimazaki, Yosuke; Homma, Fumitaka; Sawahata, Hiroaki; Furusawa, Takayuki; Kondo, Masaaki

Journal of Nuclear Science and Technology, 51(11-12), p.1413 - 1426, 2014/11

 Times Cited Count:2 Percentile:19.81(Nuclear Science & Technology)

JAEA Reports

Outline of device to confirm the responsiveness of control systems for HTTR

Homma, Fumitaka; Hirato, Yoji; Saito, Kenji

JAEA-Technology 2014-010, 64 Pages, 2014/05

JAEA-Technology-2014-010.pdf:35.55MB

After an accident at Fukushima Daiichi Nuclear Plant, the High Temperature Engineering Test Reactor (HTTR) should be kept shut-down till adaptability to the new nuclear safety regulation established by the Nuclear Regulation Authority (NRA) will be confirmed. However, we have to keep the operational ability for the HTTR is indispensable. The operation training for the HTTR using the simulator of light water reactors is not effective. Because the HTTR is the only test reactor in the world and one has many characteristics different from light water reactors. It is an urgent problem to utilize the device which confirms the responsiveness of the control systems for the HTTR (simulator) as a simulator for operation training. This report shows specifications of device, results of simulation and the matter which we should carry out in future.

Journal Articles

Development of operation and maintenance technology for HTGRs by using HTTR (High Temperature engineering Test Reactor)

Shimizu, Atsushi; Kawamoto, Taiki; Tochio, Daisuke; Saito, Kenji; Sawahata, Hiroaki; Homma, Fumitaka; Furusawa, Takayuki; Saikusa, Akio; Takada, Shoji; Shinozaki, Masayuki

Nuclear Engineering and Design, 271, p.499 - 504, 2014/05

 Times Cited Count:4 Percentile:36.81(Nuclear Science & Technology)

The long term high temperature operation using HTTR was carried out to establish the technical basis of HTGR in the high temperature test operation mode during 50-day since January till March, 2010. It is necessary to demonstrate the stability of plant during long-term operation in order to attain the stable supply of the high temperature heat to the planned heat utilization system of HTTR. Test data obtained in the operation were evaluated for the technical issues which were extracted before the operation. As the results, Stability and reliability of the components and facility was demonstrated by evaluating the heat transfer performance of high temperature components, the performance of pressure control to compensate helium gas leak, the reliability of the dynamic components such as helium gas circulators, the performance of heat-up protection of radiation shielding. Through the operation, the technical basis for the operation and maintenance technology of HTGRs was established.

JAEA Reports

Integrity check of emergency generator for the HTTR after the Tohoku-Pacific Ocean Earthquake

Homma, Fumitaka; Inoi, Hiroyuki; Watanabe, Shuji; Fukutani, Koji*

JAEA-Technology 2013-034, 57 Pages, 2013/12

JAEA-Technology-2013-034.pdf:11.01MB

Emergency generator of HTTR started in the blackout occurred just after an Tohoku Pacific Ocean Earthquake on March 11, 2011 with an intensity of 5 upper on the Japanese seven stage seismic scale and its duration time was long. In addition, we suffer from multiple severe aftershocks just after the start of emergency generators. Emergency generator of HTTR was able to supply output electric power sufficiently and stably to required loads. We carried on integrity check of the emergency generator for the HTTR after the earthquake. In particular, we put emphasis on finding faults caused by thee earthquake shaking. As a result, we found that the erosion in a combustion liner, and the condition of erosion was very strange and rare. Therefore, we carried out investigations of causes of erosion, and change of specifications for combustion liner to prevent erosion. This measure improve the reliability for the further Large-Scale earthquake.

Journal Articles

Development of operation and maintenance technology of HTTR (High Temperature engineering Test Reactor)

Shimizu, Atsushi; Kawamoto, Taiki; Tochio, Daisuke; Saito, Kenji; Sawahata, Hiroaki; Homma, Fumitaka; Furusawa, Takayuki; Saikusa, Akio; Shinozaki, Masayuki

Proceedings of 6th International Topical Meeting on High Temperature Reactor Technology (HTR 2012) (USB Flash Drive), 8 Pages, 2012/10

To establish the technical basis of HTGR, the long term high temperature operation using HTTR was carried out during 50-day in 2010. It is necessary to demonstrate the stability of plant during long-term operation and the reliability of components and facilities special to HTGRs, in order to attain the stable supply of the high temperature heat to the planned hydrogen production system of HTTR. Test data obtained in the operation were evaluated for the technical issues which were extracted before the operation. As the results, stability and reliability of the components and facility special to HTGRs was demonstrated by evaluating the heat transfer performance of high temperature components, the helium gas leak tightness, the reliability of the dynamic components such as helium gas circulators, the performance of heat-up protection of radiation shielding. Through the operation, the technical basis for the operation and maintenance technology of HTGRs were established.

JAEA Reports

The Approaches of safety design and safety evaluation at HTTR (High Temperature Engineering Test Reactor)

Iigaki, Kazuhiko; Saikusa, Akio; Sawahata, Hiroaki; Shinozaki, Masayuki; Tochio, Daisuke; Homma, Fumitaka; Tachibana, Yukio; Iyoku, Tatsuo; Kawasaki, Kozo; Baba, Osamu*

JAEA-Review 2006-010, 90 Pages, 2006/07

JAEA-Review-2006-010.pdf:5.65MB

Gas Cooled Reactor has long history of nuclear development, and High Temperature Gas Cooled Reactor (HTGR) has been expected that it can be supply high temperature energy to chemical industry and to power generation from the points of view of the safety, the efficiency, the environment and the economy. The HTGR design is tried to installed passive safety equipment. The current licensing review guideline was made for a Low Water Reactor (LWR) on safety evaluation therefore if it would be directly utilized in the HTGR it needs the special consideration for the HTGR. This paper describes that investigation result of the safety design and the safety evaluation traditions for the HTGR, comparison the safety design and safety evaluation feature for the HTGT with it's the LWR, and reflection for next HTGR based on HTTR operational experiment.

JAEA Reports

Findings of the reactor automatic shutdown caused by a signal of a primary coolant flow rate of the PPWC:Low in the HTTR

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

JAERI-Tech-2003-062.pdf:26.47MB

no abstracts in English

Journal Articles

Safety shutdown of the High Temperature Engineering Test Reactor during loss of off-site electric power simulation test

Takeda, Takeshi; Nakagawa, Shigeaki; Homma, Fumitaka*; Takada, Eiji*; Fujimoto, Nozomu

Journal of Nuclear Science and Technology, 39(9), p.986 - 995, 2002/09

 Times Cited Count:4 Percentile:30.46(Nuclear Science & Technology)

no abstracts in English

JAEA Reports

Test program for reactor control system in rise-to-power test in HTTR

Nakagawa, Shigeaki; Saito, Kenji; Homma, Fumitaka; Tachibana, Yukio; Kunitomi, Kazuhiko

JAERI-Tech 2000-009, p.88 - 0, 2000/02

JAERI-Tech-2000-009.pdf:6.19MB

no abstracts in English

Journal Articles

Instrumentation and control system of the HTTR

Saito, Kenji; Homma, Fumitaka; Omata, Toru; Aono, Tetsuya; Kawaji, Satoshi; Kawasaki, Kozo; Iyoku, Tatsuo

Proceedings of International Topical Meeting on Nuclear Plant Instrumentation, Controls, and Human-Machine Interface Technologies (NPIC&HMIT 2000) (CD-ROM), 8 Pages, 2000/00

no abstracts in English

Oral presentation

Development of preservation technology for high temperature gas-cooled reactor

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 950$$^{circ}$$C 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.

Oral presentation

Completion of long term high temperature operation of HTTR (High Temperature Engineering Test Reactor), 5; Operation and maintenance

Shimizu, Atsushi; Kawamoto, Taiki; Tochio, Daisuke; Homma, Fumitaka; Sawahata, Hiroaki; Furusawa, Takayuki

no journal, , 

For the long term high temperature operation with HTTR, issues for systems and components, which were extracted based on result of long term rated operation, were solved. As the result, the followings were confirmed; deviation of temperature, flow rate and pressure of the primary and secondary coolant were sufficiently restricted against the disturbance of temperature of atmosphere during day and night. The whole plant was operated stable. It was confirmed that the secondary coolant was stably supplied. New findings were acquired for the operation and maintenance of systems and components for future HTGR development.

Oral presentation

Development of operation and maintenance technique with long term high temperature operation in HTTR, 2; Operation and maintenance of facilities and equipments unique for HTGRs

Shimizu, Atsushi; Kawamoto, Taiki; Tochio, Daisuke; Homma, Fumitaka; Sawahata, Hiroaki; Furusawa, Takayuki

no journal, , 

no abstracts in English

Oral presentation

The Countermeasures of SBO by taking account of HTTR characteristics

Kondo, Makoto; Homma, Fumitaka; Sawahata, Hiroaki; Hirato, Yoji; Kawamoto, Taiki; Suzuki, Hisashi; Ono, Masato

no journal, , 

no abstracts in English

Oral presentation

Improvement of heat-resistant wide range monitoring neutron detector for HTTR

Kozawa, Takayuki; Hirato, Yoji; Homma, Fumitaka

no journal, , 

no abstracts in English

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