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Journal Articles

Seismic classification of high temperature engineering test reactor

Ono, Masato; Shimizu, Atsushi; Ohashi, Hirofumi; Hamamoto, Shimpei; Inoi, Hiroyuki; Tokuhara, Kazumi*; Nomoto, Yasunobu*; Shimazaki, Yosuke; Iigaki, Kazuhiko; Shinozaki, Masayuki

Nuclear Engineering and Design, 386, p.111585_1 - 111585_9, 2022/01

In the late 1980s during the design stage, the seismic classification of the high temperature engineering test reactor (HTTR) was formulated. Owing to the lack of operation experiences of the HTTR to sufficiently understand the safety characteristics of high temperature gas cooled reactors (HTGR) at that time, the seismic classification of commercial light water reactors (LWR) was applied to HTTR. However, the subsequent operation experiences and test results using HTTR made it clear that the seismic classification of commercial LWR was somewhat too conservative for the HTGR. As a result, Class S facilities were downgraded compared to the commercial LWR. Moreover, the validity of the new seismic classification is confirmed. In June 2020, the Nuclear Regulatory Authority approved that the result of the seismic classification conformed to the standard rules of the reactor installation change.

JAEA Reports

Impact assessment for internal flooding in HTTR (High temperature engineering test reactor)

Tochio, Daisuke; Nagasumi, Satoru; Inoi, Hiroyuki; Hamamoto, Shimpei; Ono, Masato; Kobayashi, Shoichi; Uesaka, Takahiro; Watanabe, Shuji; Saito, Kenji

JAEA-Technology 2021-014, 80 Pages, 2021/09

JAEA-Technology-2021-014.pdf:5.87MB

In response to the new regulatory standards established in response to the accident at TEPCO's Fukushima Daiichi Nuclear Power Station in March 2011, measures and impact assessments related to internal flooding at HTTR were carried out. In assessing the impact, considering the characteristics of the high-temperature gas-cooled reactor, flooding due to assumed damage to piping and equipment, flooding due to water discharge from the system installed to prevent the spread of fire, and flooding due to damage to piping and equipment due to an earthquake. The effects of submersion, flooding, and flooding due to steam were evaluated for each of them. The impact of the overflow of liquids containing radioactive materials outside the radiation-controlled area was also evaluated. As a result, it was confirmed that flooding generated at HTTR does not affect the safety function of the reactor facility by taking measures.

JAEA Reports

Interim activity status report of "the group for investigation of reasonable safety assurance based on graded approach" (from September, 2019 to September, 2020)

Yonomoto, Taisuke; Nakashima, Hiroshi*; Sono, Hiroki; Kishimoto, Katsumi; Izawa, Kazuhiko; Kinase, Masami; Osa, Akihiko; Ogawa, Kazuhiko; Horiguchi, Hironori; Inoi, Hiroyuki; et al.

JAEA-Review 2020-056, 51 Pages, 2021/03

JAEA-Review-2020-056.pdf:3.26MB

A group named as "The group for investigation of reasonable safety assurance based on graded approach", which consists of about 10 staffs from Sector of Nuclear Science Research, Safety and Nuclear Security Administration Department, departments for management of nuclear facility, Sector of Nuclear Safety Research and Emergency Preparedness, aims to realize effective graded approach (GA) about management of facilities and regulatory compliance of JAEA. The group started its activities in September, 2019 and has had discussions through 10 meetings and email communications. In the meetings, basic ideas of GA, status of compliance with new regulatory standards at each facility, new inspection system, etc were discussed, while individual investigation at each facility were shared among the members. This report is compiled with expectation that it will help promote rational and effective safety management based on GA by sharing contents of the activity widely inside and outside JAEA.

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

Comprehensive seismic evaluation of HTTR against the 2011 off the Pacific coast of Tohoku Earthquake

Ono, Masato; Iigaki, Kazuhiko; Sawahata, Hiroaki; Shimazaki, Yosuke; Shimizu, Atsushi; Inoi, Hiroyuki; Kondo, Toshinari; Kojima, Keidai; Takada, Shoji; Sawa, Kazuhiro

Journal of Nuclear Engineering and Radiation Science, 4(2), p.020906_1 - 020906_8, 2018/04

On March 11th, 2011, the 2011 off the Pacific coast of Tohoku Earthquake of magnitude 9.0 occurred. When the great earthquake occurred, the High Temperature Engineering Test Reactor (HTTR) had been stopped under the periodic inspection and maintenance of equipment and instruments. A comprehensive integrity evaluation was carried out for the HTTR facility because the maximum seismic acceleration observed at the HTTR exceeded the maximum value of design basis earthquake. The concept of comprehensive integrity evaluation is divided into two parts. One is the "visual inspection of equipment and instruments". The other is the "seismic response analysis" for the building structure, equipment and instruments using the observed earthquake. All equipment and instruments related to operation were inspected in the basic inspection. The integrity of the facilities was confirmed by comparing the inspection results or the numerical results with their evaluation criteria. As the results of inspection of equipment and instruments associated with the seismic response analysis, it was judged that there was no problem for operation of the reactor, because there was no damage and performance deterioration. The integrity of HTTR was also supported by the several operations without reactor power in cold conditions of HTTR in 2011, 2013 and 2015. Additionally, the integrity of control rod guide blocks was also confirmed visually when three control rod guide blocks and six replaceable reflector blocks were taken out from reactor core in order to change neutron startup sources in 2015.

Journal Articles

Confirmation of seismic integrity of HTTR against 2011 Great East Japan Earthquake

Ono, Masato; Iigaki, Kazuhiko; Shimazaki, Yosuke; Shimizu, Atsushi; Inoi, Hiroyuki; Tochio, Daisuke; Hamamoto, Shimpei; Nishihara, Tetsuo; Takada, Shoji; Sawa, Kazuhiro; et al.

Proceedings of 24th International Conference on Nuclear Engineering (ICONE-24) (DVD-ROM), 12 Pages, 2016/06

On March 11th, 2011, the Great East Japan Earthquake of magnitude 9.0 occurred. When the great earthquake occurred, the HTTR had been stopped under the periodic inspection and maintenance of equipment and instrument. In the great earthquake, the maximum seismic acceleration observed at the HTTR exceeded the maximum value in seismic design. The visual inspection of HTTR facility was carried out for the seismic integrity conformation of HTTR. The seismic analysis was also carried out using the observed earthquake motion at HTTR site to confirm the integrity of HTTR. The concept of comprehensive integrity evaluation for the HTTR facility is divided into two parts. One is the inspection of equipment and instrument. The other is the seismic response analysis using the observed earthquake. For the basic inspections of equipment and instrument were performed for all them related to the operation of reactor. The integrity of the facilities is confirmed by comparing the inspection results or the numerical results with their evaluation criteria. As the result of inspection of equipment and instrument and seismic response analysis, it was judged that there was no problem to operate the reactor, because there was no damage and performance deterioration, which affects the reactor operation. The integrity of HTTR was also supported by the several operations without reactor power in cold conditions of HTTR in 2011, 2013 and 2015.

Journal Articles

Evaluation on seismic integrity of HTTR core components

Ono, Masato; Iigaki, Kazuhiko; Shimazaki, Yosuke; Tochio, Daisuke; Shimizu, Atsushi; Inoi, Hiroyuki; Hamamoto, Shimpei; Takada, Shoji; Sawa, Kazuhiro

Proceedings of International Topical Meeting on Research Reactor Fuel Management and Meeting of the International Group on Reactor Research (RRFM/IGORR 2016) (Internet), p.363 - 371, 2016/03

HTTR is graphite moderated and helium gas-cooled reactor with prismatic fuel elements and hexagonal blocks. Here, the graphite block is brittle materials and might be damaged by collision of neighboring blocks by the large earthquake. A seismic observation system is installed in the HTTR site to confirm a behavior of a seismic event. On March 11th, 2011, off the Pacific coast of Tohoku Earthquake of magnitude 9.0 occurred. After the accident at the TEPCO Fukushima Daiichi Nuclear Power Station, the safety of nuclear reactors is the highest importance. To confirm the seismic integrity of HTTR core components, the seismic analysis was carried out using the evaluation waves based on the relationship between the observed earthquake motion at HTTR site and frequency transfer function. In parallel, confirmation tests of primary cooling system on cold state and integrity confirmation of reactor buildings and component support structures were also carried out. As a result, it was found that a stress value of the graphite blocks satisfied an allowable value, and the integrity of the HTTR core components was ensured. The integrity of HTTR core components was also supported by the operation without reactor power in cold conditions of HTTR. The obtained data was compared with the normal plant data before the earthquake. As the result, the integrity of the HTTR facilities was confirmed.

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

A Safety evaluation of HTTR core graphite structures against the Great East Japan Earthquake

Iigaki, Kazuhiko; Ono, Masato; Shimazaki, Yosuke; Tochio, Daisuke; Shimizu, Atsushi; Inoi, Hiroyuki; Takada, Shoji; Sawa, Kazuhiro

Mechanical Engineering Journal (Internet), 1(4), p.TEP0021_1 - TEP0021_13, 2014/08

On March 11th, 2011, the Great East Japan Earthquake which is one of the largest earthquakes in japan occurred and the maximum acceleration in observed seismic wave in the HTTR exceeded the design value in a part of input seismic motions. Therefore, a visual inspection, a seismic analysis and a performance confirmation test of facilities were carried out in order to confirm the integrity of facility after the earthquake. The seismic analysis was carried out for the reactor core structures by using the response magnification factor method. As the results of the evaluation, the generated stress in the graphite blocks in the reactor core at the earthquake were well below the allowable values of safety criteria, and thus the structural integrity of the reactor core was confirmed. The integrity of reactor core was also supported by the visual inspections of facilities and the operation without reactor power in cold conditions of HTTR.

Journal Articles

Investigation of chemical characteristics of primary helium gas coolant of HTTR (High Temperature engineering Test Reactor)

Hamamoto, Shimpei; Shimazaki, Yosuke; Furusawa, Takayuki; Nemoto, Takahiro; Inoi, Hiroyuki; Takada, Shoji

Nuclear Engineering and Design, 271, p.487 - 491, 2014/05

 Times Cited Count:5 Percentile:43.74(Nuclear Science & Technology)

The technical basis of helium gas purification control for HTGRs was established by verifying the design of the PHPS of HTTR by showing that the measured concentrations of impurities of primary helium coolant were restricted below the criteria to protect the graphite oxidation, and that the carburization atmosphere was maintained to keep intact of metallic high temperature components, in the 30-day continuous operation and the 50-day long term high temperature operation. The improved analytical model predicted the composition of the impurities such as H$$_{2}$$, CO, H$$_{2}$$O and CO$$_{2}$$, which is determined by the temperature dependency of release of impurities during the rated power operation adequately. In contrast, it was revealed that the measured concentration of H$$_{2}$$O remarkably decreased while the concentration of CO increased in the primary helium coolant in the long term high temperature operation.

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

Investigation on iodine release behavior during the operation of high temperature engineering test reactor (HTTR)

Ueta, Shohei; Inoi, Hiroyuki; Mizutani, Yoshitaka; Ohashi, Hirofumi; Iwatsuki, Jin; Sakaba, Nariaki; Sawa, Kazuhiro

Proceedings of 21st International Conference on Nuclear Engineering (ICONE-21) (DVD-ROM), 4 Pages, 2013/07

Japan Atomic Energy Agency (JAEA) has planned to investigate on iodine release behavior from fuel through the testing operation of High Temperature Engineering Test Reactor (HTTR) in order to contribute to the reasonable estimation of the radiation exposure necessary for the realization of HTGR in the future. In this test, the fractional release of iodine will be measured and evaluated by measuring xenon isotopes, the daughter nuclides of iodine isotopes, in the primary coolant sampling under the loss-of-forced cooling (LOFC) test by which the primary coolant circulator is shut down and/or the manual scram test of HTTR. In parallel, the local area of primary coolant circuit where iodine is plated-out will be evaluated. This paper describes the testing plan and the preliminary analytical study on the release behavior of iodine and xenon isotopes through the operation of HTTR.

Journal Articles

Chemical characteristics of helium coolant of HTTR (High Temperature engineering Test Reactor)

Hamamoto, Shimpei; Shimazaki, Yosuke; Furusawa, Takayuki; Nemoto, Takahiro; Inoi, Hiroyuki; Takada, Shoji

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

Journal Articles

Dust generation and transport behavior in the primary circuit of HTTR

Hamamoto, Shimpei; Shimazaki, Yosuke; Furusawa, Takayuki; Nemoto, Takahiro; Inoi, Hiroyuki

Proceedings of 20th International Conference on Nuclear Engineering and the ASME 2012 Power Conference (ICONE-20 & POWER 2012) (DVD-ROM), 7 Pages, 2012/07

JAEA Reports

Result of long-term operation of HTTR; High-temperature/parallel-loaded 50-days operation

Tochio, Daisuke; Hamamoto, Shimpei; Inoi, Hiroyuki; Shimazaki, Yosuke; Sekita, Kenji; Kondo, Masaaki; Saikusa, Akio; Kameyama, Yasuhiko; Saito, Kenji; Emori, Koichi; et al.

JAEA-Technology 2010-038, 57 Pages, 2010/12

JAEA-Technology-2010-038.pdf:2.36MB

In HTTR, in-service operation is conducted through the rise-to power operation with rated operation or high-temperature test operation from achievement of first criticality at 1998. To make practical use HTGR system, it must be demonstrated to supply stable heat to heat utilization system for long-term. In HTTR, high-temperature/parallel-loaded long-term operation had been performed from January 2010. As the result, it was demonstrated to supply stable heat to heat utilization system for 50 days with HTTR, moreover, various long-term operation data were gained. This paper reports the characteristics of the high-temperature long-term operation for HTTR obtained from the operation.

Journal Articles

Long-term high-temperature operation in the HTTR, 1; Outline and main test results

Shinohara, Masanori; Tochio, Daisuke; Hamamoto, Shimpei; Inoi, Hiroyuki; Shinozaki, Masayuki; Nishihara, Tetsuo; Iyoku, Tatsuo

Proceedings of 5th International Topical Meeting on High Temperature Reactor Technology (HTR 2010) (CD-ROM), 7 Pages, 2010/10

HTTR constructed at the Oarai Research and Development Center of JAEA is the first HTGR in Japan. The reactor thermal power is 30 MW, the reactor maximum outlet coolant temperature is 850 $$^{circ}$$C in rated operation mode and 950 $$^{circ}$$C in high temperature test operation mode. Main objectives of the HTTR are to establish and develop HTGR technology and to demonstrate process heat application. 30-days operation in rated operation mode and 50-days operation in high-temperature operation mode were performed to obtain various characteristic data of HTGR. The main test results are as follows :(1) CPF of the HTTR has excellent confinement ability of fission product which is the highest performance in the world. (2) The measurement temperature of the core internals is good agreement with the design value so that their structural integrity is maintained. (3) The intermediate heat exchanger keeps excellent heat transfer performance from beginning of operation.

JAEA Reports

Maintenance of the emergency power generators and overhaul of the gas turbine engines in HTTR

Inoi, Hiroyuki; Shimizu, Atsushi; Kameyama, Yasuhiko; Kobayashi, Shoichi; Shinozaki, Masayuki; Ota, Yukimaru; Kubo, Tsukasa*; Emori, Koichi

JAEA-Technology 2009-048, 48 Pages, 2009/10

JAEA-Technology-2009-048.pdf:5.0MB

The emergency power feeders of the High Temperature Engineering Test Reactor (HTTR) have gas turbine generators which are composed of gas turbin engines, generators and current breakers. The gas turbine generators have been overhauled and maintained to keep the performance. The maintenance technology was upgraded by improving their parts and surveillance method on the basis of the operational and maintenance experience. It can be clarified that the deterioration levels and the sudden deterioration timing are judged at an early stage by measuring the max exhaust temperature at the time of start in addition to check the starting time of the Gas Turbine Engines.

JAEA Reports

Result of long-term operation of HTTR; Rated/parallel-loaded 30-days operation

Tochio, Daisuke; Nojiri, Naoki; Hamamoto, Shimpei; Inoi, Hiroyuki; Sekita, Kenji; Kondo, Masaaki; Saikusa, Akio; Kameyama, Yasuhiko; Saito, Kenji; Fujimoto, Nozomu

JAEA-Technology 2009-005, 47 Pages, 2009/05

JAEA-Technology-2009-005.pdf:4.01MB

HTTR is now conducted in-service operation through the rise-to power operation with rated operation or high-temperature test operation from achievement of first criticality at 1998. In order to demonstrate to supply stable heat to heat utilization system for long-term, HTTR was conducted rated/parallel-loaded 30-days operation. This paper reports the characteristics of long-term operation for HTTR.

JAEA Reports

Irradiation performance test of the temperature monitor for the HTGR fuel

Ueta, Shohei; Tobita, Tsutomu*; Sawa, Kazuhiro; Tomimoto, Hiroshi; Kozawa, Takayuki; Inoi, Hiroyuki; Umeda, Masayuki

JAEA-Research 2008-096, 34 Pages, 2009/01

JAEA-Research-2008-096.pdf:10.12MB

The temperature monitors for fuel blocks in high temperature gas reactors during operation are being developed. The temperature monitors consist of alloy wires, with various melting points, sealed in quarts capsules. The temperature can be evaluated in the range from 600 to 1400 $$^{circ}$$C with 22 types of the temperature monitors. The temperature monitors have been irradiated by the capsule in JMTR, and then, PIEs such as X-ray radiograph and EPMA have been carried out. As the results of the PIE, it was estimated that the temperature monitors can be used up to 90 days at 1100 $$^{circ}$$C, or up to 50 days at 1300$$sim$$1350 $$^{circ}$$C.

JAEA Reports

Maintenance of gaseous radwaste treatment system in HTTR

Yamazaki, Kazunori; Kameyama, Yasuhiko; Inoi, Hiroyuki; Arakaki, Etsushi; Shinozaki, Masayuki; Ota, Yukimaru

JAEA-Testing 2008-002, 52 Pages, 2008/03

JAEA-Testing-2008-002.pdf:15.54MB

The High Temperature Engineering Test Reactor (HTTR) has the Gaseous Radwaste Treatment System (GRTS). This system appropriately collects all potentially radioactive gases discharged from the plant. After the gases are decayed with the Decay tank and decreased with the Filtering system, the gases are discharged into the atmosphere under monitoring. This system is maintained every year for keeping the performance. The maintenance is very important. Furthermore, the maintenance is profitable for designing a new High Temperature Gas cooled Reactor. This report describes the newly developed, maintenance items and improvements of the GRTS.

31 (Records 1-20 displayed on this page)