Refine your search:     
Report No.
 - 
Search Results: Records 1-20 displayed on this page of 36

Presentation/Publication Type

Initialising ...

Refine

Journal/Book Title

Initialising ...

Meeting title

Initialising ...

First Author

Initialising ...

Keyword

Initialising ...

Language

Initialising ...

Publication Year

Initialising ...

Held year of conference

Initialising ...

Save select records

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.

JAEA Reports

Improvement in oil seal performance of gas compressor in HTTR, 2

Nemoto, Takahiro; Kaneshiro, Noriyuki*; Sekita, Kenji; Furusawa, Takayuki; Kuroha, Misao; Kawakami, Satoru; Kondo, Masaaki

JAEA-Technology 2015-006, 36 Pages, 2015/03

JAEA-Technology-2015-006.pdf:16.77MB

The High-Temperature engineering Test Reactor (HTTR) has been developed for establishing and upgrading the technical basis of HTGR.HTTR facilities have their structures, systems and a lot of components including reciprocating gas compressors, commonly used to extract and/or discharge reactor coolant helium gas contained in primary/secondary coolant systems. From the fact of the operational experiences of these compressors, seal-oil leakage has been frequently observed, although rod-seal mechanisms with complicated structures are equipped and improved for preventing coolant helium gas. So, we tried to change the rod-seal materials which might be a primary reason of frequent seal-oil leakage, that resulted in decreasing a mass and frequently of seal-oil leakage. It is confirmed that it is important to select adequate materials of rod seal for sliding speed of the piston of the compressor to prevent seal-oil leakage. Additionally, the procedure to estimate seal-oil leakage for each compressor is discussed. This report describes the results of investigation for improvement on seal-oil leak tightness of the compressors in HTTR facilities.

Journal Articles

Investigation on dust captured by quintuple filters installed upstream of primary gas circulators in HTTR

Inaba, Yoshitomo; Hamamoto, Shimpei; Furusawa, Takayuki; Saikusa, Akio; Sakaba, Nariaki

Journal of Nuclear Science and Technology, 51(11-12), p.1373 - 1386, 2014/11

 Times Cited Count:0 Percentile:0.01(Nuclear Science & Technology)

A main objective to install filters upstream of primary gas circulators in the high temperature engineering test reactor (HTTR), besides having a primary helium purification system, is the reduction and removal of circulating dust in the primary circuit. A problem encountered with the filters during the initial operations of the HTTR was that the differential pressure across the filters had increased excessively over the duration of the operations so that the differential pressure would be expected to exceed the limit value regulated in the HTTR operation manual. It was speculated that either the carbon traced back chemical reactions, the debris from mechanical contacts or both of these sources might be captured by the filters. Then, the filters were replaced and inspected to identify the cause of the increase of the filter differential pressure. As a result, it was found that the increase is caused by clogging of the filters by the dust traced back to the physical contact of the piston rings of the gas circulators equipped in the primary helium purification system. Hence, prismatic block-type very high temperature reactors (VHTRs) do not continuously supply carbon dust from the cores in operation.

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)

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.

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.

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.

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

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.

JAEA Reports

Performance-based improvement of the leakage rate test program for the reactor containment of HTTR; Adoption of revised test program containing "Type A, Type B and Type C tests"

Kondo, Masaaki; Kimishima, Satoru*; Emori, Koichi; Sekita, Kenji; Furusawa, Takayuki; Hayakawa, Masato; Kozawa, Takayuki; Aono, Tetsuya; Kuroha, Misao; Ouchi, Hiroshi

JAEA-Technology 2008-062, 46 Pages, 2008/10

JAEA-Technology-2008-062.pdf:11.62MB

The reactor containment of HTTR is tested to confirm leak-tight integrity of itself. "Type A test" has been conducted in accordance with the standard testing method in JEAC4203 since the preoperational verification of the containment was made. Type A tests are identified as basic one for measuring containment leakage rate, it costs much, however. Therefore, the test program for HTTR was revised to adopt an efficient and economical alternatives including "Type B and Type C tests". In JEAC4203-2004, following requirements are specified for adopting alternatives: upward trend of leakage rate by Type A test due to aging should not be recognized; criterion of combined leakage rate with Type B and Type C tests should be established; the criteria for Type A test and combined leakage rate test should be satisfied; correlation between the leakage rates by Type A test and combined leakage rate test should be recognized. Considering the performances of the tests, the policies of corresponding to the requirements were developed, which were accepted by the regulatory agency. This report presents an outline of the tests, identifies issues on the conventional test and summarizes the policies of corresponding to the requirements and of implementing the tests based on the revised program.

JAEA Reports

Water chemistry control in HTTR

Sekita, Kenji; Furusawa, Takayuki; Emori, Koichi; Ishii, Taro*; Kuroha, Misao; Hayakawa, Masato; Ouchi, Hiroshi

JAEA-Technology 2008-057, 45 Pages, 2008/08

JAEA-Technology-2008-057.pdf:12.0MB

A carbon steel used is used for the main material for the components and pipings of the pressurized water cooling system etc. that are the reactor cooling system of the HTTR. Water quality is managed by using the hydrazine in the coolant of the water cooling system to prevent corrosion of the components and deoxidize the coolant. Also, regular analysis is carried out for the confirmation of the water quality. The following results were obtained through the water quality analysis. (1) In the pressurized water cooling system, the coolant temperature rises higher due to the heat removal of the primary coolant. So, the ammonia was formed in the thermal decomposition of the hydrazine. The electric conductivity increased, while the concentration of the hydrazine decreased, there was no problem as the plan it. (2) Thermal decomposition of the hydrazine was not occurred in the auxiliary water cooling system and vessel cooling system because of the coolant temperature was low. (3) An indistinct procedure is clarified and procedure of water quality analysis was established in the HTTR. (4) It is assumed that the corrosion of the components in these water cooling system hardly occurred from measurement results of dissolved oxide and chloride ion. Thus, the water quality was managed enough.

JAEA Reports

Countermeasure to prevent residence nitrogen gas in Pressurized Water Cooling System

Furusawa, Takayuki; Saikusa, Akio; Hamamoto, Shimpei; Nemoto, Takahiro; Shinohara, Masanori; Isozaki, Minoru

JAEA-Technology 2007-066, 38 Pages, 2008/01

JAEA-Technology-2007-066.pdf:15.66MB

In the HTTR rise-to-power test which was performed from April in 2000 as phase 1 up to 10MW, nitrogen gas remained in the air cooler which release the heat to atmosphere. This residence nitrogen gas causes the reduction of the thermal performance of the air cooler. So, it was impossible that heat generated reactor core could not remove when reactor operated full power operation. A mockup test was carried out to investigate the occurrence mechanism of the residence nitrogen gas. From a result of the mockup test, we clarified that the marked wave rise in the water pressurizer and the melting velocity of the nitrogen gas into the pressurized water is thought to be higher than expected. Therefore, we installed a hollow type plate, multi-hole type plate and so on in the water pressurizer. As a result, it was confirmed that no residence nitrogen gas in the air cooler during rise-to-power test and normal operation. Consequently, the hollow type plate and multi-hole type plate were effective for prevention of the residence nitrogen gas in the air cooler. This paper describes the results of the mockup test and the improvement of the water pressurizer.

Journal Articles

Heat exchanger performance in main cooling system on high temperature test operation at High Temperature Gas-Cooled Reactor 'HTTR'

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 950$$^{circ}$$C 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.

Journal Articles

Coolant chemistry of the High Temperature Gas-Cooled Reactor '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.

Journal Articles

Short design descriptions of other systems of the HTTR

Sakaba, Nariaki; Furusawa, Takayuki; Kawamoto, Taiki; Ishii, Yoshiki; Ota, Yukimaru

Nuclear Engineering and Design, 233(1-3), p.147 - 154, 2004/10

 Times Cited Count:10 Percentile:58.07(Nuclear Science & Technology)

The HTTR mainly consists of the core components, reactor pressure vessel, cooling systems, instrumentation and control systems, and containment structures. The design of remaining utility systems is described in this paper. They are: auxiliary helium systems which include the helium purification system, the helium sampling system, and the helium storage and supply system; fuel handling and storage system. The helium purification systems are installed in the primary and secondary helium cooling systems in order to reduce the quantity of chemical impurities. The helium sampling systems monitor the concentration of impurities. The helium storage and supply systems keep the steady pressure of the helium system during the normal operation. The fuel handling and storage system is utilised to handle the new and spent fuels safely and reliably.

Journal Articles

Temperature transient analysis of gas circulator trip test using the HTTR

Takamatsu, Kuniyoshi; Furusawa, Takayuki; Hamamoto, Shimpei; Nakagawa, Shigeaki

Proceedings of 6th International Topical Meeting on Nuclear Reactor Thermal Hydraulics, Operations and Safety (NUTHOS-6) (CD-ROM), 11 Pages, 2004/10

Safety demonstration tests using the High Temperature Engineering Test Reactor (HTTR) are in progress to verify the inherent safety features for High Temperature Gas-cooled Reactors (HTGRs). The coolant flow reduction test by tripping one or two out of three gas circulators is one of the safety demonstration tests. The reactor power safely brings to a stable level without a reactor scram and the temperature transient of the reactor-core is very slow. Through the safety demonstration test, the two dimensional temperature analysis code (TAC-NC code) was improved. This paper describes the validation of the TAC-NC code using the measured value of the test by tripping of one and two out of three gas circulators at 30%(9MW). The TAC-NC code could evaluate accurately the temperature transient within 10% during the test. Also, it was confirmed that the temperature transient by tripping all gas circulators is very slow.

JAEA Reports

Structural integrity assessment of helium component during safety demonstration test using HTTR, 1 (Contract Research)

Sakaba, Nariaki; Nakagawa, Shigeaki; Furusawa, Takayuki; Tachibana, Yukio

JAERI-Tech 2004-045, 67 Pages, 2004/04

JAERI-Tech-2004-045.pdf:4.74MB

Safety demonstration tests using the HTTR are now underway in order to verify the inherent safety features and to improve the safety design and evaluation technologies for HTGRs, as well as to contribute to research and development for the VHTR, which is one of the Generation IV reactors. In the safety demonstration tests, the coolant flow reduction test by tripping one or two out of three gas circulators is being performed between FY2002 and FY 2005 and by tripping all the three gas circulators will be conducted after FY2006. This paper describes the structural integrity assessment of the primary pressurised water cooler after one and two gas circulators run down. Also, the possibility of natural convection in the primary coolant after all the three gas circulator stopped was evaluated by the operation data of the reactor-scram test performed during the rise-to-power tests.

JAEA Reports

Replacement of the filter for primary helium circulators of the HTTR

Furusawa, Takayuki; Sumita, Junya; Ueta, Shohei; Nemoto, Takahiro; Oyama, Sunao*; Kamata, Takashi

JAERI-Tech 2004-024, 46 Pages, 2004/03

JAERI-Tech-2004-024.pdf:6.75MB

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.

36 (Records 1-20 displayed on this page)