Refine your search:     
Report No.
 - 
Search Results: Records 1-20 displayed on this page of 124

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

Post irradiation experiment about SiC-coated oxidation-resistant graphite for high temperature gas-cooled reactor

Shibata, Taiju; Mizuta, Naoki; Sumita, Junya; Sakaba, Nariaki; Osaki, Takashi*; Kato, Hideki*; Izawa, Shoichi*; Muto, Takenori*; Gizatulin, S.*; Shaimerdenov, A.*; et al.

Proceedings of 9th International Topical Meeting on High Temperature Reactor Technology (HTR 2018) (USB Flash Drive), 7 Pages, 2018/10

Graphite materials are used for the in-core components of High Temperature Gas-cooled Reactor (HTGR). Oxidation damage on the graphite components in air ingress accident is a crucial issue for the safety point of view. SiC coating on graphite surface is a possible technique to enhance oxidation resistance. However, it is important to confirm the integrity of this material against high temperature and neutron irradiation for the application of the in-core components. JAEA and Japanese graphite companies carried out the R&D to develop the oxidation-resistant graphite. JAEA and INP investigated the irradiation effects on the oxidation-resistant graphite by using a framework of ISTC partner project. This paper describes the results of post irradiation experiment about the neutron irradiated SiC-coated oxidation-resistant graphite. A brand of oxidation-resistant graphite shows excellent performance against oxidation test after the irradiation.

Journal Articles

RELAP5 modeling of the HTTR-GT/H$$_{2}$$ secondary system and turbomachinery

Humrickhouse, P. W.*; Sato, Hiroyuki; Imai, Yoshiyuki; Sumita, Junya; Yan, X. L.

Proceedings of 9th International Topical Meeting on High Temperature Reactor Technology (HTR 2018) (USB Flash Drive), 9 Pages, 2018/10

This work describes the development of a RELAP5-3D model of the HTTR-GT/H$$_{2}$$ plant secondary system. The RELAP5-3D model presently includes detailed models of several of the heat exchangers in the secondary system as well as the turbomachinery, which includes two compressors and two gas turbines connected to a common shaft and motor. The predictions of the model agreed well to design parameters in both sole power generation and hydrogen co-generation modes in most instances. Both the turbomachinery and heat exchanger models rely on extensive customization via RELAP5-3D control variables, and these implementations are outlined in detail. Potential improvements to the RELAP5-3D turbine model are discussed.

Journal Articles

Enhancement of oxidation tolerance of graphite materials for high temperature gas-cooled reactor

Mizuta, Naoki; Sumita, Junya; Shibata, Taiju; Osaki, Takashi*; Kato, Hideki*; Izawa, Shoichi*; Muto, Takenori*; Gizatulin, S.*; Sakaba, Nariaki

Tanso Zairyo Kagaku No Shinten; Nihon Gakutsu Shinkokai Dai-117-Iinkai 70-Shunen Kinen-Shi, p.161 - 166, 2018/10

To enhance oxidation resistance of graphite material for in-core components of HTGR, JAEA and four Japanese graphite companies; Toyo Tanso, IBIDEN, Tokai Carbon and Nippon Techno-Carbon, are carrying out for development of oxidation-resistant graphite by CVD-SiC coating. This paper describes the outline of neutron irradiation test about the oxidation-resistant graphite by WWR-K reactor of INP, Kazakhstan through an ISTC partner project. Prior to the irradiation test, the oxidation-resistant graphite by CVD-SiC coating of all specimens showed enough oxidation resistance under un-irradiation condition. The neutron irradiation test was already completed and out-of-pile oxidation test will be carried out at the hot-laboratory of WWR-K.

Journal Articles

HTTR-GT/H$$_{2}$$ test plant; System performance evaluation for HTTR gas turbine cogeneration plant

Sato, Hiroyuki; Nomoto, Yasunobu*; Horii, Shoichi*; Sumita, Junya; Yan, X.

Nuclear Engineering and Design, 329, p.247 - 254, 2018/04

 Times Cited Count:3 Percentile:57.14(Nuclear Science & Technology)

This paper presents the system performance evaluation for HTTR gas turbine cogeneration test plant (HTTR-GT/H$$_{2}$$ plant) so as to confirm that the design meets the requirements with respect to the demonstration test objective. Start-up and shut down operation sequences as well as operability of load following operation were investigated. In addition, system dynamic and control analyses for the test plant in the events of loss of generator load and upset of H$$_{2}$$ plant were performed. The simulation results presented in the paper show that the test plant is suitable for the test bed to validate control schemes against postulated transients in the GTHTR300C. The results also lead us to the conclusion that HTTR-GT/H$$_{2}$$ plant can be used to test operational procedures unique to HTGR direct-cycle gas turbine cogeneration.

Journal Articles

Design of HTTR-GT/H$$_{2}$$ test plant

Yan, X. L.; Sato, Hiroyuki; Sumita, Junya; Nomoto, Yasunobu*; Horii, Shoichi*; Imai, Yoshiyuki; Kasahara, Seiji; Suzuki, Koichi*; Iwatsuki, Jin; Terada, Atsuhiko; et al.

Nuclear Engineering and Design, 329, p.223 - 233, 2018/04

 Times Cited Count:6 Percentile:17.69(Nuclear Science & Technology)

The pre-licensing design of an HTGR cogeneration test plant to be coupled to JAEA's existing test reactor HTTR is presented. The plant is designed to demonstrate the system of JAEA commercial plant design GTHTR300C. With construction planned to be completed around 2025, the test plant is expected to be the first-of-a-kind nuclear system operating on two of the advanced energy conversion systems attractive for the HTGR closed cycle helium gas turbine for power generation and thermochemical iodine-sulfur water-splitting process for hydrogen production.

Journal Articles

Cost performance design for high temperature helium heat transport piping of GTHTR300C and HTTR-GT/H $$_{2}$$ plants

Nomoto, Yasunobu; Horii, Shoichi; Sumita, Junya; Sato, Hiroyuki; Yan, X.

Proceedings of 2017 International Congress on Advances in Nuclear Power Plants (ICAPP 2017) (CD-ROM), 9 Pages, 2017/04

This paper presents the cost performance design of heat transport piping systems for GTHTR300C plant and HTTR-GT/H $$_{2}$$ plant. Two types of pipe structure are designed and compared in terms of cost performance. Relative to the coaxial double-pipe structure, the insulated single pipe structure is found to have the advantage in overall cost performance considering both the material quantity and the heat loss because it reduces the quantity of steel used for construction. Furthermore it is possible to reduce the heat loss and temperature reduction of hot helium gas by the attachment of the external insulation. The pressure tube made of type-316 stainless steel with high-temperature strength is possible to achieve the same temperature reduction by smaller diameter than that made of 2 1/4Cr-1Mo steel. It contributes to the reduction of the quantity of steel. Specifications of heat transport piping systems for both plants are determined according to these study results.

Journal Articles

Nuclear thermal design of high temperature gas-cooled reactor with SiC/C mixed matrix fuel compacts

Aihara, Jun; Goto, Minoru; Inaba, Yoshitomo; Ueta, Shohei; Sumita, Junya; Tachibana, Yukio

Proceedings of 8th International Topical Meeting on High Temperature Reactor Technology (HTR 2016) (CD-ROM), p.814 - 822, 2016/11

Japan Atomic Energy Agency (JAEA) has started R&D for apply SiC/C mixed matrix to fuel element of high temperature gas-cooled reactors (HTGRs) to improve oxidation resistance of fuel. Nuclear thermal design of HTGR with SiC/C mixed matrix fuel compacts was carried out as a part of above R&Ds. Nuclear thermal design was carried out based on a small sized HTGR for developing countries, HTR50S. Maximum enrichment of uranium is set to be 10 wt%, because coated fuel particles with 10 wt% uranium have been fabricated in Japan. Numbers of kinds of enrichment and burnable poisons (BPs) were set to be same as those of original HTR50S (3 and 2, respectively). We succeeded in nuclear thermal design of a small sized HTGR which performance was equivalent to original HTR50S, with SiC/C mixed matrix fuel compacts. Based on nuclear thermal design, intactness of coated fuel particles was evaluated to be kept on internal pressure during normal operation.

Journal Articles

HTTR-GT/H$$_{2}$$ test plant; System performance evaluation for HTTR gas turbine cogeneration plant

Sato, Hiroyuki; Nomoto, Yasunobu; Horii, Shoichi; Sumita, Junya; Yan, X.; Ohashi, Hirofumi

Proceedings of 8th International Topical Meeting on High Temperature Reactor Technology (HTR 2016) (CD-ROM), p.759 - 766, 2016/11

This paper presents the system performance evaluation for HTTR gas turbine cogeneration test plant (HTTR-GT/H$$_{2}$$ plant) so as to confirm that the design meets the requirements with respect to the demonstration test objective. Start-up and shut down operation sequences as well as operability of load following operation were investigated. In addition, system dynamic and control analyses for the test plant in the events of loss of generator load and upset of H$$_{2}$$ plant were performed. The simulation results presented in the paper show that the test plant is suitable for the test bed to validate control schemes against postulated transients in the commercial Gas Turbine High Temperature Reactor Cogeneration (GTHTR300C). The results also lead us to the conclusion that HTTR-GT/H$$_{2}$$ plant can be used to test operational procedure unique to HTGR direct-cycle gas turbine cogeneration.

Journal Articles

Irradiation test about oxidation-resistant graphite in WWR-K research reactor

Shibata, Taiju; Sumita, Junya; Sakaba, Nariaki; Osaki, Takashi*; Kato, Hideki*; Izawa, Shoichi*; Muto, Takenori*; Gizatulin, S.*; Shaimerdenov, A.*; Dyussambayev, D.*; et al.

Proceedings of 8th International Topical Meeting on High Temperature Reactor Technology (HTR 2016) (CD-ROM), p.567 - 571, 2016/11

Graphite are used for the in-core components of HTGR, and it is desirable to enhance oxidation resistance to keep much safety margin. SiC coating is the candidate method for this purpose. JAEA and four Japanese graphite companies are studying to develop oxidation-resistant graphite. Neutron irradiation test was carried out by WWR-K reactor of INP of Kazakhstan through ISTC partner project. The total irradiation cycles of WWR-K operation was 10 cycles by 200 days. Irradiation temperature about 1473 K would be attained. The maximum fast neutron fluence (E $$>$$0.18 MeV) for the capsule irradiated at a central irradiation hole was preliminary calculated as 1.2$$times$$10$$^{25}$$/m$$^{-2}$$, and for the capsule at a peripheral irradiation hole as 4.2$$times$$10$$^{24}$$/m$$^{-2}$$. Dimension and weight of the irradiated specimens were measured, and outer surface of the specimens were observed by optical microscope. For the irradiated oxidation resistant graphite, out-of-pile oxidation test will be carried out at an experimental laboratory.

Journal Articles

Corrosion test of HTGR graphite with SiC coating

Chikhray, Y.*; Kulsartov, T.*; Shestakov, V.*; Kenzhina, I.*; Askerbekov, S.*; Sumita, Junya; Ueta, Shohei; Shibata, Taiju; Sakaba, Nariaki; Abdullin, Kh.*; et al.

Proceedings of 8th International Topical Meeting on High Temperature Reactor Technology (HTR 2016) (CD-ROM), p.572 - 577, 2016/11

Application of SiC as corrosion-resistive coating over graphite remains important task for HTGR. This study presents the results of chemical interaction of the SiC gradient coating over the high-density IG-110 graphite with water vapor in the temperature up to 1673 K. The experiments at 100 Pa of water vapor showed that the passive reaction caused to form SiO$$_{2}$$ film on the surface of SiC coating. Active corrosion of SiC in 1Pa of water vapor leads to deposits of various carbon composites on its surface.

Journal Articles

HTTR-GT/H$$_{2}$$ test plant; System design

Yan, X.; Sato, Hiroyuki; Sumita, Junya; Nomoto, Yasunobu; Horii, Shoichi; Imai, Yoshiyuki; Kasahara, Seiji; Suzuki, Koichi*; Iwatsuki, Jin; Terada, Atsuhiko; et al.

Proceedings of 8th International Topical Meeting on High Temperature Reactor Technology (HTR 2016) (CD-ROM), p.827 - 836, 2016/11

Pre-licensing basic design for a cogenerating HTGR test plant system is presented. The plant to be coupled to existing 30 MWt 950$$^{circ}$$C test reactor HTTR is intended as a system technology demonstrator for GTHTR300C plant design. More specifically the test plant of HTTR-GT/H$$_{2}$$ aims to (1)demonstrate the licensability of the GTHTR300C for electricity production by gas turbine and hydrogen cogeneration by thermochemical process and (2) confirm the operation control and safety of such cogeneration system. With construction and operation completion by 2025, the test plant is expected to be the first of a kind HTGR-powered cogeneration plant operating on the two advanced energy conversion systems of closed cycle helium gas turbine for power generation and thermochemical iodine-sulfur water-splitting process for hydrogen production.

Journal Articles

HTTR demonstration program for nuclear cogeneration of hydrogen and electricity

Sato, Hiroyuki; Yan, X.; Sumita, Junya; Terada, Atsuhiko; Tachibana, Yukio

Journal of Nuclear Engineering and Radiation Science, 2(3), p.031010_1 - 031010_6, 2016/07

This paper explains the outline of HTTR demonstration program with a plant concept of the heat application system directed at establishing an HTGR cogeneration system with 950$$^{circ}$$C reactor outlet temperature for production of power and hydrogen as recommended by the task force. Commercial deployment strategy including a development plan for the helium gas turbine is also presented.

Journal Articles

Automated control for electric-thermal load following operation in nuclear gas turbine cogeneration system

Sato, Hiroyuki; Yan, X.; Sumita, Junya; Terada, Atsuhiko; Nishihara, Tetsuo

Proceedings of International Gas Turbine Congress 2015 (IGTC 2015) (DVD-ROM), p.184 - 190, 2015/11

This paper presents the original control system design to provide for an extended range of electrical-thermal load-following in the GTHTR300. The turbine speed control is newly added to the basic plant control to take full advantage of the system characteristics of the HTGR and the closed-cycle gas turbine to accomplish the design goal of maintaining constant reactor power and high thermal efficiency during the load-following operation. Simulation result presented in the paper shows that the design goal can be effectively met. The paper also describes a demonstration program to validate the system operability by connecting an electricity and hydrogen cogeneration plant to the HTTR.

Journal Articles

HTTR demonstration program for nuclear cogeneration of hydrogen and electricity

Sato, Hiroyuki; Sumita, Junya; Terada, Atsuhiko; Ohashi, Hirofumi; Yan, X.; Nishihara, Tetsuo; Tachibana, Yukio; Inagaki, Yoshiyuki

Proceedings of 23rd International Conference on Nuclear Engineering (ICONE-23) (DVD-ROM), 8 Pages, 2015/05

This paper explains the outline and schedule of HTTR demonstration program with a plant concept of the heat application system directed at establishing an HTGR cogeneration system with 950$$^{circ}$$C reactor outlet temperature for production of power and hydrogen as recommended by the task force.

Journal Articles

Applicability study of nuclear graphite material IG-430 to VHTR

Osaki, Hirotaka; Shimazaki, Yosuke; Sumita, Junya; Shibata, Taiju; Konishi, Takashi; Ishihara, Masahiro

Proceedings of 23rd International Conference on Nuclear Engineering (ICONE-23) (DVD-ROM), 8 Pages, 2015/05

For the design on the VHTR graphite components, it is desirable to employ graphite material with higher strength. IG-430 graphite has been developed as an advanced candidate for VHTR. However, the new developed IG-430 does not have enough databases for the design of HTGR. In this paper, the compressive strength (Cs) of IG-430, one of important strengths for design data, is statistically evaluated. The component reliability is evaluated based on the safety factors defined by the graphite design code, and the applicability as the VHTR graphite material is discussed. It was found that IG-430 has higher strength (about 11%) and lower standard deviation (about 27%) than IG-110 which is one of traditional graphites used for HTGR, because the crack in IG-430 would not easy to propagate rather than IG-110. Since fracture probability for IG-430 is low, the higher reliability of core-component will be achieved using IG-430. It is expected that IG-430 is applicable for VHTR graphite material.

Journal Articles

Investigation on structural integrity of graphite component during high temperature 950$$^{circ}$$C continuous operation of HTTR

Sumita, Junya; Shimazaki, Yosuke; Shibata, Taiju

Journal of Nuclear Science and Technology, 51(11-12), p.1364 - 1372, 2014/11

 Times Cited Count:5 Percentile:60.19(Nuclear Science & Technology)

Graphite material is used for internal structures in High Temperature Gas-cooled Reactor (HTGR). The core components and graphite core support structures are so designed as to maintain the structural integrity to keep core cooling capability. In order to confirm that the core components and graphite core support structures satisfy the design requirement, the temperatures of the reactor internals are measured during the reactor operation. Surveillance test of graphite specimens and in-service inspection (ISI) using TV camera are planned in conjunction with the refueling. This paper describes the evaluation results of the integrity of the core components and graphite core support structures during the high temperature 950$$^{circ}$$C continuous operation, reactor outlet temperature of 950$$^{circ}$$C for 50 days, in HTTR (High Temperature Engineering Test Reactor). The design requirements of the core components and graphite core support structure were satisfied during the high temperature 950$$^{circ}$$C continuous operation. The dimensional change of graphite which directly influences the temperature of coolant was evaluated with considering the temperature profiles of fuel block. The magnitude of irradiation-induced dimensional change was about 1.2 times larger than that of isotherm for 1000$$^{circ}$$C. In addition, the programs of surveillance test and ISI using TV camera were introduced.

Journal Articles

Irradiation test plan of oxidation-resistant graphite in WWR-K research reactor

Sumita, Junya; Shibata, Taiju; Sakaba, Nariaki; Osaki, Hiroki*; Kato, Hideki*; Fujitsuka, Kunihiro*; Muto, Takenori*; Gizatulin, S.*; Shaimerdenov, A.*; Dyussambayev, D.*; et al.

Proceedings of 7th International Topical Meeting on High Temperature Reactor Technology (HTR 2014) (USB Flash Drive), 7 Pages, 2014/10

Graphite materials are used for the in-core components of High Temperature Gas-cooled Reactor(HTGR)which is a graphite-moderated and helium gas-cooled reactor. In the case of air ingress accident in HTGR, SiO$$_{2}$$ protective layer is formed on the surface of SiC layer in TRISO CFP and oxidation of SiC does not proceed and fission products are retained inside the fuel particle. A new safety concept for the HTGR, called Naturally Safe HTGR, has been recently proposed. To enhance the safety of Naturally Safe HTGR ultimately, it is expected that oxidation-resistant graphite is used for graphite components to prevent the TRISO CFPs and fuel compacts from failure. SiC coating is one of candidate methods for oxidation-resistant graphite. JAEA and four graphite companies launched R&Ds to develop the oxidation-resistant graphite and the International Science and Technology Center(ISTC) partner project with JAEA and INP was launched to investigate the irradiation effects on the oxidation-resistant graphite. To determine grades of the oxidation-resistant graphite which will be adopted as irradiation test, a preliminary oxidation test was carried out. This paper described the results of the preliminary oxidation test, the plan of out-of-pile test, irradiation test and post-irradiation test(PIE)of the oxidation-resistant graphite.

Journal Articles

R&D plan for development of oxidation-resistant graphite and investigation of oxidation behavior of SiC coated fuel particle to enhance safety of HTGR

Ueta, Shohei; Sumita, Junya; Shibata, Taiju; Aihara, Jun; Fujita, Ichiro*; Ohashi, Jun*; Nagaishi, Yoshihide*; Muto, Takenori*; Sawa, Kazuhiro; Sakaba, Nariaki

Nuclear Engineering and Design, 271, p.309 - 313, 2014/05

 Times Cited Count:7 Percentile:40.08(Nuclear Science & Technology)

A new concept of the high temperature gas-cooled reactor (HTGR) is proposed as a challenge to assure no event sequences to the harmful release of radioactive materials even when the design extension conditions (DECs) occur by deterministic approach based on the inherent safety features of the HTGR. The air/water ingress accident, one of the DECs for the HTGR, is prevented by additional measures (e.g. facility for suppression to air ingress). With regard to the core design, it is important to prevent recriticality accidents by keeping the geometry of the fuel rod which consists of the graphite sleeve, fuel compact and SiC-TRISO (TRIstructural-ISOtropic) coated fuel particle, and by improving the oxidation resistance of the graphite when air/water ingress accidents occur. Therefore, it is planned to develop the oxidation-resistant graphite, which is coated with gradient SiC layer. It is also planned that the experimental identification of the condition to form the stable oxide layer (SiO$$_{2}$$) for SiC layer on the oxidation-resistant graphite and on the SiC-TRISO fuel. This paper describes the R&D plan for un-irradiation and irradiation test under simulating air/water ingress accident condition to develop oxidation-resistant graphite and to investigate the oxidation behavior of SiC coated fuel particle.

Journal Articles

Development of evaluation method with X-ray tomography for material property of IG-430 graphite for VHTR/HTGR

Sumita, Junya; Shibata, Taiju; Fujita, Ichiro*; Kunimoto, Eiji*; Yamaji, Masatoshi*; Eto, Motokuni*; Konishi, Takashi*; Sawa, Kazuhiro

Nuclear Engineering and Design, 271, p.314 - 317, 2014/05

 Times Cited Count:6 Percentile:46.09(Nuclear Science & Technology)

In this study, in order to develop evaluation method for material properties and to evaluate the irradiation-induced property changes under higher neutron doses for IG-430, the oxidation and densification effects on elastic modulus of IG-430 were investigated. Moreover, the correlation of the microstructure based on the X-ray tomography images and the material properties was discussed. It was shown that the elastic modulus of the densified graphite depends on only the closed pores and it is possible to evaluate the material properties of graphite by using X-ray tomography method. However, it is necessary to take into account of the change in the number and shape of closed pores in the grain to simulate the elastic modulus of the highly oxidized and irradiated materials by the homogenization analysis.

Journal Articles

Evaluation of fracture toughness of fine-grained isotropic graphites for HTGR

Yamada, Teruaki*; Matsushima, Yuki*; Kuroda, Masatoshi*; Sumita, Junya; Shibata, Taiju; Fujita, Ichiro*; Sawa, Kazuhiro

Nuclear Engineering and Design, 271, p.323 - 326, 2014/05

 Times Cited Count:4 Percentile:78.23(Nuclear Science & Technology)

In order to investigate the effects of the experimental methodology and the notch angle on the fracture toughness of the fine-grained isotropic nuclear graphites IG-110 and IG-430, the three-point-bending test, which has been recently proposed as the methodology to evaluate the fracture toughness of graphite for high temperature gas-cooled reactors (HTGRs), was performed using two types of the specimens with different notch angles. The results obtained in this study could be summarized as follows: (1) The values of the fracture toughness of IG-110 and IG-430 measured in this study were 0.890 MPa m$$^{1/2}$$ and 1.031 MPa m$$^{1/2}$$, respectively. It was also found that the value of the fracture toughness of IG-110 was nearly equal to or smaller than the values obtained by the other method reported previously. (2) The values of the fracture toughness of the fine-grained isotropic graphites were not affected between the notch angles introduced by the incisive razor blade. (3) The ratio of the tensile strengths of IG-110 and IG-430 was estimated from Griffith Theory using the experimental data obtained in this study. The estimated strength ratio was in good agreement with the strength ratio obtained from the supplier's data.

124 (Records 1-20 displayed on this page)