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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.

JAEA Reports

Prototype fast breeder reactor Monju; Its history and achievements (Translated document)

Mitsumoto, Rika; Hazama, Taira; Takahashi, Keita; Kondo, Satoru

JAEA-Technology 2019-020, 167 Pages, 2020/03


The prototype fast breeder reactor Monju has produced valuable technological achievements through design, construction, operation and maintenance over half a century since 1968. This report compiles the reactor technologies developed for Monju, including the areas: history and major achievements, design and construction, commissioning, safety, reactor physics, fuel, systems and components, sodium technology, materials and structures, operation and maintenance, and accidents and failures.

JAEA Reports

Phase 1 code assessment of SIMMER-III; A Computer program for LMFR core disruptive accident analysis

Kondo, Satoru; Tobita, Yoshiharu

JAEA-Research 2019-009, 382 Pages, 2020/03


The SIMMER-III computer code, developed at the Japan Atomic Energy Agency (JAEA, the former Power Reactor and Nuclear Fuel Development Corporation), is a two-dimensional, multi-velocity-field, multi-component fluid-dynamics code, coupled with a space- and time-dependent neutron kinetics model. The code is being used widely for simulating complex phenomena during core-disruptive accidents (CDAs) in liquid-metal fast reactors (LMFRs). In parallel to the code development, a comprehensive assessment program was performed in two phases: Phase 1 for verifying individual fluid-dynamics models; and Phase 2 for validating its applicability to integral phenomena important to evaluating LMFR CDAs. The SIMMERIII assessment program was participated by European research and development organizations, and the achievement of Phase 1 was compiled and synthesized in 1996. This report has been edited by revising and reproducing the original 1996 informal report, which compiled the achievement of Phase 1 assessment. A total of 34 test problems were studied in the areas: fluid convection, interfacial area and momentum exchange, heat transfer, melting and freezing, and vaporization and condensation. The problems identified have been reflected to the Phase 2 assessment and later model development and improvement. Although the revisions were made in the light of knowledge base obtained later, the original individual contributions by the participants, both positive and negative, are retained except for editorial changes.

Journal Articles

In-beam $$gamma$$-ray spectroscopy of $$^{35}$$Mg via knockout reactions at intermediate energies

Momiyama, Satoru*; Doornenbal, P.*; Scheit, H.*; Takeuchi, Satoshi*; Niikura, Megumi*; Aoi, Nori*; Li, K.*; Matsushita, Masafumi*; Steppenbeck, D.*; Wang, H.*; et al.

Physical Review C, 96(3), p.034328_1 - 034328_8, 2017/09

 Times Cited Count:6 Percentile:53.24(Physics, Nuclear)

no abstracts in English

Journal Articles

X-ray absorption spectroscopy in the heavy Fermion compound $$alpha$$-YbAlB$$_4$$ at high magnetic fields

Terashima, Taku*; Matsuda, Yasuhiro*; Kuga, Kentaro*; Suzuki, Shintaro*; Matsumoto, Yosuke*; Nakatsuji, Satoru*; Kondo, Akihiro*; Kindo, Koichi*; Kawamura, Naomi*; Mizumaki, Masaichiro*; et al.

Journal of the Physical Society of Japan, 84(11), p.114715_1 - 114715_4, 2015/11

 Times Cited Count:3 Percentile:30.97(Physics, Multidisciplinary)

Journal Articles

Safety requirements expected for the prototype fast breeder reactor "Monju"

Saito, Shinzo; Okamoto, Koji*; Kataoka, Isao*; Sugiyama, Kenichiro*; Muramatsu, Ken*; Ichimiya, Masakazu*; Kondo, Satoru; Yonomoto, Taisuke

Proceedings of 23rd International Conference on Nuclear Engineering (ICONE-23) (DVD-ROM), 10 Pages, 2015/05

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


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

Synchrotron X-ray spectroscopy study on the valence state and magnetization in $$alpha$$-YbAl$$_{1-x}$$Fe$$_x$$B$$_4$$ ($$x=0.115$$) at low temperatures and high magnetic fields

Terashima, Taku*; Matsuda, Yasuhiro*; Kuga, Kentaro*; Suzuki, Shintaro*; Matsumoto, Yosuke*; Nakatsuji, Satoru*; Kondo, Akihiro*; Kindo, Koichi*; Kawamura, Naomi*; Mizumaki, Masaichiro*; et al.

Journal of Physics; Conference Series, 592(1), p.012020_1 - 012020_6, 2015/03

 Times Cited Count:1 Percentile:45.56

Valence fluctuation phenomena in rare-earth intermetallic compounds have attracted attention because the quantum criticality of the valence transition has been proposed theoretically. Recently, it was found that $$beta$$-YbAlB$$_4$$ shows quantum criticality without tuning and has a strong mixed-valence state. In this study, we measured the magnetization curve and X-ray magnetoabsorption in $$alpha$$-YbAl$$_{1-x}$$Fe$$_x$$B$$_4$$ ($$x=0.115$$), which is a locally isostructural polymorph of $$beta$$-YbAlB$$_4$$. The magnetization and X-ray experiments were performed in fields up to 55 and 40 T, respectively. A small increase in the Yb valence was observed at fields where the magnetization curve exhibited a change in slope.

Journal Articles

Recent progress and status of Monju

Kondo, Satoru; Deshimaru, Takehide; Konomura, Mamoru

Proceedings of International Conference on Fast Reactors and Related Fuel Cycles; Safe Technologies and Sustainable Scenarios (FR-13) (USB Flash Drive), 6 Pages, 2013/03

Monju, a 280-MWe prototype sodium-cooled fast reactor of, restarted its test operation in 2010. The zero-power tests were successfully conducted. It's major achievement was accurate prediction of reactor physics parameters with a core including americium-rich fuel. The reactor, however, has been put into a stand-by mode again since the 3.11 Fukushima-Daiichi accident. The roles shall not change: demonstrating stable power generation and actinide burning; providing technology and knowledge base for future SFRs; and using the plant as an international research facility.

Journal Articles

In situ electrochemical, electrochemical quartz crystal microbalance, scanning tunneling microscopy, and surface X-ray scattering studies on Ag/AgCl reaction at the underpotentially deposited Ag bilayer on the Au(111) electrode surface

Uosaki, Kohei*; Morita, Jun*; Katsuzaki, Tomoko*; Takakusagi, Satoru*; Tamura, Kazuhisa; Takahashi, Masamitsu; Mizuki, Junichiro; Kondo, Toshihiro*

Journal of Physical Chemistry C, 115(25), p.12471 - 12482, 2011/06

 Times Cited Count:12 Percentile:40.41(Chemistry, Physical)

Ag/AgCl reaction at the Ag bilayer, which was underpotentially prepared on a Au(111) surface, was investigated using electrochemical quartz crystal microbalance (EQCM), scanning tunneling microscopy (STM), surface X-ray scattering (SXS), and electrochemical techniques. When the potential was scanned positively from -200 mV, the Cl$$^{-}$$ ion was adsorbed on the Au(111) electrode surface around 0 mV, and then the phase transition of the adsorbed Cl$$^{-}$$ ion layer from random orientation to ($$sqrt{3}$$ $$times$$ $$sqrt{3}$$) structure took place at around +130 mV. The Ag bilayer and Cl$$^{-}$$ ions were oxidatively reacted to form the AgCl monolayer with ($$sqrt{13}$$ $$times$$ $$sqrt{13}$$) $$R$$13.9$$^{circ}$$ structure around +200 mV, accompanied with the formation of AgCl monocrystalline clusters on the AgCl monolayer surface. The structure of the AgCl monolayer on the Au(111) surface was changed from ($$sqrt{13}$$ $$times$$ $$sqrt{13}$$)R13.9$$^{circ}$$ structure to (4$$times$$4) structure around +500 mV.

Journal Articles

Partial stripping of Ag atoms from silver bilayer on a Au(111) surface accompanied with the reductive desorption of hexanethiol SAM

Kondo, Toshihiro*; Tamura, Kazuhisa; Takakusagi, Satoru*; Kitamura, Ken*; Takahashi, Masamitsu; Mizuki, Junichiro; Uosaki, Kohei*

Journal of Solid State Electrochemistry, 13(7), p.1141 - 1145, 2009/07

 Times Cited Count:5 Percentile:13.73(Electrochemistry)

The interfacial structures of Ag bilayer prepared by underpotential deposition on Au(111) were determined by STM and SXS before and after oxidative adsorption and after desorption of a SAM of C$$_{6}$$SH in alkaline ethanol solution. While no structural change was observed after oxidative formation of C$$_{6}$$SH SAM on the Ag/Au(111) in an ethanol solution containing 20 mM KOH and 0.1 mM C$$_{6}$$SH, some of the Ag atoms in the bilayer were stripped when the SAM was reductively desorbed.

Journal Articles

Latest design of liquid lithium target in IFMIF

Nakamura, Hiroo; Agostini, P.*; Ara, Kuniaki; Cevolani, S.*; Chida, Teruo*; Ciotti, M.*; Fukada, Satoshi*; Furuya, Kazuyuki*; Garin, P.*; Gessii, A.*; et al.

Fusion Engineering and Design, 83(7-9), p.1007 - 1014, 2008/12

 Times Cited Count:15 Percentile:70.93(Nuclear Science & Technology)

This paper describes the latest design of liquid lithium target system in IFMIF. Design requirement of the Li target is to provide a stable Li jet with a speed of 20 m/s to handle an averaged heat flux of 1 GW/m$$^{2}$$. A double reducer nozzle and a concaved flow are applied to the target design. On Li purification, a cold trap and two kinds of hot trap are applied to control impurities below permissible levels. Nitrogen concentration shall be controlled below 10 wppm by one of the hot trap. Tritium concentration shall be controlled below 1 wppm by an yttrium hot trap. To maintain reliable continuous operation, various diagnostics are attached to the target assembly. Among the target assembly, a back-plate made of RAFM is located in the most severe region of neutron irradiation (50 dpa/y). Therefore, two design options of replaceable back wall and their remote handling systems are under investigation.

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


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.

Journal Articles

Japanese fast reactor program for homogeneous actinide recycling

Ishikawa, Makoto; Nagata, Takashi; Kondo, Satoru

Proceedings of International Conference on the Physics of Reactors, Nuclear Power; A Sustainable Resource (PHYSOR 2008) (CD-ROM), 8 Pages, 2008/09

In Japan, the significance of the development of fast reactor (FR) cycle technology has been seriously recognized in the national fundamental nuclear energy policy. Further, nuclear energy as a whole is indispensable worldwide to meet the expansion of energy demand and the solution of environmental problem such as global climate change. Under such circumstances, Japan launched the FR Cycle Technology Development (FaCT) Project in 2006. In FaCT, the design study and the R&D on innovative technologies regarding the main concept are conducted in order to present the conceptual designs of demonstration and commercial FR cycle facilities by around 2015. The main purpose of the near-term R&Ds by 2010 is to judge whether adoption of innovative technologies is feasible. The R&D program on the innovative technologies will be further extended toward 2015, with the demonstration FR expected to be operated in 2025. The concept of the FR cycle system has various aspects from the viewpoints of safety and reliability, economy, sustainability (consisting of reduction of environmental burden, waste management and efficient utilization of uranium resource), and proliferation resistance. The homogeneous recycling of an entire amount of actinides has a significant advantage from these development targets. In the present paper, we will discuss about our scenario of the homogeneous actinide recycling in the FR cycle system, based on our recent studies in the FaCT Project. The studies on the scenario of nuclear energy policy, the management and development of minor actinide (MA)-bearing fuel, reactor physics related to MA-loaded FR cores, and typical nuclear design of MA-loaded FR cores have shown the feasibility to recycle all MA in the future FR-equilibrium society. Also presented are the R&D programs to demonstrate the homogeneous actinide recycling, which are extensively conducted as one of the key national projects in Japan, as well as utilizing international cooperation.

Journal Articles

Structure of Au(111) and Au(100) single-crystal electrode surfaces at various potentials in sulfuric acid solution determined by in situ surface X-ray scattering

Kondo, Toshihiro*; Morita, Jun*; Hanaoka, Kazuya*; Takakusagi, Satoru*; Tamura, Kazuhisa; Takahashi, Masamitsu; Mizuki, Junichiro; Uosaki, Kohei*

Journal of Physical Chemistry C, 111(35), p.13197 - 13204, 2007/09

 Times Cited Count:78 Percentile:89.1(Chemistry, Physical)

Potential-dependent surface structures of Au(111) and Au(100) single-crystal electrodes in a 50 mM H$$_{2}$$SO$$_{4}$$ solution were investigated at an atomic level using in situ surface X-ray scattering (SXS) techniques. It was confirmed that both the Au(111) and Au(100) surfaces were reconstructed with an attached submonolayer of an oxygen species, most probably water, at 0 V (vs Ag/AgCl). Results at +0.95 V supported a previously suggested model for both the Au(111) and the Au(100) electrodes that, based on infrared and scanning tunneling microscopy measurements, the surfaces were a (1$$times$$1) structure with the coadsorbed sulfate anion and hydronium cation (H$$_{3}$$O$$^{+}$$). At +1.05 V, where a small amount of an anodic current flowed, adsorption of a monolayer of oxygen species was observed on both surfaces.

Journal Articles

Outline of fast reactor cycle technology development; Launch of FaCT project

Mukai, Kazuo; Sagayama, Yutaka; Kondo, Satoru; Iwamura, Takamichi; Sugiyama, Toshihide

Genshiryoku eye, 53(3), p.24 - 33, 2007/03

no abstracts in English

Journal Articles

Establishment of freezing model for reactor safety analysis

Kamiyama, Kenji; Brear, D. J.*; Tobita, Yoshiharu; Kondo, Satoru

Journal of Nuclear Science and Technology, 43(10), p.1206 - 1217, 2006/10

 Times Cited Count:22 Percentile:82.63(Nuclear Science & Technology)

A mechanistic simulation of molten core-material relocation is required to reasonably assess consequences of postulated core disruptive accidents (CDAs) in fast reactors (FRs). The dynamics of molten core-material freezing when it is driven into the channels surrounding the core region plays an important role since this affects fuel removal from the core region. Therefore, a mechanistic model for freezing behavior was developed and introduced into the FR safety analysis code, SIMMER-III, in this study. Based on the micro-physics of crystallization, two key assumptions, supercooling of melt in the vicinity of the wall and melt-wall contact resistance due to imperfect contact, were introduced. As a result, encouraging agreement both with measured melt-penetration lengths and freezing modes of UO$$_{2}$$ and metals was obtained. Furthermore, in order to reinforce the developed model, a semi-empirical correlation to predict the supercooling temperature was found. The developed model with the new correlation reproduced both stainless steel freezing and alumina freezing.

JAEA Reports

Leakage rate test for reactor containment vessel of HTTR

Kondo, Masaaki; Sekita, Kenji; Emori, Koichi; Sakaba, Nariaki; Kimishima, Satoru; Kuroha, Misao; Noji, Kiyoshi; Aono, Tetsuya; Hayakawa, Masato

JAEA-Testing 2006-002, 55 Pages, 2006/07


The leakage rate test for the reactor containment vessel of HTTR is conducted in accordance with the absolute pressure method provided in Japan Electric Association Code(JEAC4203). Although leakage test of a reactor containment vessel is, in general, performed in condition of reactor coolant pressure boundary to be opened in order to simulate an accident, the peculiar test method to HTTR which use the helium gas as reactor coolant has been established, in which the pressure boundary is closed to avoid the release of fission products into the environment of the reactor containment vessel. The system for measuring and calculating the data for evaluating the leakage rate for containment vessel of HTTR was developed followed by any modifications. Recently, the system has been improved for more accurate and reliable one with any useful functions including real time monitoring any conditions related to the test. In addition, the configuration of containment vessel boundary for the test and the calibration method for the detectors for measuring temperature in containment vessel have been modified by reflecting the revision of the Code mentioned above. This report describes the method, system configuration, and procedures for the leakage rate test for reactor containment vessel of HTTR.

JAEA Reports

Test results of HTTR control system

Motegi, Toshihiro; Iigaki, Kazuhiko; Saito, Kenji; Sawahata, Hiroaki; Hirato, Yoji; Kondo, Makoto; Shibutani, Hideki; Ogawa, Satoru; Shinozaki, Masayuki; Mizushima, Toshihiko; et al.

JAEA-Technology 2006-029, 67 Pages, 2006/06


The plant control performance of the IHX helium flow rate control system, the PPWC helium flow rate control system, the secondary helium flow rate control system, the inlet temperature control system, the reactor power control system and the outlet temperature control system of the HTTR are obtained through function tests and power-up tests. As the test results, the control systems show stable control response under transient condition. Both of inlet temperature control system and reactor power control system shows stable operation from 30% to 100%, respectively. This report describes the outline of control systems and test results.

JAEA Reports

Report of investigation on malfunction of reserved shutdown system in HTTR

Hamamoto, Shimpei; Iigaki, Kazuhiko; Shimizu, Atsushi; Sawahata, Hiroaki; Kondo, Makoto; Oyama, Sunao; Kawano, Shuichi; Kobayashi, Shoichi; Kawamoto, Taiki; Suzuki, Hisashi; et al.

JAEA-Technology 2006-030, 58 Pages, 2006/03


During normal operation of High Temperature engineering Test Reactor (HTTR) in Japan Atomic Energy Agency (JAEA), the reactivity is controlled by the Control Rods (CRs) system which consists of 32 CRs (16 pairs) and 16 Control Rod Drive Mechanisms (CRDMs). The CR system is located in stand-pipes accompanied by the Reserved Shutdown System (RSS). In the unlikely event that the CRs fail to be inserted, the RSS is provided to insert B$$_{4}$$C/C pellets into the core. The RSS shall be designed so that the reactor should be held subcriticality from any operation condition by dropping in the pellets. The RSS consists of B$$_{4}$$C/C pellets, hoppers which contain the pellets, electric plug, driving mechanisms, guide tubes and so on. In accidents when the CRs cannot be inserted, an electric plug is pulled out by a motor and the absorber pellets fall into the core by gravity. A trouble, malfunction of one RSS out of sixteen, occurred during a series of the pre-start up checks of HTTR on February 21, 2005. We investigated the cause of the RSS trouble and took countermeasures to prevent the issue. As the result of investigation, the cause of the trouble was attributed to the following reason: In the motor inside, The Oil of grease of the multiplying gear flowed down from a gap of the oil seal which has been deformed and was mixed with abrasion powder of brake disk. Therefore the adhesive mixture prevented a motor from rotating.

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