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JAEA Reports

Technology information on High Temperature Gas-cooled Reactor (HTGR)

HTGR Design Group, HTGR Project Management Office

JAEA-Technology 2023-019, 39 Pages, 2024/01

JAEA-Technology-2023-019.pdf:1.34MB

In order to realize the development of the demonstration reactor of High Temperature Gas-cooled Reactor (HTGR) with a target of starting operation in the 2030s, as indicated in the "Basic Policy for GX Realization" (Cabinet Decision on February 10, 2023) and the Working Group on Innovative Reactors of METI, Japan Atomic Energy Agency (JAEA) has been working on the development of a standard for the development of a HTGR under the Atomic Energy Society of Japan and the Japan Society of Mechanical Engineers. In addition, JAEA has been commissioned by the Agency for Natural Resources and Energy of the Ministry of Economy, Trade and Industry (METI) to conduct the "Demonstration Project for Mass Hydrogen Production Technology Using Ultra-High Temperatures" and has been promoting a hydrogen production project using the HTTR (High Temperature Engineering Test Reactor). Furthermore, in collaboration with the National Nuclear Laboratory (NNL) of the United Kingdom and the National Centre for Nuclear Research (NCBJ) of Poland, JAEA are aiming to strengthen the international competitiveness of HTGR technology by further upgrading the HTGR technology developed in Japan through the construction and operation of the HTTR. In response to the growing interest in HTGR development in Japan and abroad, we have developed FAQs on HTGR related technologies in order to provide accurate technical information on HTGRs.

Journal Articles

Development of an RPV cooling system for HTGRs

Takamatsu, Kuniyoshi

Kakushinteki Reikyaku Gijutsu; Mekanizumu Kara Soshi, Shisutemu Kaihatsu Made, p.179 - 183, 2024/01

The HTGR has excellent safety, and even in the event of an accident where the reactor coolant is lost, the decay heat and residual heat in the core can be dissipated from the outer surface of the RPV, so the fuel temperature never exceeds the limit value, and the core stabilizes. On the other hand, regarding the cooling system that transports the heat emitted from the RPV to the final heat sink, an active cooling system using forced circulation of water by a pump, etc., and a passive cooling system using natural circulation of the atmosphere have been proposed. However, there is a problem that the cooling performance is affected by the operation of dynamic equipment and weather conditions. This paper presents an overview of a new cooling system concept using radiative cooling, which has been proposed to solve the above problem, and introduces the results of analysis and experiments aimed at confirming the feasibility of this concept.

Journal Articles

Fuel cycle scenarios and back-end technologies of HTGR in Japan

Fukaya, Yuji; Goto, Minoru; Shibata, Taiju

IAEA-TECDOC-2040, p.133 - 136, 2023/12

Japan has developed back-end technologies to establish a multi-recycling fuel cycle with fast breeder reactors (FBRs) to ensure energy resources. Even though the development of FBR has been retreated to one of fundamental research, the reprocessing technologies for uranium fuel and disposal technologies had been completed for Light Water Reactor (LWR) fuel cycle on the process. These technologies were inherited to utilities and are about to be practical. Now, Japan had been completed High Temperature Engineering Test Reactor (HTTR) a prototype and research reactor, a commercial High Temperature Gas-cooled Reactor (HTGR) design Gas Turbine High Temperature Reactor 300 (GTHTR300) with related reprocessing technologies, and is planning domestic demonstration reactor project. In this context, a representative fuel cycle policy is reprocessing in Japan. However, Japan has investigated various fuel cycle scenarios to expand the usage of the commercial HTGR. Then, we would like to introduce the scenarios and development status of related technologies in the present study.

Journal Articles

New market opened up by advanced nuclear reactors (Chapter 3, 4, 5, 7)

Kamide, Hideki; Kawasaki, Nobuchika; Hayafune, Hiroki; Kubo, Shigenobu; Chikazawa, Yoshitaka; Maeda, Seiichiro; Sagayama, Yutaka; Nishihara, Tetsuo; Sumita, Junya; Shibata, Taiju; et al.

Jisedai Genshiro Ga Hiraku Atarashii Shijo; NSA/Commentaries, No.28, p.14 - 36, 2023/10

Developments of next generation nuclear reactors, e.g., Fast Reactor, and High Temperature Gas cooled Reactor, are in progress. They can contribute to markets of electricity and industrial heat utilization in the world including Japan. Here, current status of reactor developments in Japan and also situation in the world are summarized, especially for activities of Generation IV International Forum (GIF), developments of Fast Reactor and High Temperature Gas cooled Reactor in Japan, and SMR movements in the world.

Journal Articles

Molecular dynamics analysis of reactor graphite for preparing thermal neutron scattering law

Okita, Shoichiro; Goto, Minoru

Proceedings of 12th International Conference on Nuclear Criticality Safety (ICNC2023) (Internet), 10 Pages, 2023/10

JAEA Reports

Operation, test, research and development of the High Temperature Engineering Test Reactor (HTTR) (FY2021)

Department of HTTR

JAEA-Review 2023-016, 82 Pages, 2023/09

JAEA-Review-2023-016.pdf:2.31MB

The High Temperature Engineering Test Reactor (HTTR) is the first Japanese High Temperature Gas-cooled Reactor (HTGR) with 30MW in thermal power and 950$$^{circ}$$C of maximum outlet coolant temperature that is constructed by the Japan Atomic Energy Agency located at Oarai-machi, Higashiibaraki-gun, Ibaraki-ken, Japan. The purpose of the HTTR is establishment of basic HTGR technologies, demonstration of HTGR safety characteristics and so on. The HTTR has had a lot of experience of HTGRs' operation and maintenance throughout rated power operations, safety demonstration tests, long-term high temperature operations and demonstration tests relevant to HTGRs' R&Ds. In the fiscal year 2021, as the HTTR completed activities to conform to the New Regulatory Requirements of Nuclear Regulation Authority, The HTTR restarted since the 2011 off the Pacific coast of Tohoku Earthquake and carried out the Loss-of-forced cooling test without Vessel Cooling System (VCS) operational at 9MW (Three gas circulators trip and VCS is stopped.) as the safety demonstration test. This report summarizes the activities carried out in the fiscal year 2021, which were the situation of the New Regulatory Requirements screening of the HTTR, the operation and maintenance of the HTTR, R&Ds relevant to commercial-scale HTGRs, the international cooperation on HTGRs and so on.

JAEA Reports

Study of fabrication of SiC-matrixed fuel compact for HTGR

Kawano, Takahiro*; Mizuta, Naoki; Ueta, Shohei; Tachibana, Yukio; Yoshida, Katsumi*

JAEA-Technology 2023-014, 37 Pages, 2023/08

JAEA-Technology-2023-014.pdf:2.35MB

Fuel compact for High Temperature Gas-cooled Reactor (HTGR) is fabricated by calcinating a matrix consisting of graphite and binder with the coated fuel particle. The SiC-matrixed fuel compact uses a new matrix made of silicon carbide (SiC) replacing the conventional graphite. Applying the SiC-matrixed fuel compact for HTGRs is expected to improve their performance such as power densities. In this study, the sintering conditions for applying SiC as the matrix of fuel compacts for HTGR are selected, and the density and thermal conductivity of the prototype SiC are measured.

Journal Articles

Reactor physics experiment on a graphite-moderated core to construct integral experiment database for HTGR

Okita, Shoichiro; Fukaya, Yuji; Sakon, Atsushi*; Sano, Tadafumi*; Takahashi, Yoshiyuki*; Unesaki, Hironobu*

Nuclear Science and Engineering, 197(8), p.2251 - 2257, 2023/08

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

Journal Articles

Investigation of potential of vacuum-free femtosecond laser sintering for direct printing using silicon carbide nanoparticles without inorganic binder

Kawabori, Tatsuru*; Watanabe, Masashi; Imai, Yoshiyuki; Ueta, Shohei; Yan, X.; Mizoshiri, Mizue*

Applied Physics A, 129(7), p.498_1 - 498_9, 2023/07

 Times Cited Count:0 Percentile:0(Materials Science, Multidisciplinary)

We investigated a potential of femtosecond laser sintering of silicon carbide (SiC) using the nanoparticles in air. A SiC nanoparticle ink including polyvinylpyrrolidone and ethylene glycol exhibited intense absorption by SiC nanoparticles at the wavelength of 780 nm. The whole of the sintered film patterns from the surface to the bottom underwent significant oxidation at a scanning speed of 1 mm/s, suggesting that the excessive energy irradiation generated silicon oxides. In contrast, the patterns fabricated by laser scanning at a raster pitch of 30 $$mu$$m at which a sintered area was observed at a scanning speed of 5 mm/s, exhibited no significant difference in oxidation of the raw SiC nanoparticles except for the surfaces from 1.72 $$mu$$m. These results indicate that the irradiation of femtosecond laser pulses generated the sintered SiC patterns without additional atmospheric oxidation of the raw materials because of its low heat accumulation. In additions, the dispersant of polyvinylpyrrolidone and ethylene glycol did not affect the sintering by an X-ray photoelectron spectroscopy. This vacuum-free direct printing technique has the potential for additive manufacturing.

Journal Articles

R&D progress of thermochemical hydrogen production iodine-sulfur process in JAEA

Kubo, Shinji

Nihon Enerugi Gakkai Kikan-Shi Enerumikusu, 102(4), p.428 - 438, 2023/07

no abstracts in English

JAEA Reports

Report of summer holiday practical training on 2022

Ishitsuka, Etsuo; Ho, H. Q.; Kitagawa, Kanta*; Fukuda, Takahito*; Ito, Ryo*; Nemoto, Masaya*; Kusunoki, Hayato*; Nomura, Takuro*; Nagase, Sota*; Hashimoto, Haruki*; et al.

JAEA-Technology 2023-013, 19 Pages, 2023/06

JAEA-Technology-2023-013.pdf:1.75MB

Eight people from five universities participated in the 2022 summer holiday practical training with the theme of "Technical development on HTTR". The participants practiced the feasibility study for nuclear battery, the burn-up analysis of HTTR core, the feasibility study for $$^{252}$$Cf production, the analysis of behavior on loss of forced cooling test, and the thermal-hydraulic analysis near reactor pressure vessel. In the questionnaire after this training, there were impressions such as that it was useful as a work experience, that some students found it useful for their own research, and that discussion with other university students was a good experience. These impressions suggest that this training was generally evaluated as good.

JAEA Reports

Development of wide range monitor for HTTR; Improvement for heat resistance performance against heat cycle

Kozawa, Takayuki; Suganuma, Takuro; Homma, Fumitaka; Higashimura, Keisuke*; Ukai, Takayuki*; Saito, Kenji

JAEA-Technology 2023-007, 24 Pages, 2023/06

JAEA-Technology-2023-007.pdf:2.24MB

To improve the reliability of the HTTR wide range monitor in a high-temperature environment, structural changes of the wide range monitor were investigated. It was clear that the structure for directly joins of the MI cable core wire and metal tube instead of the joins with lead wire is the most reliable method with shortest way. From a result of the thermal cycle tests and high temperature endurance tests for a mock-up connecting this connection parts, it was clear that the soundness of the connection part was maintained under the usage conditions of the HTTR.

JAEA Reports

Study on disposal of waste from reprocessing for commercial HTGR spent fuel

Fukaya, Yuji; Maruyama, Takahiro; Goto, Minoru; Ohashi, Hirofumi; Higuchi, Hideaki

JAEA-Research 2023-002, 19 Pages, 2023/06

JAEA-Research-2023-002.pdf:1.48MB

A study on disposal of waste derived from commercial High Temperature Gas-cooled Reactor ("HTGR") has been performed. Because of significant difference between the reprocessing of Light Water Reactor ("LWR") and that of HTGR due to difference in structures of the fuel, adoptability of the laws relating to reprocessing waste disposal, which is enacted for LWR, to HTGR waste should be confirmed. Then, we compared the technologies and waste of reprocessing and evaluated radioactivity concentration in graphite waste by activation and contamination based on whole core burn-up calculation. As a result, it was found that SiC residue waste should be disposed of into a geological repository as 2nd class designated radioactive waste in the Designated Radioactive Waste Final Disposal Act (Act No.117 of 2000), by way of amendment of the applicable order, same as hull and end-piece of LWR, and graphite waste should be shallowly disposed of than geological disposal as 2nd class waste for pit disposal in the Act on the Regulation of Nuclear Source Material, Nuclear Fuel Material and Reactors (Act No.166 of 1957) same as a channel box of LWR.

Journal Articles

Current status and prospects of technology development for hydrogen production using high temperature gas-cooled reactor

Kubo, Shinji

Suiso Enerugi Shisutemu, 48(2), p.126 - 132, 2023/06

no abstracts in English

JAEA Reports

Differential pressure rise event for filters of HTTR primary helium gas circulators, 1; Investigation of differential pressure rise event

Nemoto, Takahiro; Arakawa, Ryoki; Kawakami, Satoru; Nagasumi, Satoru; Yokoyama, Keisuke; Watanabe, Masashi; Onishi, Takashi; Kawamoto, Taiki; Furusawa, Takayuki; Inoi, Hiroyuki; et al.

JAEA-Technology 2023-005, 33 Pages, 2023/05

JAEA-Technology-2023-005.pdf:5.25MB

During shut down of the HTTR (High Temperature engineering Test Reactor) RS-14 cycle, an increasing trend of filter differential pressure for the helium gas circulator was observed. In order to investigate this phenomenon, the blower of the primary helium purification system was disassembled and inspected. As a result, it is clear that the silicon oil mist entered into the primary coolant due to the deterioration of the charcoal filter performance. The replacement and further investigation of the filter are planning to prevent the reoccurrence of the same phenomenon in the future.

Journal Articles

Research on improvement of HTGR core power-density, 4; Feasibility study for a reactor core

Okita, Shoichiro; Mizuta, Naoki; Takamatsu, Kuniyoshi; Goto, Minoru; Yoshida, Katsumi*; Nishimura, Yosuke*; Okamoto, Koji*

Proceedings of 30th International Conference on Nuclear Engineering (ICONE30) (Internet), 10 Pages, 2023/05

Journal Articles

Validation of evaluation model for analysis of steam reformer in HTGR hydrogen production plant

Ishii, Katsunori; Aoki, Takeshi; Isaka, Kazuyoshi; Noguchi, Hiroki; Shimizu, Atsushi; Sato, Hiroyuki

Proceedings of 30th International Conference on Nuclear Engineering (ICONE30) (Internet), 9 Pages, 2023/05

Journal Articles

Development of safety design philosophy of HTTR-Heat Application Test Facility

Aoki, Takeshi; Shimizu, Atsushi; Noguchi, Hiroki; Kurahayashi, Kaoru; Yasuda, Takanori; Nomoto, Yasunobu; Iigaki, Kazuhiko; Sato, Hiroyuki; Sakaba, Nariaki

Proceedings of 30th International Conference on Nuclear Engineering (ICONE30) (Internet), 9 Pages, 2023/05

The safety design philosophy is developed for the HTTR (High Temperature Engineering Test Reactor) heat application test facility connecting high temperature gas-cooled reactor (HTGR) and the hydrogen production plant. The philosophy was proposed to apply proven conventional chemical plant standards to the hydrogen production facility for ensuring public safety against anticipated disasters caused by high pressure and combustible gases. The present study also proposed the safety design philosophy to meet specific safety requirements identified to the nuclear facilities with coupling to the hydrogen production facility such as measures to ensure a capability of normal operation of the nuclear facility against a fire and/or explosion of leaked combustible material, and fluctuation of amount of heat removal occurred in the hydrogen production plant. The safety design philosophy will be utilized to establish its basic and detailed designs of the HTTR-heat application test facility.

Journal Articles

Development plan for coupling technology between high temperature gas-cooled reactor HTTR and hydrogen production facility, 1; Overview of the HTTR heat application test plan to establish high safety coupling technology

Nomoto, Yasunobu; Mizuta, Naoki; Morita, Keisuke; Aoki, Takeshi; Okita, Shoichiro; Ishii, Katsunori; Kurahayashi, Kaoru; Yasuda, Takanori; Tanaka, Masato; Isaka, Kazuyoshi; et al.

Proceedings of 30th International Conference on Nuclear Engineering (ICONE30) (Internet), 7 Pages, 2023/05

Journal Articles

Improvement of cooling performance of reactor pressure vessel using passive cooling

Banno, Masaki*; Funatani, Shumpei*; Takamatsu, Kuniyoshi

Proceedings of 30th International Conference on Nuclear Engineering (ICONE30) (Internet), 7 Pages, 2023/05

A fundamental study on the safety of a passive cooling system for the RPV with radiative cooling is conducted. The object of this study is to demonstrate that passive RPV cooling system with radiative cooling is extremely safe and reliable even in the event of natural disasters. Therefore, an experimental apparatus, which is about 1/20 scale of the actual cooling system, was fabricated with several stainless steel containers. The surface of the heating element in the experimental apparatus simulates the surface of the RPV, and the heating element generates natural convection and radiation. A comparison of the Grashof number between the actual cooling system and the experimental apparatus confirmed that both were turbulent, and the experimental results as a scale model are valuable. Moreover, the experimental results confirmed that the heat generated from the surface of the RPV during the rated operation can be removed.

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