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

https://doi.org/10.1016/C2018-0-05383-9

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 950C, 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.

Development of new corrosion test equipment simulating sulfuric acid decomposition gas environment in a thermochemical hydrogen production process

Hirota, Noriaki; Kasahara, Seiji; Iwatsuki, Jin; Imai, Yoshiyuki; Ohashi, Hirofumi; Yan, X.; Tachibana, Yukio

Zairyo To Kankyo, 68(6), p.137 - 142, 2019/06

https://doi.org/10.3323/jcorr.68.137

New corrosion test equipment for high temperature gas of decomposed sulfuric acid was manufactured in order to ascertain flow rate of sulfuric acid in the piping, occurrence of sulfuric acid decomposition reaction in the equipment, and temperature distribution inside the furnace tube. The flow rate of the sulfuric acid solution was constantly measured using an ultrasonic flowmeter. The SO concentration at the inlet of the test equipment was almost the same as that at the inlet of the sulfuric acid decomposer in the hydrogen production plant assuming a high-temperature gas cooled reactor hydrogen-power cogeneration system (GTHTR300C). On the other hand, during a test, leakage of sulfuric acid occurred from the fitting part at the outlet side. Hence the temperature distribution of the fitting part at the outlet side was investigated using fluid analysis. As a result, it was found that the temperature at the fitting was low enough to use fluorine joint grease when the distance was 0.05 m or more away from the outlet side pipe. An improved furnace tube was manufactured and the temperature was measured again at fitting part of the outlet side. The temperature was lower that the temperature limit of the joint grease and almost the same as the temperature distribution in the fluid analysis, and leakage of sulfuric acid has not occurred to date.

Conceptual design of the iodine-sulfur process flowsheet with more than 50% thermal efficiency for hydrogen production

Kasahara, Seiji; Imai, Yoshiyuki; Suzuki, Koichi*; Iwatsuki, Jin; Terada, Atsuhiko; Yan, X.

Nuclear Engineering and Design, 329, p.213 - 222, 2018/04

https://doi.org/10.1016/j.nucengdes.2017.11.046

A conceptual design of a practical large scale plant of the thermochemical water splitting iodine-sulfur (IS) process flowsheet was carried out as a heat application of JAEA's commercial high temperature gas cooled reactor GTHTR300C plant design. Innovative techniques proposed by JAEA were applied for improvement of hydrogen production thermal efficiency; depressurized flash concentration HSO using waste heat from Bunsen reaction, prevention of HSO vaporization from a distillation column by introduction of HSO solution from a flash bottom, and I condensation heat recovery in an HI distillation column. Hydrogen of about 31,900 Nm/h would be produced by 170 MW heat from the GTHTR300C. A thermal efficiency of 50.2% would be achievable with incorporation of the innovative techniques and high performance HI concentration and decomposition components and heat exchangers expected in future R&D.

Conceptual design of iodine-sulfur process flowsheet with more than 50% thermal efficiency for hydrogen production

Kasahara, Seiji; Imai, Yoshiyuki; Suzuki, Koichi*; Iwatsuki, Jin; Terada, Atsuhiko; Yan, X.

Proceedings of 8th International Topical Meeting on High Temperature Reactor Technology (HTR 2016) (CD-ROM), p.491 - 500, 2016/11

A conceptual design of a practical large scale plant of the thermochemical water splitting iodine-sulfur (IS) process flowsheet was carried out as a heat application of Japan Atomic Energy Agency's commercial Gas Turbine High Temperature Reactor Cogeneration (GTHTR300C) plant design. Innovative techniques proposed by JAEA were applied for improvement of hydrogen production thermal efficiency; flash concentration of HSO using waste heat from Bunsen reaction, prevention of HSO vaporization from a distillation column by introduction of HSO solution, and I condensation heat recovery by direct contact heat exchange in the HI distillation column. A simulation of material and heat balance showed hydrogen of about 31,900 Nm/h was produced by 170 MW heat from the GTHTR300C. A process thermal efficiency of 50.2% was achievable with incorporation of the innovative techniques and several high performance components expected in future R&D.

Heat transport analysis in a district heating system applying waste heat from GTHTR300, a commercial design of high-temperature gas-cooled reactor

Kasahara, Seiji; Murata, Tetsuya*; Kamiji, Yu; Terada, Atsuhiko; Yan, X.; Inagaki, Yoshiyuki; Mori, Michitsugu*

Mechanical Engineering Journal (Internet), 3(3), p.15-00616_1 - 15-00616_16, 2016/06

http://doi.org/10.1299/mej.15-00616

A district heating system for household heating and road snow melting utilizing waste heat from GTHTR300, a heat-electricity cogeneration design of high temperature gas-cooled reactor, was analyzed. The application area was Sapporo and Ishikari, cities with heavy snowfall in northern Japan. The heat transport analyses were performed by modeling components to estimate heat supply profile; the secondary loops between the GTHTR300s and the heat-application area; heat exchangers connecting the secondary loops to the tertiary loops of the district-heating pipes; and the tertiary loops between the heat exchangers and houses and roads. Though double pipes for the secondary loops were advantageous for having less heat loss and a smaller excavation area, these advantages did not compensate for the higher construct cost of the pipes. To satisfy heat demand in the month of maximum requirement, 520-529 MW of heat were supplied by 3 GTHTR300s and delivered by 6 secondary loops, 3,450 heat exchangers about 90 m long, and 3,450 tertiary loops. Heat loss to the ground from the tertiary loops comprised 80%-90% of the heat loss. More than 90% of the construction cost went into thermal insulators. The thickness and properties of the thermal insulator must be reevaluated for economical heat delivery.

Process evaluation of use of High Temperature Gas-cooled Reactors to an ironmaking system based on Active Carbon Recycling Energy System

Hayashi, Kentaro*; Kasahara, Seiji; Kurihara, Kohei*; Nakagaki, Takao*; Yan, X.; Inagaki, Yoshiyuki; Ogawa, Masuro

ISIJ International, 55(2), p.348 - 358, 2015/02

https://doi.org/10.2355/isijinternational.55.348

Reducing coking coal consumption and CO emissions by application of iACRES (ironmaking system based on active carbon recycling energy system) was investigated using process flow modeling to show effectiveness of HTGRs (high temperature gas-cooled reactors) adoption to iACRES. Two systems were evaluated: a SOEC (solid oxide electrolysis cell) system using CO electrolysis and a RWGS (reverse water-gas shift reaction) system using RWGS reaction with H produced by IS (iodine-sulfur) process. Both the effects on saving of the coking coal and reduction of CO emissions were greater in the RWGS system. It was the reason of the result that excess H which was not consumed in the RWGS reaction was used as reducing agent in the BF as well as CO. Heat balance in the HTGR, SOEC and RWGS modules were evaluated to clarify process components to be improved. Optimization of the SOEC temperature was desired to reduce Joule heat input for high efficiency operation of the SOEC system. Higher H production thermal efficiency in the IS process for the RWGS system is effective for more efficient HTGR heat utilization. The SOEC system was able to utilize HTGR heat to reduce CO emissions more efficiently by comparing CO emissions reduction per unit heat of HTGR.

Economic evaluation of HTGR IS process hydrogen production system

Iwatsuki, Jin; Kasahara, Seiji; Kubo, Shinji; Inagaki, Yoshiyuki; Kunitomi, Kazuhiko; Ogawa, Masuro

JAEA-Review 2014-037, 14 Pages, 2014/09

JAEA-Review-2014-037.pdf:8.84MB

Thermochemical iodine-sulfur (IS) process is one of the promising technologies, which harnesses heat energy of high temperature gas-cooled reactors (HTGRs). An economic estimation of hydrogen production by a future commercial HTGR-IS process hydrogen production system was performed on the basis of economic evaluation data of an existing commercial hydrogen production plant using fossil fuel as a raw material. Hydrogen production cost was estimated at 25.4 JPY/Nm under this estimation conditions. Capital cost and energy cost account for 13% and 78% of the total hydrogen production cost, respectively. To decrease HTGR construction cost, to increase HTGR availability, to improve hydrogen production thermal efficiency are important for cost reduction of hydrogen. The cost will be competitive with estimated costs by fossil fuel hydrogen production methods. It is appropriate that the hydrogen production cost is set for a goal of present R&Ds.

Process flow sheet evaluation of a nuclear hydrogen steelmaking plant applying very high temperature reactors for efficient steel production with less CO emissions

Kasahara, Seiji; Inagaki, Yoshiyuki; Ogawa, Masuro

Nuclear Engineering and Design, 271, p.11 - 19, 2014/05

https://doi.org/10.1016/j.nucengdes.2013.11.002

Nuclear hydrogen steelmaking (NHS) system was evaluated by flow sheet analysis using very high temperature reactors (VHTRs) and thermochemical hydrogen production IS process. Heat input and CO emissions including material production, material transportation, and power generation were evaluation criteria. Though total heat input to the NHS system was 130-142% of a conventional blast furnace steelmaking system, CO emissions were 13-21%. Pre-heating of hydrogen by coal combustion before blowing to a shaft furnace was effective to decrease heat input although CO emissions increased. Direct nuclear pre-heating was also effective without increase of CO emissions if close location of the nuclear reactor to the steelmaking plant was publicly accepted. Hydrogen production thermal efficiency had a significant influence on the heat input. Conceptual design of a plant unit of the NHS system producing steel of 1.47 10 t/y with 2 VHTRs of 600MW heat and one shaft furnace and electric arc furnace was proposed. This article is revised from a proceeding presented in HTR2012.

Density of Bunsen reaction solution and viscosity of poly-hydriodic acid

Kubo, Shinji; Yoshino, Koji*; Takemoto, Jumpei*; Kasahara, Seiji; Imai, Yoshiyuki; Onuki, Kaoru

JAEA-Technology 2012-037, 20 Pages, 2013/01

JAEA-Technology-2012-037.pdf:17.29MB

Densities of Bunsen reaction solutions in the iodine-sulfur process were measured with an oscillating U-tube density meter. Two types of the solutions were prepared to simulate sulfuric acid solutions and hydriodic acid solutions of the Bunsen reaction step. The former solution ranged in concentration from 0 to 45 wt% of sulfuric acid containing HI and I of 0-2 mole%; the latter solution contained 0-17 mole% I, 1-15 mole% HI and 0-2 mole% HSO. The temperature of the measured solution were 10-60 C. It was found that, in both solutions, the effect of HI and I concentration on the density could well be represented by using a kind of mole fraction of iodine atom. Based on the finding, a set of correlation equations between the densities and the compositions were derived. Additionally, viscosities of ploy-hydriodic acid were measured using an oscillating viscosity meter in temperature range of 5-40 C, and in the composition range of 0-17 mole% I and 1-15 mole% HI; a empirical equation to calculate viscosity from the composition and the temperature are obtained.

Components for sulfuric acid processing in the IS process

Noguchi, Hiroki; Kubo, Shinji; Iwatsuki, Jin; Kasahara, Seiji; Tanaka, Nobuyuki; Imai, Yoshiyuki; Terada, Atsuhiko; Takegami, Hiroaki; Kamiji, Yu; Onuki, Kaoru; et al.

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

The Japan Atomic Energy Agency (JAEA) has been conducting research and development on a thermochemical iodine-sulfur (IS) process. An examination is planned to verify the integrity of the components in the sulfuric acid decomposition section. A bayonet-type sulfuric acid decomposer made of SiC ceramics, a key component in the section, was test-fabricated. In parallel, a direct-contact heat exchanger (DCHX) is contemplated for use in the sulfuric acid decomposition section to simplify the process. Although the concept is very attractive, little is known about the heat and mass transfer behavior in the DCHX. Therefore, a test apparatus was constructed to measure the gas-phase mass transfer coefficients required for the optimal design of the DCHX. These coefficients of water were acquired and compared with an empirical correlation. The experimental data were in good agreement with those obtained from empirical correlation, and thus, the apparatus was confirmed to be reasonable.