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Aihara, Jun; Kuroda, Masatoshi*; Tachibana, Yukio
Mechanical Engineering Journal (Internet), 9(4), p.21-00424_1 - 21-00424_13, 2022/08
It is important to improve oxidation resistance of fuel for huge oxygen ingress into core to improve safety of high temperature gas-cooled reactors (HTGRs), because almost volume of cores of HTGRs consist of graphite. In this study, simulated oxidation resistant fuel elements, of which matrix is mixture of SiC and graphite, has been fabricated by hot press method. In order to maintain structural integrity of fuel element under accident conditions, high-strength fuel elements should be developed. In order to identify optimal hot press conditions for preparing high-strength fuel elements, effect of hot press conditions on mechanical strength properties of fuel elements should be evaluated quantitatively. In the present study, response surface model, which represents relationship between hot press conditions and mechanical strength properties, has been constructed by introducing statistical design of experiments (DOE) approaches, and optimal hot press conditions were estimated by model.
Aihara, Jun; Kuroda, Masatoshi*; Tachibana, Yukio
Proceedings of 28th International Conference on Nuclear Engineering (ICONE 28) (Internet), 9 Pages, 2021/08
To maintain the structural integrity of fuel elements for a high-temperature gas-cooled reactor (HTGR) under disaster conditions, strong and oxidation-resistant fuel elements should be further developed. The HTGR fuel elements employ a hot-pressed silicon carbide (SiC)/carbon (C) mixed matrix to improve the oxidative resistance. Hot-press conditions such as pressure, temperature, and duration would be one of the factors that affect the strength of the HTGR fuel elements. To identify the optimal hot-press conditions for preparing the high-strength fuel elements, modelling their effects on the mechanical-strength properties of the HTGR fuel elements should be evaluated quantitatively. In this study, the response surface model, which represents the relationship between the hot-press conditions and the mechanical-strength properties, has been constructed by introducing statistical design-of-experiment approaches.
Goto, Minoru; Inaba, Yoshitomo; Aihara, Jun; Ueta, Shohei; Tachibana, Yukio
no journal, ,
JAEA has performed the research and development of the SiC matrix fuel, which is an oxidation resistant fuel against an air ingress accident, to establish the fundamental technologies. In this study, a nuclear thermal design was performed for the HTGR with the SiC matrix fuel.
Aihara, Jun; Ueta, Shohei; Honda, Masaki*; Ogawa, Hiroaki; Shibata, Taiju; Mizuta, Naoki; Inaba, Yoshitomo; Tachibana, Yukio
no journal, ,
Development of fabrication technology of fuel element of high temperature gas-cooled reactor with SiC/C mixed matrix was carried out to modify oxidation resistance. Dummy fuel elements with matrix, which Si/C ratio (about 0.551) was three times as large as those fabricated in precursor research, were fabricated. No Si peak was detected in XRD of matrix.
Kuroda, Masatoshi*; Tojo, Takuya*; Yamamoto, Takenori*; Aihara, Jun; Tachibana, Yukio
no journal, ,
High temperature gas-cooled reactor (HTGR) is a fourth generation nuclear reactor with inherent safety. In recent years, fuel elements with oxidation resistance has been developed for use in HTGR. In order to maintain the structural integrity of the oxidation resistant fuel element under accident conditions, a technique to fabricate a high-strength fuel should be required. In the present study, hot pressing conditions have been considered as the parameters which affect the strength of the oxidation resistant fuel compact, and a model has been created to predict the strength of the fuel compact from the hot pressing conditions by applying statistical approaches. The hot pressing conditions which can fabricate the high-strength oxidation resistant fuel element were also predicted by the model.
Tojo, Takuya*; Yamamoto, Takenori*; Kuroda, Masatoshi*; Aihara, Jun; Tachibana, Yukio
no journal, ,
Fuel compact of high-temperature gas-cooled reactor (HTGR) with inherent safety employs fuel component which was molded from graphite. Development of oxidation-resistant fuel component has been advancing at present, which is fuel component having oxidation resistance formed by SiC. In this study, mechanical properties were obtained on oxidation-resistant fuel components prepared under various molding parameters. Young's modulus was measured by ultrasonic pulse velocity test, and compressive strength was measured by compression test. High correlation was not observed between Young's modulus and hot pressing conditions of temperature and time. There was no correlation between compressive strength and hot pressing time in range of hot pressing temperature of 1573-1873 K and time of 40-120 min, but high negative correlation was observed within range of hot pressing temperatures. Therefore, it was predicted that compressive strength was increased by decreasing hot pressing temperature.
Tachibana, Yukio; Ohira, Koichi*; Kuroda, Masatoshi*
no journal, ,
For the purpose of upgrading safety of High Temperature Gas-cooled Reactor (HTGR), research on advanced fuel element was conducted with cooperation of Nuclear Fuel Industries and Kumamoto University. The advanced fuel element contains SiC as the matrix material and oxidation resistance is highly improved so that shape and integrity of the fuel element should be maintained even when large unexpected amount of air enters into the core in the air ingress (pipe rupture) accident which is a typical event for the HTGR. This presentation shows outlines of the contracted research from FY2014 to 2016.
Honda, Masaki*; Yasuda, Atsushi*; Ohira, Koichi*; Tachibana, Yukio
no journal, ,
For the purpose of upgrading safety of High Temperature Gas-cooled Reactor (HTGR), research on inspection technology for advanced fuel element was conducted with cooperation of JAEA from FY2014 to 2016. The advanced fuel element contains SiC as the matrix material and oxidation resistance is highly improved so that shape and integrity of the fuel element should be maintained even when large unexpected amount of air enters into the core in the air ingress (pipe rupture) accident which is a typical event for the HTGR. For the inspection technology, evaluation and inspection methods on homogeneity of SiC/C matrix and distribution of coated fuel particles as well as dissolution methods of coated fuel particles and SiC/C matrix for evaluation of failure fraction were developed and established.
