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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.
Sasaki, Koei; Miura, Shuichiro*; Fukumoto, Kenichi*; Goto, Minoru; Ohashi, Hirofumi
Proceedings of 28th International Conference on Nuclear Engineering (ICONE 28) (Internet), 6 Pages, 2021/08
Cs-Bi and Cs-Sb absorbed graphite samples (Cs-Bi/graphite and Cs-Sb/graphite) were synthesized and their high temperature chemical stabilities were tested up to 1500
C by TG and analyzed by TEM-EDS for the development of Cs trap material in high temperature gas-cooled reactor (HTGR) fuel particles. It was observed that Cs was stabilized by Sb but not by Bi in the specimens after the TG test. A rapid weight loss from 800 to 1000C may be caused by evaporation of Cs (boiling point: 671C) was seen in the TG result of both specimens. Precipitated Cs-Sb substance in the graphite matrix were not resolved even after the 1500C heating. The chemical composition of the Cs-Sb was specified as Cs
Sb. The experimental results suggest that Sb have potential to be a Cs getter material in graphite matrix. Long term heating test should be performed to confirm adaptability of Sb for Cs trap material in HTGR fuel particles.
Aihara, Jun; Ueta, Shohei; Honda, Masaki*; Mizuta, Naoki; Goto, Minoru; Tachibana, Yukio; Okamoto, Koji*
Journal of Nuclear Science and Technology, 58(1), p.107 - 116, 2021/01
Times Cited Count：0 Percentile：0.01(Nuclear Science & Technology)The concept of a Pu-burner high temperature gas-cooled reactor (HTGR) has been proposed for purpose of more safely reducing amount of recovered Pu. This concept employs coated fuel particles (CFPs) with ZrC coated PuO
-YSZ kernel and with tristructural (TRISO) coating for very high Pu burn-up and high nuclear proliferation resistance. In this report, we investigate the microstructure of the region that includes the surface of an as-fabricated CeO-YSZ kernel simulating PuO-YSZ kernel. We found both Zr-rich grains and Ce-rich grains to be densely distributed in that region including surface of CeO-YSZ kernel. On the other hand, it has been reported that there was a porous region near surface of the CeO-YSZ kernel of Batch I. This finding confirms that Ce-rich grains near surface of CeO-YSZ kernels coated with ZrC layers have been corroded during the deposition of the ZrC layer, whereas the Zr-rich grains were hardly affected.
Aihara, Jun; Yasuda, Atsushi*; Ueta, Shohei; Ogawa, Hiroaki; Honda, Masaki*; Ohira, Koichi*; Tachibana, Yukio
Nihon Genshiryoku Gakkai Wabun Rombunshi, 18(4), p.237 - 245, 2019/12
Development of fabrication and inspection technologies of oxidation resistant fuel element for improvement of safety of high temperature gas-cooled reactors (HTGRs) in severe oxidation accident was carried out. Simulated coated fuel particles (CFPs), alumina particles, were over-coated with mixed powder of Si, C and small amount of resin to form over-coated particles, and over-coated particles were molded and hot-pressed to sinter simulated oxidation resistant fuel elements with SiC/C mixed matrix. Simulated oxidation resistant fuel elements with matrix whose Si/C mole ratio is 1.00 were fabricated. Failure fraction of CFPs in fuel elements is one of very important inspection subjects of HTGR fuel. It is essential that CFPs are extracted from fuel elements without additional failure. Development of method for extraction of CFPs was carried out. Desolation of SiC by KOH method or pressurized acidolysis method should be applied to extraction of CFPs.
Aihara, Jun; Ueta, Shohei; Honda, Masaki*; Mizuta, Naoki; Goto, Minoru; Tachibana, Yukio; Okamoto, Koji*
Journal of Nuclear Materials, 522, p.32 - 40, 2019/08
Times Cited Count：3 Percentile：31.89(Materials Science, Multidisciplinary)In order to realize Pu-burner high temperature gas-cooled reactor (HTGR), coated fuel particles (CFPs) with PuO-yittria stabilized zirconia (YSZ) fuel kernel coated with ZrC is employed for high nuclear proliferation resistance and very high burn-up. Japan Atomic Energy Agency (JAEA) have carried out ZrC coatings of particles which simulated PuO-YSZ kernels (CeO-YSZ particles or commercially available YSZ particles). Ce was used as simulating element of Pu. In this manuscript, microstructures of ZrC coated CeO-YSZ or YSZ particles were reported.
Aihara, Jun; Honda, Masaki*; Ueta, Shohei; Ogawa, Hiroaki; Ohira, Koichi*; Tachibana, Yukio
Nihon Genshiryoku Gakkai Wabun Rombunshi, 18(1), p.29 - 36, 2019/03
Japan Atomic Energy Agency carried out development of fabrication technology of oxidation resistant fuel element for improvement of safety of high temperature gas-cooled reactors in serious oxidation accident, based on precursor research in former JAEA. Dummy coated fuel particles (alumina particles) were over-coated with mixed powder of Si, C and small amount of resin to form over-coated particles, and over-coated particles were molded and hot-pressed to sinter dummy oxidation resistant fuel elements with SiC/C mixed matrix. We fabricated dummy oxidation resistant fuel elements with matrix whose Si/C mole ratio (about 0.551) is three times as large as that in precursor research. Si peak was not detected by X-ray diffraction of matrix. Better oxidation resistant was confirmed with oxidation test in 20% O at 1673 K than that of ordinal fuel compact with ordinal graphite/carbon matrix. All dummy coated fuel particles were held in specimen after 10 h oxidation.
Sawa, Kazuhiro; Yamashita, Toshiyuki; Minato, Kazuo; Arai, Yasuo; Konashi, Kenji*
Nihon Genshiryoku Gakkai-Shi, 44(9), p.657 - 662, 2002/09
no abstracts in English
Komori, Yoshihiro
Saishin Kaku Nenryo Kogaku; Kodoka No Genjo To Tembo, p.241 - 250, 2001/06
no abstracts in English
Ugajin, Mitsuhiro; Shiba, Koreyuki
Journal of Nuclear Materials, 74(3), p.354 - 357, 1978/03
Times Cited Count：0no abstracts in English
Nihon Genshiryoku Gakkai-Shi, 18(4), p.202 - 207, 1976/04
no abstracts in English
Ueta, Shohei; Aihara, Jun; Sumita, Junya; Shaimerdenov, A.*; Dyussambayev, D.*; Gizatulin, S.*; Chakrov, P.*; Sakaba, Nariaki
no journal, ,
In order to investigate irradiation performance of the newly-designed high temperature gas-cooled reactor (HTGR) fuel for high burnup around 100 GWd/t, a capsule irradiation test has been carried out by WWR-K research reactor in the Institute of Nuclear Physics (INP) of Kazakhstan. A result on evaluation of the fuel integrity based on the fractional release of fission product (FP) released from the fuel during the irradiation and a plan of post-irradiation examination are reported.
Yamamoto, Takenori*; Tojo, Takuya*; Kuroda, Masatoshi*; Sumita, Junya; Aihara, Jun; Tachibana, Yukio
no journal, ,
R&D on SiC/C mixed matrix fuel element of high temperature gas-cooled reactors (HTGRs) to improve oxidation resistance of fuel has been started. In this R&D, Young's modulus of fabricated SiC/C mixed matrix dummy fuel elements was measured. In addition, set of fabrication conditions of SiC/C mixed matrix dummy fuel elements was decided for modeling of relationship between fabrication condition and strength of fabricated SiC/C mixed matrix dummy fuel elements to estimate fabrication condition for SiC/C mixed matrix fuel elements with high strength.
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.
Sasaki, Koei
no journal, ,
"Design of high burnup fuel for HTGR" was instructed for "3rd Seminar on Development of HTGR Technology for Cogeneration and Heat Applications" as a part of "Implementing Agreement between the Japan Atomic Energy Agency and National Centre for Nuclear Research in the Republic of Poland for cooperation in research and development in the field of high temperature gas-cooled reactor technologies".
Sasaki, Koei
no journal, ,
We are developing a fuel coating material with a Cs capture function in anticipation of reducing the exposure dose of HTGR plants, improving safety in the event of a primary reactor accident, making the plant more compact and reducing construction costs due to the reduction of shielding wall thickness. Bi and Sb were selected as Cs getter materials. Their simulated Cs trap compounds were formed in the carbon structure and high temperature stability at 1500C was evaluated. Although Bi was precipitated in carbon, the formation of Cs compounds could not be seen. Sb formed a Cs compound (CsSb, etc.) in carbon structure and showed stability at 1500C. Therefore, it was found that Sb has a Cs trap function.
Haseda, Masaya*; Aihara, Jun; Sawa, Kazuhiro*
no journal, ,
Failure probability of coated fuel particles (CFPs) of high temperature gas-cooled reactors (HTGRs) under irradiation is strongly dependent on irradiation characters of pyrolytic carbon (PyC) layers of CFPs. But it is very difficult to newly obtain irradiation data of PyC layers with experiments. Therefore, in the past study, it was suggested to calculate failure probabilities based on a report summarizing irradiation data obtained at various irradiation temperatures of PyC layers of various Bacon anisotropy factor (BAF), and on result of failure probability measurement of irradiation test of the High Temperature Engineering Test Reactor (HTTR) fuel. Then a BAF of PyC layers of Japanese CFPs was suggested to use to calculate failure probability of Japanese CFPs. In this study, it was clarified that the failure probability calculated under condition of an irradiation test of Japanese CFPs other than above one, and using above BAF does not fit the experimental result.
Kawano, Kaito*; Aihara, Jun; Sawa, Kazuhiro*
no journal, ,
Failure probability of coated fuel particles (CFPs) of high temperature gas-cooled reactors (HTGRs) under irradiation is strongly dependent on irradiation characters of pyrolytic carbon (PyC) layers of CFPs. But it is very difficult to newly obtain irradiation data of PyC layers with experiments. Therefore, in the past study, it was suggested to calculate failure probabilities based on a report summarizing irradiation data obtained at various irradiation temperatures of PyC layers of various Bacon anisotropy factor (BAF), and on result of failure probability measurement of irradiation test of the High Temperature Engineering Test Reactor (HTTR) fuel. Then a BAF of PyC layers of Japanese CFPs was suggested to use to calculate failure probability of Japanese CFPs. In this study, the failure probability was carried out under high burnup condition compared to the HTTR.
