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JAEA Reports

Achievement of safety demonstration tests using HTTR; Loss of forced cooling test at 100% reactor power (30 MW)

Nagasumi, Satoru; Hasegawa, Toshinari; Nakagawa, Shigeaki; Kubo, Shinji; Iigaki, Kazuhiko; Shinohara, Masanori; Saikusa, Akio; Nojiri, Naoki; Saito, Kenji; Furusawa, Takayuki; et al.

JAEA-Research 2025-005, 23 Pages, 2025/07

JAEA-Research-2025-005.pdf:2.68MB

A safety demonstration test under abnormal operating conditions using the HTTR (High Temperature Engineering Test Reactor) was conducted to demonstrate safety features of the HTGRs (High Temperature Gas-cooled Reactors). Under a simulation of a control rod shutdown failure, all primary helium gas circulators were intentionally stopped during a steady-state operation at 100% reactor thermal power (30 MW), temporal changes of the reactor power and temperatures around the reactor pressure vessel (RPV) were obtained after the complete loss of forced heat removal from the reactor core. After the event (primary coolant flow stopped), the reactor power quickly decreased due to the negative reactivity feedback associated with the core temperature rise, and then the reactor power spontaneously shifted to a stable state of low power (about 1.2%) even after a recriticality. Heat dissipation from RPV surface to a surrounding vessel cooling system (water-cooled panels) ensured the amount of heat removal required to maintain the reactor temperature constant in the low power state. In this way, the transition from the event occurrence to the stable and safety state, i.e., inherent safety features of HTGRs, were demonstrated in the case of core forced cooling loss without active shutdown operations.

Journal Articles

Characterization of the thorium-229 defect structure in CaF$$_{2}$$ crystals

Takatori, Sayuri*; Pimon, M.*; Pollitt, S.*; Bartokos, M.*; Beeks, K.*; Gr$"u$neis, A.*; Hiraki, Takahiro*; Homma, Tetsuo*; Hosseini, N.*; Leitner, A.*; et al.

New Journal of Physics (Internet), 27(4), p.043024_1 - 043024_10, 2025/04

https://doi.org/10.1088/1367-2630/adce22
 Times Cited Count：5 Percentile：76.34(Physics, Multidisciplinary)

Recent reports on laser excitation of the low-energy thorium-229 ($$^{229}$$Th) nuclear isomeric state in calcium fluoride single crystals render this system a promising candidate for a solid-state nuclear clock. However, experimental characterization of the microscopic ion arrangement around the doped $$^{229}$$Th and its electronic charge state, crucial for the precise control of the clock transition and assessing the solid-state clock's performance, remains an unresolved task. This study uses X-ray absorption fine structure spectroscopy of $$^{229}$$Th:CaF$$_{2}$$ to investigate the charge state and coordination environment of doped $$^{229}$$Th. The results indicate that $$^{229}$$Th is doped with a 4+ valence at the substitutional site of the Ca$$^{2+}$$ ion, with charge compensated provided by two F$$^{-}$$ ions located at interstitial sites adjacent to $$^{229}$$Th.

Journal Articles

Crystal structural analysis of solid oxide fuel cells using the synchrotron X-ray and neutron diffraction method

Ito, Takanori*; Igawa, Naoki; Homma, Tetsuo*

Supuringu-8 No Kokido Hoshako O Riyoshita Gurin Enerugi Bunya Niokeru Denchi Kaihatsu, p.104 - 112, 2014/02

Functional materials consist of many elements and therefore have complex crystal structure. Synchrotron X-ray and neutron scattering facilities are powerful tools to investigate the crystal structural information of those materials. Here we make an introduction to the crystal analysis method by the synchrotron X-ray and neutron diffraction applying to the solid oxide fuel cells.

Journal Articles

In-vessel tritium

Ueda, Yoshio*; Oya, Kaoru*; Ashikawa, Naoko*; Ito, Atsushi*; Ono, Tadayoshi*; Kato, Daiji*; Kawashima, Hisato; Kawamura, Gakushi*; Kenmotsu, Takahiro*; Saito, Seiki*; et al.

Purazuma, Kaku Yugo Gakkai-Shi, 88(9), p.484 - 502, 2012/09

http://ci.nii.ac.jp/naid/110009518478

no abstracts in English

Journal Articles

Recent progress in the energy recovery linac project in Japan

Sakanaka, Shogo*; Akemoto, Mitsuo*; Aoto, Tomohiro*; Arakawa, Dai*; Asaoka, Seiji*; Enomoto, Atsushi*; Fukuda, Shigeki*; Furukawa, Kazuro*; Furuya, Takaaki*; Haga, Kaiichi*; et al.

Proceedings of 1st International Particle Accelerator Conference (IPAC '10) (Internet), p.2338 - 2340, 2010/05

http://accelconf.web.cern.ch/AccelConf/IPAC10/papers/tupe091.pdf

Future synchrotron light source using a 5-GeV energy recovery linac (ERL) is under proposal by our Japanese collaboration team, and we are conducting R&D efforts for that. We are developing high-brightness DC photocathode guns, two types of cryomodules for both injector and main superconducting (SC) linacs, and 1.3 GHz high CW-power RF sources. We are also constructing the Compact ERL (cERL) for demonstrating the recirculation of low-emittance, high-current beams using above-mentioned critical technologies.

Journal Articles

Element and orbital-specific observation of two-step magnetic transition in NpNiGa$$_5$$; X-ray magnetic circular dichroism study

Okane, Tetsuo; Okochi, Takuo*; Inami, Toshiya; Takeda, Yukiharu; Fujimori, Shinichi; Kawamura, Naomi*; Suzuki, Motohiro*; Tsutsui, Satoshi*; Yamagami, Hiroshi; Fujimori, Atsushi; et al.

Physical Review B, 80(10), p.104419_1 - 104419_7, 2009/09

https://doi.org/10.1103/PhysRevB.80.104419
 Times Cited Count：6 Percentile：27.70(Materials Science, Multidisciplinary)

Journal Articles

Resonant X-ray magnetic diffraction experiments on SmB$$_2$$C$$_2$$

Inami, Toshiya; Homma, Tetsuo*; Tsutsui, Satoshi*; Indo, Kentaro*; Onodera, Hideya*; Ishii, Kenji; Owada, Kenji; Kuzushita, Kaori*; Nakao, Hironori*; Murakami, Yoichi*

Journal of Magnetism and Magnetic Materials, 310(2, Part1), p.748 - 750, 2007/03

We investigated successive phase transitions in SmB$$_2$$C$$_2$$ at $$T_{rm N2}$$=37K and $$T_{rm N1}$$=51K by means of resonant X-ray diffraction. Strong resonant diffraction signal is observed at the 101 reflection below $$T_{rm N2}$$ at the Sm $$L_3$$ edge, whereas in the intermediate phase signals appear at incommensurate positions $${vec Q}$$=(1$$pmdelta$$, $$pmdelta$$,1) where $$delta$$=0.13. Accordingly, the successive phase transitions in SmB$$_2$$C$$_2$$ is found to be commensurate-to-incommensurate magnetic phase transitions.

Journal Articles

Development of equipment to remove cadmium from waste of scallop processing by graft adsorbent

Nakai, Hisaaki*; Temma, Tsuyoshi*; Tamada, Masao; Sawamura, Toshihiro*; Saito, Takayuki*; Homma, Tetsuo*; Sato, Yasushi*

JAEA-Review 2006-042, JAEA Takasaki Annual Report 2005, P. 47, 2007/02

https://jopss.jaea.go.jp/pdfdata/JAEA-Review-2006-042.pdf

Removal technology for cadmium ion (Cd$$^{2+}$$) from the mid-gut gland in the scallop processing was developed by combining the Cd$$^{2+}$$ leaching process with malic acid solution and Cd$$^{2+}$$ adsorption with iminodiacetic acid adsorbent synthesized with radiation-induced graft polymerization. Experimental equipment was assembled for removal of the Cd$$^{2+}$$ from 20-40 kg of mid-gut gland. The Cd$$^{2+}$$ in the mid-gut gland was reduced from 25 mg/kg to 1 mg/kg after 24 h treatment.

Journal Articles

Soft X-ray absorption magnetic circular dichroism study of ferromagnetic superconductor UGe$$_2$$

Okane, Tetsuo; Okamoto, Jun*; Mamiya, Kazutoshi*; Fujimori, Shinichi; Takeda, Yukiharu; Saito, Yuji; Muramatsu, Yasuji*; Fujimori, Atsushi*; Haga, Yoshinori; Yamamoto, Etsuji; et al.

Journal of the Physical Society of Japan, 75(2), p.024704_1 - 024704_5, 2006/02

https://doi.org/10.1143/JPSJ.75.024704
 Times Cited Count：12 Percentile：57.03(Physics, Multidisciplinary)

no abstracts in English

Journal Articles

$$^{238}$$U M$"o$ssbauer study on the 5f-quadrupoles in uranium-based intermetallics

Tsutsui, Satoshi*; Nakada, Masami; Nasu, Saburo*; Homma, Tetsuo*; Tokiwa, Yoshifumi; Aoki, Dai*; Wisniewski, P.*; Haga, Yoshinori; Onuki, Yoshichika

Hyperfine Interactions, 141/142(1-4), p.237 - 242, 2002/06

https://doi.org/10.1023/A:1021281315015
 Times Cited Count：2 Percentile：14.62(Physics, Atomic, Molecular & Chemical)

We have determined the distribution of the 5f-quadrupoles and detected the 5f-quadrupole order in the uranium intermetallics, uranium dipnictides and UPd$$_3$$, with $$^{238}$$ Mo"ssbauer spectroscopy. We have declared that the distribution of the 5f-quadrupoles depends on the magnetic sequence in uranium dipnictides. The distribution of the 5f-quadrupole is spherical in UBi$$_2$$, while those are oblate within c-plane in UP$$_2$$, UAs$$_2$$ and USb$$_2$$. We have observed the sudden drop of the recoil-free fraction above the transition temperature of the quadrupole order in UPd$$_3$$. The present result suggests the change of the phonon states due to the quadrupole order in this compound.

Journal Articles

$$^{238}$$U M$"o$ssbauer spectroscopic study of UX$$_{2}$$(X=Ga, P, As, Sb)

Tsutsui, Satoshi; Nakada, Masami; Nasu, Saburo*; Haga, Yoshinori; Homma, Tetsuo; Yamamoto, Etsuji; Tokiwa, Yoshifumi; Aoki, Dai*; Wi$'s$niewski, P.*; Onuki, Yoshichika

Journal of the Physical Society of Japan, Vol.70, Supplement A, p.34 - 36, 2001/05

no abstracts in English

Journal Articles

$$^{238}$$U M$"o$ssbauer study on the magnetic properties of uranium-based heavy fermion superconductors

Tsutsui, Satoshi; Nakada, Masami; Nasu, Saburo*; Haga, Yoshinori; Homma, Tetsuo; Yamamoto, Etsuji; Okuni, Hitoshi*; Onuki, Yoshichika

Hyperfine Interactions, 126(1-4), p.335 - 340, 2000/07

https://doi.org/10.1023/A:1012626913681
 Times Cited Count：6 Percentile：37.14(Physics, Atomic, Molecular & Chemical)

no abstracts in English

Journal Articles

De Haas-van Alphen effect in a heavy fermion superconductor UPd$$_{2}$$Al$$_{3}$$

Haga, Yoshinori; Inada, Yoshihiko*; Sakurai, Kenji*; Tokiwa, Yoshifumi; Yamamoto, Etsuji; Homma, Tetsuo*; Onuki, Yoshichika*

Physica B; Condensed Matter, 284-288, p.1291 - 1292, 2000/07

https://doi.org/10.1016/S0921-4526(99)02566-1
 Times Cited Count：0 Percentile：0.00(Physics, Condensed Matter)

no abstracts in English

Journal Articles

The Basal-plane anisotropy in the paramagnetic state in UPd$$_{2}$$Al$$_{3}$$

Haga, Yoshinori; Yamamoto, Etsuji; Homma, Tetsuo*; Onuki, Yoshichika*

Physica B; Condensed Matter, 284-288, p.1289 - 1290, 2000/07

https://doi.org/10.1016/S0921-4526(99)02564-8
 Times Cited Count：0 Percentile：0.00(Physics, Condensed Matter)

no abstracts in English

Journal Articles

Observation of heavy electrons in UPd$$_{2}$$Al$$_{3}$$

Haga, Yoshinori; Inada, Yoshihiko*; Yamagami, Hiroshi*; Sakurai, Kenji*; Tokiwa, Yoshifumi; Yamamoto, Etsuji; Homma, Tetsuo*; Onuki, Yoshichika*

Physica B; Condensed Matter, 281-282, p.780 - 781, 2000/06

https://doi.org/10.1016/S0921-4526(99)01095-9
 Times Cited Count：0 Percentile：0.00(Physics, Condensed Matter)

no abstracts in English

Journal Articles

Neutron scattering studies on heavy fermion superconductors

Metoki, Naoto; Koike, Yoshihiro; Haga, Yoshinori; Yamamoto, Etsuji; Homma, Tetsuo; Onuki, Yoshichika; Kimura, Noriaki*; Maezawa, Kunio*

Physica B; Condensed Matter, 281-282, p.987 - 988, 2000/06

https://doi.org/10.1016/S0921-4526(99)00905-9
 Times Cited Count：1 Percentile：8.09(Physics, Condensed Matter)

no abstracts in English

Journal Articles

$$^{238}$$U M$"o$ssbauer spectrosopic study of UPd$$_{2}$$Al$$_{3}$$ and URu$$_{2}$$Si$$_{2}$$

Tsutsui, Satoshi; Nakada, Masami; Nasu, Saburo*; Haga, Yoshinori; Homma, Tetsuo; Yamamoto, Etsuji; Okuni, Hitoshi*; Onuki, Yoshichika

Physica B; Condensed Matter, 281-282, p.242 - 243, 2000/06

https://doi.org/10.1016/S0921-4526(99)01080-7
 Times Cited Count：3 Percentile：21.29(Physics, Condensed Matter)

no abstracts in English

Journal Articles

Magnetic, elastic, transport and fermi surface properties of a ferromagnetic compound UGa$$_{2}$$

Homma, Tetsuo; Yamamoto, Etsuji; Haga, Yoshinori; Settai, Rikio*; Araki, Shingo*; Inada, Yoshihiko*; Takeuchi, Tetsuya*; Kuwahara, Keitaro*; Amitsuka, Hiroshi*; Sakakibara, T.*; et al.

Physica B; Condensed Matter, 281-282, p.195 - 196, 2000/06

https://doi.org/10.1016/S0921-4526(99)01114-X
 Times Cited Count：2 Percentile：14.96(Physics, Condensed Matter)

no abstracts in English

Journal Articles

Fermi surface of UB$$_{4}$$ studied by the de Haas-van Alphen oscillation and magnetoresistance experiments

Yamamoto, Etsuji; Homma, Tetsuo; Haga, Yoshinori; Inada, Yoshihiko*; Aoki, Dai*; Tokiwa, Yoshifumi; Suzuki, N.*; Miyake, Kosaku*; Onuki, Yoshichika

Physica B; Condensed Matter, 281-282, p.767 - 768, 2000/06

https://doi.org/10.1016/S0921-4526(99)01096-0
 Times Cited Count：1 Percentile：8.09(Physics, Condensed Matter)

no abstracts in English

Journal Articles

Neutron scattering studies on heavy-fermion superconductors

Metoki, Naoto; Koike, Yoshihiro; Haga, Yoshinori; Homma, Tetsuo; Sato, Masugu; Onuki, Yoshichika

Physica B; Condensed Matter, 280(1-4), p.362 - 367, 2000/05

https://doi.org/10.1016/S0921-4526(99)01746-9
 Times Cited Count：3 Percentile：21.29(Physics, Condensed Matter)

no abstracts in English

35 (Records 1-20 displayed on this page)