Thermal conductivity measurement of uranium-plutonium mixed oxide doped with Nd/Sm as simulated fission products

Horii, Yuta; Hirooka, Shun; Uno, Hiroki*; Ogasawara, Masahiro*; Tamura, Tetsuya*; Yamada, Tadahisa*; Furusawa, Naoya*; Murakami, Tatsutoshi; Kato, Masato

Journal of Nuclear Materials, 588, p.154799_1 - 154799_20, 2024/01

https://doi.org/10.1016/j.jnucmat.2023.154799

The thermal conductivities of near-stoichiometric (U,Pu,Am)O doped with NdO/SmO, which is major fission product (FP) generated by a uranium-plutonium mixed oxides (MOX) fuel irradiation, as simulated fission products are evaluated at 1073-1673 K. The thermal conductivities are calculated from the thermal diffusivities that are measured using the laser flash method. To evaluate the thermal conductivity from a homogeneity viewpoint of Nd/Sm cations in MOX, the specimens with different homogeneity of Nd/Sm are prepared using two kinds of powder made by ball-mill and fusion methods. A homogeneous Nd/Sm distribution decreases the thermal conductivity of MOX with increasing Nd/Sm content, whereas heterogeneous Nd/Sm has no influence. The effect of Nd/Sm on the thermal conductivity is studied using the classical phonon transport model (A+BT). The dependences of the coefficients A and B on the Nd/Sm content (C and C, respectively) are evaluated as: A(mK/W)=1.70 10 + 0.93C + 1.20C, B(m/W)=2.39 10.

Water contents in aggregates and cement pastes determined by gravimetric analysis and prompt -ray analysis

Kinoshita, Norikazu*; Noto, Takuma*; Nakajima, Hitoshi*; Kosako, Kazuaki*; Kato, Takahiro*; Kuroiwa, Yoichi*; Kurabe, Misako*; Sasaki, Yuki*; Torii, Kazuyuki*; Maeda, Makoto; et al.

Journal of Radioanalytical and Nuclear Chemistry, 332(2), p.479 - 486, 2023/02

https://doi.org/10.1007/s10967-023-08776-w

Design and actual performance of J-PARC 3 GeV rapid cycling synchrotron for high-intensity operation

Yamamoto, Kazami; Kinsho, Michikazu; Hayashi, Naoki; Saha, P. K.; Tamura, Fumihiko; Yamamoto, Masanobu; Tani, Norio; Takayanagi, Tomohiro; Kamiya, Junichiro; Shobuda, Yoshihiro; et al.

Journal of Nuclear Science and Technology, 59(9), p.1174 - 1205, 2022/09

https://doi.org/10.1080/00223131.2022.2038301

In the Japan Proton Accelerator Research Complex, the purpose of the 3 GeV rapid cycling synchrotron (RCS) is to accelerate a 1 MW, high-intensity proton beam. To achieve beam operation at a repetition rate of 25 Hz at high intensities, the RCS was elaborately designed. After starting the RCS operation, we carefully verified the validity of its design and made certain improvements to establish a reliable operation at higher power as possible. Consequently, we demonstrated beam operation at a high power, namely, 1 MW. We then summarized the design, actual performance, and improvements of the RCS to achieve a 1 MW beam.

Electronic effects of nitrogen atoms of supports on Pt-Ni rhombic dodecahedral nanoframes for oxygen reduction

Kato, Masaru*; Nakahoshiba, Ryota*; Ogura, Kazuya*; Tokuda, Shoichi*; Yasuda, Satoshi; Higashi, Kotaro*; Uruga, Tomoya*; Uemura, Yohei*; Yagi, Ichizo*

ACS Applied Energy Materials (Internet), 3(7), p.6768 - 6774, 2020/07

https://doi.org/10.1021/acsaem.0c00903

To understand electronic effects of nitrogen-doped and polymer-coated carbon supports on the catalytic activity of Pt-based nanostructured catalysts, we prepared PtNi nanoframes (NFs) supported on polybenzimidazole (PBI)-coated and uncoated carbon nanotubes for the oxygen reduction reaction (ORR), and then compared their catalytic activities and electronic properties with those of NFs immobilized on nitrogen-doped and undoped carbon supports. Although both PBI-coating and nitrogen-doping approaches improved the catalytic activity of NFs, X-ray photoelectron spectroscopy and X-ray absorption spectroscopy revealed that nitrogen doping showed electronic effects on NFs, whereas PBI-coating showed almost no impact on the electronic state of NFs but stabilized Pt(OH) species under electrochemical conditions. Our studies demonstrate that difference in microscopic environments of nitrogen atoms at the catalyst/support interface is highly sensitive to the electronic effects of supports on Pt-based electrocatalysts.

Incorporation of multinuclear copper active sites into nitrogen-doped graphene for electrochemical oxygen reduction

Kato, Masaru*; Muto, Marika*; Matsubara, Naohiro*; Uemura, Yohei*; Wakisaka, Yuki*; Yoneuchi, Tsubasa*; Matsumura, Daiju; Ishibara, Tomoko*; Tokushima, Takashi*; Noro, Shinichiro*; et al.

ACS Applied Energy Materials (Internet), 1(5), p.2358 - 2364, 2018/05

https://doi.org/10.1021/acsaem.8b00491

Benchmarking of economic evaluation models for an advanced loop-type sodium cooled fast reactor

Mukaida, Kyoko; Kato, Atsushi; Shiotani, Hiroki; Hayafune, Hiroki; Ono, Kiyoshi

Nuclear Engineering and Design, 324, p.35 - 44, 2017/12

https://doi.org/10.1016/j.nucengdes.2017.08.011

An economic calculation model based on detailed mass-flow (the JAEA model) was developed for the comprehensive evaluation of an advanced loop-type sodium-cooled fast reactor cycle system (SFR) designed in the FaCT project. The JAEA model enables calculation of the processing amount and its composition in each facility by simulating mass-flow, and has function to evaluate economics based on the processing amount. In this report, to identify the difference in evaluation methods between the JAEA model and an internationally-authorized code, and verify its calculation functions, the generation cost of SFR system was evaluated using the JAEA model and the G4-ECONS. Consequently, it was clarified that the JAEA model is influenced to higher degree by the discount rate. When the present value was not taken into account, the results of both methods were quite similar, but it was found that the sensitivity of the load factor is relatively larger the G4-ECONS than in the JAEA model.

Platinum nanoparticles on the glassy carbon surface irradiated with argon ions

Kimata, Tetsuya*; Kato, Sho*; Yamaki, Tetsuya; Yamamoto, Shunya; Kobayashi, Tomohiro*; Terai, Takayuki*

Surface & Coatings Technology, 306(Part A), p.123 - 126, 2016/11

https://doi.org/10.1016/j.surfcoat.2016.05.042

Platinum (Pt) nanoparticle catalysts with oxygen reduction reaction (ORR) activity are required for practical applications of polymer electrolyte fuel cells. We prepared Pt nanoparticles on an Ar-irradiated glassy carbon (GC) surface by a radio-frequency magnetron sputtering method to investigate the influence of the ion-induced lattice defects in GC on the ORR activity of the deposited Pt nanoparticles. Interestingly, the Pt nanoparticles on the irradiated surface exhibited ca. 2.5 times higher specific activity than those on the non-irradiated one. X-ray photoelectron spectroscopy suggested the interfacial Pt-C interaction occurring between the irradiated GC and Pt nanoparticles, which should be a reason for improvement of the ORR activity.

Angle-resolved photoemission analysis of electronic structures for thermoelectric properties of off-stoichiometric FeVAl alloys

Soda, Kazuo*; Harada, Shota*; Hayashi, Toshimitsu*; Kato, Masahiko*; Ishikawa, Fumihiro*; Yamada, Yu*; Fujimori, Shinichi; Saito, Yuji

Materials Transactions, 57(7), p.1040 - 1044, 2016/06

https://doi.org/10.2320/matertrans.MF201603

Safety improvement in building layout design to meet the safety design criteria for the Generation IV SFR

Kato, Atsushi; Chikazawa, Yoshitaka; Nabeshima, Kunihiko; Iwasaki, Mikinori*; Akiyama, Yo*; Oya, Takeaki*

Proceedings of 2015 International Congress on Advances in Nuclear Power Plants (ICAPP 2015) (CD-ROM), p.593 - 600, 2015/05

Japan sodium cooled fast reactor is the advanced loop type reactor developing in Japan. After the Fukushima-Dai-ichi NPP accident, system enhancement against severe accident have been investigated mainly for residual decay heat removal system, spent fuel storage system and emergency power sources in order to satisfy the safety design criteria for Generation IV SFR. This paper describes principle of the building layout design and the actual approach to be consistent with the recent design enhancement in JSFR. From the perspective of greater ability to withstand severe events, the principles of the building layout design as the measures against aircraft attack and the consequential fire, and tsunami are introduced in order to avoid local event initiating and simultaneous redundant failure of the safety grade facilities and could achieve lowering risk of the loss of all stuck and maintaining the essential power supply.

Annual report of Nuclear Emergency Assistance and Training Center (April 1, 2013 - March 31, 2014)

Sato, Takeshi; Muto, Shigeo; Akiyama, Kiyomitsu; Aoki, Kazufumi; Okamoto, Akiko; Kawakami, Takeshi; Kume, Nobuhide; Nakanishi, Chika; Koie, Masahiro; Kawamata, Hiroyuki; et al.

JAEA-Review 2014-048, 69 Pages, 2015/02

JAEA-Review-2014-048.pdf:13.91MB

JAEA was assigned as a designated public institution under the Disaster Countermeasures Basic Act and under the Armed Attack Situations Response Act. Based on these Acts, the JAEA has the responsibility of providing technical support to the national government and/or local governments in case of disaster responses or response in the event of a military attack, etc. In order to fulfill the tasks, the JAEA has established the Emergency Action Plan and the Civil Protection Action Plan. In case of a nuclear emergency, NEAT dispatches specialists of JAEA, supplies the national government and local governments with emergency equipment and materials, and gives technical advice and information. In normal time, NEAT provides various exercises and training courses concerning nuclear disaster prevention to those personnel taking an active part in emergency response institutions of the national and local governments, police, fire fighters, self-defense forces, etc. in addition to the JAEA itself. The NEAT also researches nuclear disaster preparedness and response, and cooperates with international organizations. In the FY2013, the NEAT accomplished the following tasks: (1) Technical support activities as a designated public institution in cooperation with the national and local governments, etc. (2) Human resource development, exercise and training of nuclear emergency response personnel for the national and local governments, etc. (3) Researches on nuclear disaster preparedness and response, and sending useful information (4) International contributions to Asian countries on nuclear disaster preparedness and response in collaboration with the international organizations