Tsubakihara, Kosuke*; Okumura, Shin*; Ishizuka, Chikako*; Yoshida, Tadashi*; Minato, Futoshi; Chiba, Satoshi*
Journal of Nuclear Science and Technology, 58(2), p.151 - 165, 2021/02
Ekawa, Hiroyuki; Ashikaga, Sakiko; Hasegawa, Shoichi; Hashimoto, Tadashi; Hayakawa, Shuhei; Hosomi, Kenji; Ichikawa, Yudai; Imai, Kenichi; Kimbara, Shinji*; Nanamura, Takuya; et al.
Progress of Theoretical and Experimental Physics (Internet), 2019(2), p.021D02_1 - 021D02_11, 2019/02
Koura, Hiroyuki; Yoshida, Tadashi*; Tachibana, Takahiro*; Chiba, Satoshi*
JAEA-Conf 2017-001, p.205 - 210, 2018/01
no abstracts in English
Chiba, Satoshi*; Wakabayashi, Toshio*; Tachi, Yoshiaki; Takaki, Naoyuki*; Terashima, Atsunori*; Okumura, Shin*; Yoshida, Tadashi*
Scientific Reports (Internet), 7(1), p.13961_1 - 13961_10, 2017/10
Transmutation of long-lived fission products (LLFPs: Se, Zr, Tc, Pd, I, and Cs) into short-lived or non-radioactive nuclides by fast neutron spectrum reactors without isotope separation has been proposed as a solution to the problem of radioactive wastes disposal. Despite investigation of many methods, such transmutation remains technologically difficult. To establish an effective and efficient transmutation system, we propose a novel neutron moderator material, yttrium deuteride (YD), to soften the neutron spectrum leaking from the reactor core. Neutron energy spectra and effective half-lives of LLFPs, transmutation rates, and support ratios were evaluated with the continuous-energy Monte Carlo code MVP-II/MVP-BURN and the JENDL-4.0 cross section library. With the YD moderator in the radial blanket and shield regions, effective half-lives drastically decreased from 10 to 10 years and the support ratios reached 1.0 for all six LLFPs. This successful development and implementation of a transmutation system for LLFPs without isotope separation contribute to developing a self-consuming cycle of LLFPs using fast spectrum reactors to reduce radioactive waste.
Koura, Hiroyuki; Yoshida, Tadashi*; Tachibana, Takahiro*; Chiba, Satoshi*
EPJ Web of Conferences, 146, p.12003_1 - 12003_4, 2017/09
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 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
Wakimoto, Shuichi; Ishii, Kenji; Kimura, Hiroyuki*; Ikeuchi, Kazuhiko*; Yoshida, Masahiro*; Adachi, Tadashi*; Casa, D.*; Fujita, Masaki*; Fukunaga, Yasushi*; Gog, T.*; et al.
Physical Review B, 87(10), p.104511_1 - 104511_7, 2013/03
Yoshida, Kazuhiro*; Sakata, Hideyuki*; Sago, Hiromi*; Shiraishi, Tadashi*; Oyama, Kazuhiro*; Hagiwara, Hiroyuki*; Yamano, Hidemasa; Yamamoto, Tomohiko
Proceedings of 8th Japan-Korea Symposium on Nuclear Thermal Hydraulics and Safety (NTHAS-8) (USB Flash Drive), 9 Pages, 2012/12
To prevent the vortex cavitations, asymmetric flow in the upper plenum due to the radial slit with upper internal structure (UIS) has been mitigated by installing a cylindrical structure named as dummy plug instead of the fuel handling machine only used for refueling period. In this study, the extended brim and the division plate at the slit of UIS have been proposed in order to improve flow pattern in upper plenum for the purpose of the vortex cavitation prevention.
Yoshida, Atsuro*; Higashi, Yuma*; Narabayashi, Tadashi*; Khoo Chong Weng, W.*; Arae, Kunihiko*; Tsuji, Masashi*; Ohshima, Hiroyuki; Kurihara, Akikazu
Proceedings of 19th International Conference on Nuclear Engineering (ICONE-19) (CD-ROM), 8 Pages, 2011/10
One of the design basis accidents in sodium-cooled fast reactor is sodium-water reaction at steam generator (SG). In case of a defect occurred on a heat transfer tube, the high-pressure water/vapor will spout into the low-pressure sodium surrounding outside the tube. As sodium is ordinarily quite reactive with water, this will initiate sodium-water reactions accompanied by high chemical heat generation. The liquid droplet in the reaction steam outflow would impinge on neighboring tubes to cause erosion, while the chemical reaction will cause corrosion, eventually may lead to secondary tube failure. Focusing on the erosion part, this study is to evaluate the liquid droplet impingement erosion (LDIE) rate on neighboring tubes caused by SG heat transfer tube rupture. In this paper, as a basic study, the pressure and temperature distribution of high -pressure two-phase free jet into the air is measured.
Yoshikawa, Hiroshi; Sakaki, Hironao; Sako, Hiroyuki; Takahashi, Hiroki; Shen, G.; Kato, Yuko; Ito, Yuichi; Ikeda, Hiroshi*; Ishiyama, Tatsuya*; Tsuchiya, Hitoshi*; et al.
Proceedings of International Conference on Accelerator and Large Experimental Physics Control Systems (ICALEPCS '07) (CD-ROM), p.62 - 64, 2007/10
J-PARC is a large scale facility of the proton accelerators for the multi-purpose of scientific researches in Japan. This facility consists of three accelerators and three experimental stations. Now, J-PARC is under construction, and LINAC is operated for one year, 3GeV synchrotron has just started the commissioning in this October the 1st. The completion of this facility will be next summer. The control system of accelerators established fundamental performance for the initial commissioning. The most important requirement to the control system of this facility is to minimize the activation of accelerator devices. In this paper, we show that the performances of each layer of this control system have been achieved in the initial stage.
Yoshida, Yuichiro*; Okuri, Takatoshi*; Takeda, Chika*; Kuroki, Ryota; Izuhara, Kenji*; Imoto, Taiji*; Ueda, Tadashi*
Biochemical and Biophysical Research Communications, 358(1), p.292 - 297, 2007/06
The single nucleotide polymorphism interleukin-13 (IL-13) R110Q is associated with severe bronchial asthma because its lower affinity leads to the augmentation of local IL-13 concentration, resulting in an increase in the signal transduction via IL-13R. Since the mutation site does not directly bind to IL-13 R2, we carried out NMR relaxation analyses of the wild-type IL-13 and IL-13 R110Q in order to examine whether the R110Q mutation affects the internal motions in IL-13 molecules. The results showed that the internal motion in the micro- to millisecond time scale on helix D, which is suggested to be important for the interaction between IL-13 and IL-13R2, is increased in IL-13-R110Q compared with that in the wild-type IL-13. It therefore appears that the difference in the internal motions on helix D between the wild-type IL-13 and IL-13-R110Q may be involved in their affinity differences with IL-13R2.
Matsuda, Makoto; Takeuchi, Suehiro; Tsukihashi, Yoshihiro; Hanashima, Susumu; Abe, Shinichi; Osa, Akihiko; Ishizaki, Nobuhiro; Tayama, Hidekazu; Nakanoya, Takamitsu; Kabumoto, Hiroshi; et al.
Dai-19-Kai Tandemu Kasokuki Oyobi Sono Shuhen Gijutsu No Kenkyukai Hokokushu, p.9 - 12, 2007/01
no abstracts in English
Narita, Tadashi*; Enomoto, Kazuyuki*; Maekawa, Yasunari; Yoshida, Masaru; Ichikawa, Mitsuru*; Hamana, Hiroshi*
Journal of Fluorine Chemistry, 128(1), p.52 - 54, 2007/01
Perfluorinated polymers have expected to be the key materials for fuel cell membranes owing to the high chemical stability, thermo-durability and optical property. However, a homopolymer of FVPE has never yielded under usual polymerization conditions and alternating copolymers with several non-fluorinated vinyl monomers have only been reported. Thus, using radiation-induced polymerization, in which initiating species (radicals) can be continuously produced, the polymerization of trifluorovinyl heptafluoropropyl ether (FVPE) was examined to afford high molecular weight polymers of FVPE. The formation of FVPE homopolymers was confirmed by NMR and IR spectroscopy.
Enomoto, Kazuyuki*; Moon, S.*; Maekawa, Yasunari; Shimoyama, Junji*; Goto, Kazuyuki*; Narita, Tadashi*; Yoshida, Masaru
Journal of Vacuum Science and Technology B, 24(5), p.2337 - 2349, 2006/09
The electron beam (EB)-induced reaction of triphenylsulfonium methanesulfonate (1-Ms) in the solid state afforded the benzene-substituted product, biphenyldiphenylsulfonium methanesulfonate (2-Ms), which has not been observed by either photolysis or EB-induced reaction in a solution. The kinetic data revealed that the biphenyl salt 2-Ms exhibited 3.7 times greater kinetic constants for consumption than that of 1-Ms. The EB-induced reaction of benzene-substituted triphenylsulfonium salts, p-biphenyldiphenylsulfonium methanesulfonate (2p-Ms) and (4-phenylthiophenyl)diphenyl- sulfonium methanesulfonate (7) showed the consumption rates of 3.8 and 5.7 times greater than that of 1-Ms. The sulfonium salts with aromatic counter anions showed somewhat higher reactivity than those with aliphatic counter anions. Accordingly, it is concluded that the triphenylsulfonium salts having aryl groups, which exhibit lower ionization potential (Ip), in both cation and anion moieties should exhibit greater decomposition rates.
Matsuda, Makoto; Takeuchi, Suehiro; Tsukihashi, Yoshihiro; Horie, Katsuzo*; Ouchi, Isao*; Hanashima, Susumu; Abe, Shinichi; Ishizaki, Nobuhiro; Tayama, Hidekazu; Nakanoya, Takamitsu; et al.
Dai-18-Kai Tandemu Kasokuki Oyobi Sono Shuhen Gijutsu No Kenkyukai Hokokushu, p.11 - 14, 2005/11
no abstracts in English
Nakamura, Masahiko; Hanashima, Susumu; Nakanoya, Takamitsu; Yoshida, Tadashi*
Dai-18-Kai Tandemu Kasokuki Oyobi Sono Shuhen Gijutsu No Kenkyukai Hokokushu, p.84 - 87, 2005/11
no abstracts in English
Enomoto, Kazuyuki*; Maekawa, Yasunari; Katsumura, Yosuke*; Miyazaki, Toyoaki*; Yoshida, Masaru; Hamana, Hiroshi*; Narita, Tadashi*
Macromolecules, 38(23), p.9584 - 9593, 2005/11
Radiation-induced radical polyaddition of bis(-trifluoromethyl-,-difluorovinyl) terephthalate [CF=C(CF3)OCOCHCOOC(CF)=CF] (BFP) in the presence of an excess of cyclic and acyclic ethers in feed was examined at 0C using -rays irradiation. Irradiation of BFP with an 8-fold excess of 1,4-dioxane (DOX) and diethyl ether (EE) gave monomodal polymers consisting of the ernating unit of BFP and DOX moieties (poly(BFP--DOX), = 5.110) and of BFP and EE (poly(BFP--EE), =3.910), respectively. The irradiation of BFP with an 8-fold excess of tetrahydrofuran or tetrahydropyran provided only 1:2 addition products in high yields. Mono-functional 2-benzoxypentafluoropropene [CF=C(CF)OCOCH] (BPFP) as a model compound showed preferential formation of the 2:1 adduct to the 1:1 adduct with DOX and EE. The kinetic analysis of the model reactions revealed that the rate constants for the formation of the 2:1 adducts (k) of BPFP with DOX and EE were two orders of magnitude higher than those of the 1:1 adducts (k). Poly(BFP--DOX) showed higher radiation resistance than poly(BFP--EE) in solid states as well as in solution. It was concluded that radiation-induced step-growth polymerization under the stoichiometric imbalance of the two compounds requires a high k/k value as well as high radiation resistance for the formation of high molecular weight polymers.
Harada, Hideo; Yoshida, Tadashi*
Kaku Deta Nyusu (Internet), (81), p.39 - 47, 2005/00
Enomoto, Kazuyuki*; Narita, Tadashi*; Maekawa, Yasunari; Yoshida, Masaru; Hamana, Hiroshi*
Journal of Fluorine Chemistry, 125(7), p.1153 - 1158, 2004/07
Radical polyaddition of bis(-trifluoromethyl-,-difluorovinyl) terephthalate (BFP) with 1,4-dioxane (DOX) afforded higher molecular weight polymers under -rays compared to those yielded by benzoyl peroxide initiation. More detailed study on the radiation-induced polyaddition of BFP with DOX and optimization of the reaction conditions were carried out. It was necessary to irradiate with doses of 2000, 1500, and 750 kGy, to obtain quantitative conversion of BFP at the feed molar ratio DOX/BFP of 8.0, 16, and 32, respectively. Step-growth polymerization mechanism was suggested by the measurements of molecular weights of the polymers obtained with several irradiation doses. It was concluded that the molecular weight of the polymer could be controlled by the feed molar ratio of DOX/BFP and irradiation doses. The reaction between polymers might take place after the quantitative conversion of BFP. Radiation-induced radical polyaddition mechanism of BFP with DOX was proposed.
Enomoto, Kazuyuki*; Maekawa, Yasunari; Moon, S.; Shimoyama, Junji*; Goto, Kazuyuki*; Narita, Tadashi*; Yoshida, Masaru
Journal of Photopolymer Science and Technology, 17(1), p.41 - 44, 2004/06
The Electron beams (EB)-induced reactions of triphenylsulfonium methanesulfonate (1) in the crystalline state gave benzene-substituted product, biphenylsulfonium methanesulfonate (2), which has not been observed by either photolysis. In this paper, the EB-induced reactions of triphenylsulfonium salt derivatives, which possesses aromatic/aliphatic counter anions, have been examined. The anionic moiety of sulfonium salts has practically little effect on the formation of biphenyl salt 2 as well as the other products. The consumption rates of the sulfonium salts containing aromatic counter anions are somewhat smaller in a crystalline state and about two times larger than those of the salts with aliphatic counter anions. The greater decomposition rates of the sulfonium salts with aromatic counter anions than those of aliphatic counter anions in an amorphous state are elucidated by lower ionization potential of the salts with aromatic counter anions such as tosyl and naphthyl groups than those with aliphatic counter anions.