Compliance measures at the Radioactive Waste Treatment Facilities at the Nuclear Science Research Institute; Aseismic reinforcement of the Radioactive Waste Treatment Facility No. 3, Waste Size Reduction and Storage Facility, and Waste Volume Reduction Facility

Iketani, Shotaro; Suzuki, Takeshi; Yokobori, Tomohiko; Sugawara, Satoshi; Yokota, Akira; Kikuchi, Genta; Muraguchi, Yoshinori; Kitahara, Masaru; Seya, Manato; Kurosawa, Tsuyoshi; et al.

JAEA-Technology 2025-001, 169 Pages, 2025/08

JAEA-Technology-2025-001.pdf:14.22MB

The radioactive waste treatment facilities at the Nuclear Science Research Institute includes the Radioactive Waste Treatment Facility No. 3, Waste Size Reduction and Storage Facility, and Waste Volume Reduction Facility. These three facilities come under the purview of the Act on the Regulation of Nuclear Source Material, Nuclear Fuel Material and Reactors, and are included under Class C of the act based on the seismic requirements specified in the Act. We assessed the seismic capacity of these three radioactive waste treatment facilities based on the current Building Standards Act, to verify whether they comply with the new regulatory requirements enforced by the Nuclear Regulation Authority (NRA) in the aftermath of the 2011 nuclear accident at the Fukushima Daiichi Nuclear Power Station operated by the Tokyo Electric Power Company. We found that the allowable stress of a few structural members used in the construction of the facilities did not meet the regulatory requirements. After studying the approval granted by the NRA for the construction plans, including the design and construction methods (design and construction plans) of the three facilities on March 5, 2021, we made aseismic reinforcement at these facilities between 2021 and 2022. This report presents an overview of the seismic design of these facilities and an outline of the aseismic reinforcement conducted, management system existing, safety measures adopted, and the preoperational inspections conducted at these facilities.

New precise measurement of muonium hyperfine structure interval at J-PARC

Ueno, Yasuhiro*; Aoki, Masaharu*; Fukao, Yoshinori*; Higashi, Yoshitaka*; Higuchi, Takashi*; Iinuma, Hiromi*; Ikedo, Yutaka*; Ishida, Katsuhiko*; Ito, Takashi; Iwasaki, Masahiko*; et al.

Hyperfine Interactions, 238(1), p.14_1 - 14_6, 2017/11

https://doi.org/10.1007/s10751-016-1381-7

Safety managements of the linear IFMIF/EVEDA prototype accelerator

Takahashi, Hiroki; Maebara, Sunao; Kojima, Toshiyuki; Narita, Takahiro; Tsutsumi, Kazuyoshi; Sakaki, Hironao; Suzuki, Hiromitsu; Sugimoto, Masayoshi

Fusion Engineering and Design, 89(9-10), p.2066 - 2070, 2014/10

https://doi.org/10.1016/j.fusengdes.2014.02.051

Excitation functions for production of Rf isotopes in the Cm + O reaction

Murakami, Masashi*; Goto, Shinichi*; Murayama, Hirofumi*; Kojima, Takayuki*; Kudo, Hisaaki*; Kaji, Daiya*; Morimoto, Koji*; Haba, Hiromitsu*; Kudo, Yuki*; Sumita, Takayuki*; et al.

Physical Review C, 88(2), p.024618_1 - 024618_8, 2013/08

https://doi.org/10.1103/PhysRevC.88.024618

Production cross sections of Rf isotopes in the Cm + O reaction were measured at the beam energy range of 88.2 to 101.3 MeV by use of a gas-filled recoil ion separator. The excitation functions of Rf, Rf, and Rf were obtained together with those of spontaneously fissioning nuclides which have few-second half-lives and have been assigned to Rf and a longer-lived state of Rf. The excitation function of few-second spontaneously fissioning nuclide exhibited the maximum cross section at the O beam energy of 94.8 MeV. The shape of the excitation function was almost the same as that of Rf, whereas it was quite different from those of Rf and Rf. A few-second spontaneously fissioning nuclide previously reported as Rf and Rf observed inCm + O reaction was identified as Rf.

Neutron one-quasiparticle states in Fm populated via the decay of No

Asai, Masato; Tsukada, Kazuaki; Haba, Hiromitsu*; Ishii, Yasuo; Ichikawa, Takatoshi*; Toyoshima, Atsushi; Ishii, Tetsuro; Nagame, Yuichiro; Nishinaka, Ichiro; Kojima, Yasuaki*; et al.

Physical Review C, 83(1), p.014315_1 - 014315_12, 2011/01

https://doi.org/10.1103/PhysRevC.83.014315

Excited states in Fm populated via the decay of No are studied in detail through - coincidence and fine structure measurements. Spin-parities and neutron configurations of the excited states in Fm as well as the ground state of No are definitely identified on the basis of deduced internal conversion coefficients, lifetimes of transitions, rotational-band energies built on one-quasiparticle states, and hindrance factors of transitions. It is found that the excitation energy of the 1/2[620] state in =151 isotones increases with the atomic number, especially at 100, while that of the 1/2[631] state decreases at =100. Energy systematics of the one-quasiparticle states in the =151 isotones are discussed in terms of the evolution of nuclear deformation involving the hexadecapole and hexacontatetrapole deformations.

Transient absorption of a cation radical of pyrene induced by heavy ion beam pulses

Kondo, Takafumi*; Yang, J.*; Kan, Koichi*; Yoshida, Yoichi*; Shibata, Hiromi*; Taguchi, Mitsumasa; Kojima, Takuji

JAEA-Review 2007-060, JAEA Takasaki Annual Report 2006, P. 160, 2008/03

no abstracts in English

decay of Cm and the new isotope Cm

Asai, Masato; Tsukada, Kazuaki; Ichikawa, Shinichi; Sakama, Minoru*; Haba, Hiromitsu*; Nishinaka, Ichiro; Nagame, Yuichiro; Goto, Shinichi*; Kojima, Yasuaki*; Oura, Yasuji*; et al.

Physical Review C, 73(6), p.067301_1 - 067301_4, 2006/06

https://doi.org/10.1103/PhysRevC.73.067301

no abstracts in English

-decay half-lives of new neutron-rich rare-earth isotopes Pm, Sm, and Gd

Ichikawa, Shinichi; Asai, Masato; Tsukada, Kazuaki; Haba, Hiromitsu*; Nagame, Yuichiro; Shibata, Michihiro*; Sakama, Minoru*; Kojima, Yasuaki*

Physical Review C, 71(6), p.067302_1 - 067302_4, 2005/06

https://doi.org/10.1103/PhysRevC.71.067302

The new neutron-rich raer-earth isotopes Pm, Sm, and Gd produced in the proton-induced fission of 238U were identified using the JAERI on-line isotope separator (JAERI-ISOL) coupled to a gas-jet transport sysetm. The half-lives of Pm, Sm, and Gd were determined to be 1.50.2s, 2.40.5s, and 4.81.0s, respectively. The partial decay scheme of Gd wes constructed for - coincidence data. The improved half-life values of 25.62.2s wes obtained for the previously identified isotope Tb. The half-lives measured in the present study are in good agreement with the theoretical predictions calculated by the second generation of the gross theory with the atomic masses evaluated by the Audei and Wapstra.

EC and decays of Am

Asai, Masato; Sakama, Minoru*; Tsukada, Kazuaki; Ichikawa, Shinichi; Haba, Hiromitsu*; Nishinaka, Ichiro; Nagame, Yuichiro; Goto, Shinichi*; Kojima, Yasuaki*; Oura, Yasuji*; et al.

European Physical Journal A, 22(3), p.411 - 416, 2004/12

https://doi.org/10.1140/epja/i2004-10044-6

EC and decays of Am have been studied by means of -ray spectroscopy. Excited states in Pu have been established for the first time, and tentative spin-parity and Nilsson assignments were given to these levels. The ground state of Am was evaluated to be the state from the experimental results. It was found that the state in Np is located at 15~keV, which allowed us to determine the value of Am as 6569~keV, in combination with the measured -particle energy.

Absorbed dose rate distribution in 300 keV electron beam irradiation field for waste-gas purification

Hakoda, Teruyuki; Sunaga, Hiromi; Takizawa, Haruki; Hirota, Koichi; Kojima, Takuji

Radioisotopes, 53(2), p.59 - 69, 2004/02

https://doi.org/10.3769/radioisotopes.53.59

no abstracts in English