First direct mass measurements of nuclides around = 100 with a multireflection time-of-flight mass spectrograph

Ito, Yuta*; Schury, P.*; Wada, Michiharu*; Arai, Fumiya*; Haba, Hiromitsu*; Hirayama, Yoshikazu*; Ishizawa, Satoshi*; Kaji, Daiya*; Kimura, Sota*; Koura, Hiroyuki; et al.

Physical Review Letters, 120(15), p.152501_1 - 152501_6, 2018/04

https://doi.org/10.1103/PhysRevLett.120.152501

Masses of Es, Fm and the transfermium nuclei Md, and No, produced by hot- and cold-fusion reactions, in the vicinity of the deformed neutron shell closure, have been directly measured using a multi-reflection time-of-flight mass spectrograph. The masses of Es and Md were measured for the first time. Using the masses of Md as anchor points for decay chains, the masses of heavier nuclei, up to Bh and Mt, were determined. These new masses were compared with theoretical global mass models and demonstrated to be in good agreement with macroscopic-microscopic models in this region. The empirical shell gap parameter derived from three isotopic masses was updated with the new masses and corroborate the existence of the deformed neutron shell closure for Md and Lr.

A Multi-reflection time-of-flight mass spectrograph for short-lived and super-heavy nuclei

Schury, P. H.*; Wada, Michiharu*; Ito, Yuta*; Naimi, S.*; Sonoda, Tetsu*; Mita, Koki*; Takamine, Aiko*; Okada, Kunihiro*; Wollnik, H.*; Chon, S.*; et al.

Nuclear Instruments and Methods in Physics Research B, 317(Part B), p.537 - 543, 2013/12

https://doi.org/10.1016/j.nimb.2013.06.025

A multi-reflection time-of-flight (MRTOF) mass spectrograph has been implemented at RIKEN to provide high-precision mass measurements of very short-lived nuclei. Of particular interest are mass measurements of r-process nuclei and trans-uranium nuclei. In such nuclei, the MRTOF can perform on par with or better than traditional Penning trap systems. We demonstrate that the MRTOF-MS is capable of accurately attaining relative mass precision of m/m 10 and describe it's utility with heavy, short-lived nuclei.

Fabrication and tests of EF conductors for JT-60SA

Kizu, Kaname; Kashiwa, Yoshitoshi; Murakami, Haruyuki; Obana, Tetsuhiro*; Takahata, Kazuya*; Tsuchiya, Katsuhiko; Yoshida, Kiyoshi; Hamaguchi, Shinji*; Matsui, Kunihiro; Nakamura, Kazuya*; et al.

Fusion Engineering and Design, 86(6-8), p.1432 - 1435, 2011/10

https://doi.org/10.1016/j.fusengdes.2011.01.028

In JT-60SA, central solenoid (CS) and plasma equilibrium field (EF) coils are procured by Japan. EF coil conductors are NbTi cable-in-conduit (CIC) conductor. Delivered superconducting cables and jackets are fabricated into CIC conductors at the jacketing facility with the length of 680 m constructed in the Naka site of JAEA. The production of superconductors with 444 m in length for actual EF coils was started from March 2010. The measurements of superconducting performance like current sharing temperature (Tcs) were conducted prior to the mass production. The measured Tcs was agreed with the expectation values from strand values indicating that no degradation was happened by production process.

Neutron diffraction measurements of internal strain in NbSn cable-in-conduit conductors

Hemmi, Tsutomu; Harjo, S.; Ito, Takayoshi; Matsui, Kunihiro; Nunoya, Yoshihiko; Koizumi, Norikiyo; Takahashi, Yoshikazu; Nakajima, Hideo; Aizawa, Kazuya; Suzuki, Hiroshi; et al.

IEEE Transactions on Applied Superconductivity, 21(3), p.2028 - 2031, 2011/06

https://doi.org/10.1109/TASC.2010.2089770

Residual strain in conductors is caused by the difference in the coefficient of expansion between NbSn strands and the jacket over a temperature range of 5 - 923 K. The superconducting properties of strands vary significantly, depending on the strain. It is important to clarify the residual strain as part of the evaluation of superconducting performance. However, the residual strain of strands in the conductor has not been measured so far because of their complicated configuration and their location in a jacket. The engineering materials diffractometer "Takumi" in J-PARC can measure residual strain with a relative accuracy of around 0.02%, using neutron diffraction. In this study, the Takumi was applied to the measurement of residual strain in strands for the ITER TF conductor. Results indicate that the residual strain of strands in the conductor can be determined, thereby clarifying the mechanism of residual strain and its relationship to superconducting performance.

Technology development for the manufacture of NbSn conductors for ITER Toroidal Field coils

Takahashi, Yoshikazu; Isono, Takaaki; Hamada, Kazuya; Nunoya, Yoshihiko; Nabara, Yoshihiro; Matsui, Kunihiro; Hemmi, Tsutomu; Kawano, Katsumi; Koizumi, Norikiyo; Oshikiri, Masayuki; et al.

Proceedings of 23rd IAEA Fusion Energy Conference (FEC 2010) (CD-ROM), 8 Pages, 2011/03

http://www-naweb.iaea.org/napc/physics/FEC/FEC2010/html/node89.htm#21018

Japan Atomic Energy Agency is procuring the NbSn superconductors for Toroidal Field (TF) coils under the ITER project. Because manufacturing amount of NbSn strands is quite large compared with the past experience and required superconducting performance is higher than that of the model coils which have been fabricated and tested in the ITER-EDA, quality control technique is very important for the manufacture of the strands. Sophisticated control technique is also required for the jacketing, in order to fabricate the conductors with the precise outer diameter and without leakage at welding part. Cu dummy conductor with full length (760 m) has been fabricated successfully and all jacketing technology was confirmed through this fabrication. The fabrication of the NbSn conductor for TF coils will start in March 2010.

High-pressure synthesis and physical properties of new iron (nickel)-based superconductors

Shirage, P. M.*; Miyazawa, Kiichi*; Ishikado, Motoyuki; Kiho, Kunihiro*; Lee, C.-H.*; Takeshita, Nao*; Matsuhata, Hirofumi*; Kumai, Reiji*; Tomioka, Yasuhide*; Ito, Toshimitsu*; et al.

Physica C, 469(9-12), p.355 - 369, 2009/06

https://doi.org/10.1016/j.physc.2009.03.027

We have utilized a high-pressure (HP) technique to synthesize a series of newly-discovered iron (nickel)-based superconductors. The effect of (O)-deficiency, variation of ions, and the external pressure on are examined. All the experimental data indicate strong correlation between the crystal structure and the superconductivity of the oxypnictide superconductors. Upper critical field measurement on single crystalline sample of PrFeAsO shows the superconducting anisotropy of 5, which is smaller than cuprates. We also demonstrate that HP technique is applicable for the so-called "122" systems.

The Recovery from water leakage accident in JMTR

Ito, Haruhiko; Homma, Kenzo; Itabashi, Yukio; Tabata, Toshio; Akashi, Kazutomo; Inaba, Yukio; Kumahara, Hajime; Takahashi, Kunihiro; Kitajima, Toshio; Yokouchi, Iichiro

JAERI-Review 2003-024, 76 Pages, 2003/10

JAERI-Review-2003-024.pdf:8.35MB

no abstracts in English

Improvement on core assembly irradiation bowing analysis method; Irradiation bowing analysis of JOYO inner reflector

Kikuchi, Shin; ; Ito, Kunihiro*

JNC TN9400 99-084, 92 Pages, 1999/12

JNC-TN9400-99-084.pdf:4.46MB

It is important to understand the deformation behaviors of core assembly in the aspect of the assembly life and the increase of removal load of assembly. Therefore, deformation behaviors of core assembly code: "BEACON" was being developed in order to evaluate these behaviors. However, there is a problem that the irradiation bowing modes and displacements of the JOYO assemblies obtained by the analysis were so different from the PIE data. In this study, the analysis condition, the application of analysis code and model were investigated through analysis on the JOYO Inner Reflector assembly based on PIE data.

Test results of the SMES model coil; Pulse performance

Hamajima, Takataro*; Shimada, Mamoru*; Ono, Michitaka*; Takigami, Hiroyuki*; Hanai, Satoshi*; Wachi, Yoshihiro*; Takahashi, Yoshikazu; Matsui, Kunihiro; Ito, Toshinobu*; Isono, Takaaki; et al.

Teion Kogaku, 33(7), p.492 - 499, 1998/00

https://doi.org/10.2221/jcsj.33.492

no abstracts in English

An evaluation of core characteristics for TRU transmutation (III)

*; Mizuno, Mineo*; *; Ito, Kunihiro*; *; *

PNC TJ9678 95-003, 195 Pages, 1995/03

PNC-TJ9678-95-003.pdf:4.35MB

In preceding years, as the method of TRU transmutation (TRU means Minor Actinide such as Np, Am and Cm in this report) in FBR, we have evaluated core characteristics and TRU transmuting characteristics for two TRU loading methods : homogeneous TRU-loading method where the TRU fuel is dispersed uniformly throughout the core; and heterogeneous TRU-loading method where a few number of subassemblies with concentrated TRU fuel (target S/As) are loaded in the core. Also, as the research on the TRU transmutation by FBR plant, the survey have been conducted for the effect upon the core characteristics and the TRU transmuting characteristics affected by RE(Rare Earth) which is entrapped when TRU is separated from the high level waste. At the same time, the effect have been surveyed in the case where the TRU recycle was executed in FBR. In this fiscal year, the investigation have been conducted for a core concept in which TRU are loaded separately between the group of Np and the group of Am + Cm + RE , according to the results of advancement of nuclear fuel reprocessing technology. The core concepts with excellent TRU transmuting characteristic have been investigated for the separate loading method of Np and Am + Cm by adding only Np in the core region and adding Am, Cm and RE in the target assemblies located at radial blanket location of the core periphery. As the result of investigation, it has been found that the total amount of TRU up to around 20 % is possible in the case of loading 72 target assemblies composed of 271 pins with the pin diameter almost equal to that of the core fuel, and the TRU amount transmuted per cycle becomes 580 kg which is 3 4 times higher than the conventional TRU loading methods such as homogeneous loading and heterogeneous loading. The main core characteristics of this core concept are as follows, and the core design is feasible, : ...