In-situ dismantling of the liquid waste storage tank LV-1 in the JRTF; The Dismantling work

Yokozuka, Yuta; Sunaoshi, Mizuho*; Sakai, Tatsuya; Fujikura, Toshiki; Handa, Yuichi; Muraguchi, Yoshinori; Mimura, Ryuji; Terunuma, Akihiro

JAEA-Technology 2021-037, 44 Pages, 2022/03

JAEA-Technology-2021-037.pdf:10.84MB

JAEA has dismantled equipment and instrument in the JAERI's Reprocessing Test Facility (JRTF) since 1996 as a part of its decommissioning. Starting in JFY 2007, in the annex building B which stored liquid waste generated in wet reprocessing tests, the liquid waste storage tank LV-1 installed in the LV-1 room of the first basement was dismantled with the in-situ dismantling method. The dismantling work is described in this report. Data on manpower, radiation control, and waste in the preparation work were collected, and its work efficiency was analyzed.

High peak-current lightning discharges associated with downward terrestrial gamma-ray flashes

Wada, Yuki*; Enoto, Teruaki*; Nakamura, Yoshitaka*; Morimoto, Takeshi*; Sato, Mitsuteru*; Ushio, Tomoo*; Nakazawa, Kazuhiro*; Yuasa, Takayuki*; Yonetoku, Daisuke*; Sawano, Tatsuya*; et al.

Journal of Geophysical Research; Atmospheres, 125(4), p.e2019JD031730_1 - e2019JD031730_11, 2020/02

https://doi.org/10.1029/2019JD031730

Materials and Life Science Experimental Facility at the Japan Proton Accelerator Research Complex, 3; Neutron devices and computational and sample environments

Sakasai, Kaoru; Sato, Setsuo*; Seya, Tomohiro*; Nakamura, Tatsuya; To, Kentaro; Yamagishi, Hideshi*; Soyama, Kazuhiko; Yamazaki, Dai; Maruyama, Ryuji; Oku, Takayuki; et al.

Quantum Beam Science (Internet), 1(2), p.10_1 - 10_35, 2017/09

https://doi.org/10.3390/qubs1020010

Neutron devices such as neutron detectors, optical devices including supermirror devices and He neutron spin filters, and choppers are successfully developed and installed at the Materials Life Science Facility (MLF) of the Japan Proton Accelerator Research Complex (J-PARC), Tokai, Japan. Four software components of MLF computational environment, instrument control, data acquisition, data analysis, and a database, have been developed and equipped at MLF. MLF also provides a wide variety of sample environment options including high and low temperatures, high magnetic fields, and high pressures. This paper describes the current status of neutron devices, computational and sample environments at MLF.

Quantitative measurements of element distributions using the neutron-transmission resonance-absorption method

Harada, Masahide; Parker, J. D.*; Sawano, Tatsuya*; Kubo, Hidetoshi*; Tanimori, Toru*; Shinohara, Takenao; Maekawa, Fujio; Sakai, Kenji

Physics Procedia, 43, p.314 - 322, 2013/00

https://doi.org/10.1016/j.phpro.2013.03.037

The purposes of this study are to perform Neutron Resonance Absorption NRA test experiments using the Micro Pixel Chamber, and to confirm its quantitativity. The detector was located at 14.5 m from the moderator in the experimental room of NOBORU. The samples, consisting of thin Tantalum (Ta) foils, with thicknesses of 5, 10, 20 and 100 m, were placed individually at 15 cm upstream from the detector. In the experiment, the transmission spectra with the Ta samples and no sample were obtained. Background components were not so small in these measurements. From the neutron transport simulation, it was surmised that the origin of this background was due to scattering of neutrons in the experimental room. Therefore, the assumed background components were subtracted from the measurement data. Finally, it was found that the difference between the measurement data and the nuclear data was within about 7%.

Azimuthal correlations of electrons from heavy-flavor decay with hadrons in and Au+Au collisions at = 200 GeV

Adare, A.*; Afanasiev, S.*; Aidala, C.*; Ajitanand, N. N.*; Akiba, Yasuyuki*; Al-Bataineh, H.*; Alexander, J.*; Aoki, Kazuya*; Aphecetche, L.*; Aramaki, Y.*; et al.

Physical Review C, 83(4), p.044912_1 - 044912_16, 2011/04

https://doi.org/10.1103/PhysRevC.83.044912

Measurements of electrons from the decay of open-heavy-flavor mesons have shown that the yields are suppressed in Au+Au collisions compared to expectations from binary-scaled collisions. Here we extend these studies to two particle correlations where one particle is an electron from the decay of a heavy flavor meson and the other is a charged hadron from either the decay of the heavy meson or from jet fragmentation. These measurements provide more detailed information about the interaction between heavy quarks and the quark-gluon matter. We find the away-side-jet shape and yield to be modified in Au+Au collisions compared to collisions.

Effect of experimental conditions on gas core length and downward velocity of free surface vortex in cylindrical vessel

Monji, Hideaki*; Shinozaki, Tatsuya*; Kamide, Hideki; Sakai, Takaaki

Journal of Engineering for Gas Turbines and Power, 132(1), p.012901_1 - 012901_8, 2010/01

https://doi.org/10.1115/1.3078704

This paper deals with characteristics of surface vortex in a cylindrical vessel. One of the characteristics is a gas core length which is important to estimate the onset condition of the gas entrainment but influenced easily by the experimental condition. In the experiment using water, the effects of the water temperature, water level and the surface tension on the gas core length were investigated. The onset condition of the gas entrainment is sometimes estimated by using the Burgers vortex model but the real flow in the vessel is different from the model. The velocity fields were measured by PIV and the velocity gradient of the downward flow was discussed. The proper flow conditions for the Burgers vortex model are a high water level and a high flow rate.

Ga NQR relaxation rates in superconductor PuRhGa

Sakai, Hironori; Kambe, Shinsaku; Tokunaga, Yo; Fujimoto, Tatsuya; Walstedt, R. E.*; Yasuoka, Hiroshi; Aoki, Dai*; Homma, Yoshiya*; Yamamoto, Etsuji; Nakamura, Akio; et al.

Journal of Physics and Chemistry of Solids, 68(11), p.2103 - 2106, 2007/11

https://doi.org/10.1016/j.jpcs.2007.08.039

A lot of attention is currently focused on Pu-based superconductors. These systems have relatively high superconducting (SC) transition temperatures, 18 K for PuCoGa and 9 K for PuRhGa. Both compounds crystallize in the tetragonal HoCoGa (115) structure, which is well known for the heavy-fermion SC systems CeIn (=Co, Rh, Ir)with 2 K at most. Recently, NMR and NQR experiments have been reported for PuCoGa by Curro et al. and for PuRhGa by our group. In both cases, measurements of using NQR have revealed that the Pu115 superconductors show unconventional superconductivity with an anisotropic gap. Now we have measured the more detailed data of for NQR lines in PuRhGa, especially focusing on the low-lying magnetic excitation in the normal state. From the viewpoint of spin-fluctuations, we will discuss the difference between PuRhGa and PuCoGa and between superconducting Pu115 and non-superconducting An115 series.

NMR studies of actinide dioxides

Tokunaga, Yo; Sakai, Hironori; Fujimoto, Tatsuya; Kambe, Shinsaku; Walstedt, R. E.*; Ikushima, Kenji*; Yasuoka, Hiroshi; Aoki, Dai*; Homma, Yoshiya*; Haga, Yoshinori; et al.

Journal of Alloys and Compounds, 444-445, p.241 - 245, 2007/10

https://doi.org/10.1016/j.jallcom.2007.03.082

In this paper, we present our recent NMR works on Neptunium and Plutonium compounds. In order to elucidate the nature of the exotic multipolar ordered phase of NpO, we have initiated the first NMR measurements on this system. We have shown that direct observation of multipole order parameters is possible by means of NMR. Our NMR results provide further insight into the microscopic nature of multipole phase transitions in f-electron systems. We have also performed Ga NMR/NQR studies on a single crystal of PuRhGa. From the temperature dependence of the spin-lattice relaxation rate (), we have found that PuRhGa is an unconventional superconductor having an anisotropic superconducting (SC) gap 2=5. Furthermore, we have confirmed the Knight shift to be decreased below . This gives strong evidence for spin singlet SC pairing.

NMR study of the semimetallic compound UCoGa

Kambe, Shinsaku; Sakai, Hironori; Kato, Harukazu*; Tokunaga, Yo; Fujimoto, Tatsuya*; Walstedt, R. E.*; Ikeda, Shugo; Maehira, Takahiro*; Haga, Yoshinori; Onuki, Yoshichika

Physical Review B, 76(2), p.024411_1 - 024411_6, 2007/07

https://doi.org/10.1103/PhysRevB.76.024411

We report NMR studies on a single crystal of UCoGa, which has the same tetragonal HoCoGa (115) structure as the-wave high- superconductor PuCoGa. The spin-lattice relaxation rate () in UCoGa issmall comparing with those of other actinide 115 compounds. This fact is consistent with a semi-metallic nature of UCoGa suggested by de Haas-van Alphen effect measurements and band calculations. From comparison of at crystallografically different Ga and Co sites and the static susceptibility, an existence of two bands with rather different characters is revealed.

Favorable magnetic fluctuation anisotropy for unconventional superconductivity in -electron systems

Kambe, Shinsaku; Sakai, Hironori; Tokunaga, Yo; Fujimoto, Tatsuya*; Walstedt, R. E.*; Ikeda, Shugo; Aoki, Dai*; Homma, Yoshiya*; Haga, Yoshinori; Shiokawa, Yoshinobu*; et al.

Physical Review B, 75(14), p.140509_1 - 140509_4, 2007/04

https://doi.org/10.1103/PhysRevB.75.140509

We report spin-lattice relaxation time measurements in isostructural (HoCoGa type) actinide compounds withdifferent ground states (paramagnet, antiferromagnet and superconductor) using single-crystal samples. The anisotropy oflocal magnetic fluctuation due to coupling on the actinide (magnetic) site is evaluated. In the superconductor PuRhGa, the type magnetic anisotropy is strong compared with non-superconducting compounds. Favorable magnetic anisotropy for -wave superconductivity in -electron systems is discussed.