Progress status and future issues of development of analysis and estimation technology for fuel debris characterization, 5; Progress status of development of Non-Destructive assay technologies for sorting and segregation of fuel debris and others

Kamada, Masaki*; Yoshida, Takuma*; Sugita, Tsukasa*; Okumura, Keisuke

Nihon Genshiryoku Gakkai-Shi ATOMO, 66(2), p.83 - 86, 2024/02

https://doi.org/10.3327/jaesjb.66.2_83

no abstracts in English

Photoneutron cross sections for Sn and the -ray strength function method

Utsunomiya, Hiroaki*; Goriely, S.*; Kamata, Masaki*; Akimune, Hidetoshi*; Kondo, Takeo*; Ito, Osamu*; Iwamoto, Chihiro*; Yamagata, Tamio*; Toyokawa, Hiroyuki*; Lui, Y.-W.*; et al.

Physical Review C, 84(5), p.055805_1 - 055805_6, 2011/11

https://doi.org/10.1103/PhysRevC.84.055805

Photoneutron cross sections were measured for Sn, Sn, Sn, Sn, and Sn near neutron threshold with quasi-monochromatic laser-Compton scattering -rays. A systematic analysis of the present photoneutron data and existing neutron-capture data is made using the -ray strength function on the basis of the HFB+QRPA model of E1 strength supplemented with a pygmy dipole resonance, which was deduced from a previous study on Sn and Sn. Radiative neutron capture cross sections for two radioactive nuclei, Sn and Sn, are deduced through the -ray strength function method.

Application of the SF method to palladium

Utsunomiya, Hiroaki*; Goriely, S.*; Arteaga, D. P.*; Daoutidis, I.*; Akimune, Hidetoshi*; Yamagata, Tamio*; Kondo, Takeo*; Iwamoto, Chihiro*; Kamata, Masaki*; Ito, Osamu*; et al.

AIP Conference Proceedings 1377, p.450 - 452, 2011/10

https://doi.org/10.1063/1.3628442

-ray strength function method and its application to Pd

Utsunomiya, Hiroaki*; Goriely, S.*; Akimune, Hidetoshi*; Harada, Hideo; Kitatani, Fumito; Goko, Shinji*; Toyokawa, Hiroyuki*; Yamada, Kawakatsu*; Kondo, Takeo*; Ito, Osamu*; et al.

Physical Review C, 82(6), p.064610_1 - 064610_5, 2010/12

https://doi.org/10.1103/PhysRevC.82.064610

The -ray strength function method (SF method) is devised to indirectly determine radiative neutron capture cross sections for radioactive nuclei. This method is applied here to the Pd case. Photoneutron cross sections were measured for Pd near neutron threshold with quasi-monochromatic laser-Compton-scattering -ray beams. These photoneutron cross sections as well as the reverse radiative neutron capture cross sections for Pd are used to provide constraints on the Pd(n,) Pd cross section.

Photoneutron cross sections for Zr; A Systematic experimental study of photoneutron and radiative neutron capture cross sections for zirconium isotopes

Utsunomiya, Hiroaki*; Goriely, S.*; Akimune, Hidetoshi*; Harada, Hideo; Kitatani, Fumito; Goko, Shinji; Toyokawa, Hiroyuki*; Yamada, Kawakatsu*; Kondo, Takeo*; Ito, Osamu*; et al.

Physical Review C, 81(3), p.035801_1 - 035801_5, 2010/03

https://doi.org/10.1103/PhysRevC.81.035801

This manuscript presents photoneutron cross sections for Zr. Combining the present data with the previously published Zr data, we investigated the -ray strength function for zirconium isotopes systematically. We present a unified picture of the -ray strength function that consists of the HFB + QRPA model of E1 strength accompanied by an extra M1 strength attributable to giant M1 resonance. It is shown that the -ray strength function reproduces both (g,n) and (n,g) cross sections for Zr isotopes consistently.

Energy spectra of bremsstrahlung X-rays emitted from an FRP insulator

Tanaka, Yutaka; Ikeda, Yoshitaka; Hanada, Masaya; Kobayashi, Kaoru; Kamada, Masaki; Kisaki, Masashi; Akino, Noboru; Yamano, Yasushi*; Kobayashi, Shinichi*; Grisham, L. R.*

IEEE Transactions on Plasma Science, 37(8), p.1495 - 1498, 2009/08

https://doi.org/10.1109/TPS.2009.2020402

Voltage holding capability of the JT-60 negative ion source is limited by surface flashover on the FRP insulator. To improve the voltage holding capability of the ion source, the understanding of the surface flashover is required. In this study, electron energy is estimated by measuring the bremsstrahlung X-ray emitted from an FRP insulator. Energy spectra of X-ray were measured for 3 different positions and compared with those of the vacuum gap between electrodes. Near the anode, X-ray spectrum was dominated by the monoenergetic electron. Near the cathode, spectrum peak shifted to low energy compared with that near the anode. This result showed that a large amount of low energy electrons was generated on the surface of the FRP insulator near the cathode.

Compensation of beamlet repulsion in a large negative ion source with a multi aperture accelerator

Kashiwagi, Mieko; Inoue, Takashi; Grisham, L. R.*; Hanada, Masaya; Kamada, Masaki; Taniguchi, Masaki; Umeda, Naotaka; Watanabe, Kazuhiro

AIP Conference Proceedings 1097, p.421 - 430, 2009/03

https://doi.org/10.1063/1.3112541

One of the issues in long pulse operation of large negative ion source with multiaperture accelerator is an excess heat loads on to grids by the beamlet deflection due to their space charge repulsion. To compensate this beamlet deflection, the beamlet steering technique by aperture offset was examined in a three dimensional beam analyses simulating D negative ion source of JT-60U. The result shows that proper aperture offsets of 1.0 mm were enough to compensate each beamlet deflection. When the magnetic field for suppression of co-extracted electrons was applied, necessary aperture offset of 0.5 mm was necessary for 500 keV D ion beam in JT-60U in addition to the offset for compensation of space charge repulsion. The numerical analyses showed good agreement with the former experimental results and design study.

Recent R&D activities of negative-ion-based ion source for JT-60SA

Ikeda, Yoshitaka; Hanada, Masaya; Kamada, Masaki; Kobayashi, Kaoru; Umeda, Naotaka; Akino, Noboru; Ebisawa, Noboru; Inoue, Takashi; Honda, Atsushi; Kawai, Mikito; et al.

IEEE Transactions on Plasma Science, 36(4), p.1519 - 1529, 2008/08

https://doi.org/10.1109/TPS.2008.927382

The JT-60SA N-NBI system is required to inject 10 MW for 100 s at 500 keV. Three key issues should be solved for the JT-60SA N-NBI ion source. One is to improve the voltage holding capability. Recent R&D tests suggested that the accelerator with a large area of grids may need a high margin in the design of electric field and a long time for conditioning. The second issue is to reduce the grid power loading. It was found that some beamlets were strongly deflected due to beamlet-beamlet interaction and strike on the grounded grid. The grids are to be designed by taking account of beamlet-beamlet interaction in three-dimensional simulation. Third is to maintain the D- production for 100 s. A simple cooling structure is proposed for the active cooled plasma grid, where a key is the temperature gradient on the plasma grid for uniform D- production. The modified N-NBI ion source will start on JT-60SA in 2015.

Breakdown location without beam acceleration in the JT-60U negative ion source

Kobayashi, Kaoru; Hanada, Masaya; Kamada, Masaki; Akino, Noboru; Sasaki, Shunichi; Ikeda, Yoshitaka

JAEA-Technology 2008-042, 25 Pages, 2008/06

JAEA-Technology-2008-042.pdf:4.16MB

Breakdown locations of a JT-60U negative ion source were investigated to improve the voltage holding capability. The accelerator is characterized by three acceleration stages with large grids 0.45 m 1.1 m and large FRP insulators 1.8 m in inner diameter. High voltages were applied to each acceleration stage independently. Voltage holding capabilities of each stage were almost the same, 120-130 kV, which was lower than the design acceleration voltage of 167 kV. Then, in order to identify whether the breakdowns occur in the gaps between grids or on the surface of the FRP insulators, high voltages were also applied to the accelerator with the grids and their support flanges removed. The voltage holding capabilities of three FRP insulators rapidly achieved 167 kV. These results indicate that the breakdowns mainly occur in the gaps between the acceleration grids and/or their support flanges.

Long pulse production of high current D ion beams in the JT-60 negative ion source

Hanada, Masaya; Kamada, Masaki; Akino, Noboru; Ebisawa, Noboru; Honda, Atsushi; Kawai, Mikito; Kazawa, Minoru; Kikuchi, Katsumi; Komata, Masao; Mogaki, Kazuhiko; et al.

Review of Scientific Instruments, 79(2), p.02A519_1 - 02A519_4, 2008/02

https://doi.org/10.1063/1.2821508

A long pulse production of high-current, high-energy D ion beams was studied in the JT-60U negative ion source that was designed to produce 22 A, 500 keV D ion beams. Prior to the long pulse production, the short pulse beams were produced to examine operational ranges for a stable voltage holding capability and an allowable grid power loading. From a correlation between the voltage holding capability and a light intensity of cathodoluminescence from the insulator made of Fiber Reinforced Plastic insulator, the voltage holding was found to be stable at 340 kV where the light was sufficiently suppressed. The grid power loading for the long pulse operation was also decreased to the allowable level of 1 MW without a significant reduction of the beam power by tuning the extraction voltage (Vext) and the arc power (Parc). These allow the production of 30 A D ion beams at 340 keV from two ion sources at Vacc = 340 kV. The pulse length was extended step by step, and finally reached up to 21 s, where the beam pulse length was limited by the surface temperature of the beam scraper without water cooling. The D ion beams were neutralized to via a gas cell, resulting in a long pulse injection of 3.2 MW D beams for 21 s. This is the first long injection of 20 s in a power range of 3 MW.