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Journal Articles

Simultaneous determination of zircon crystallisation age and temperature; Common thermal evolution of mafic magmatic enclaves and host granites in the Kurobegawa granite, central Japan

Yuguchi, Takashi*; Yamazaki, Hayato*; Ishibashi, Kozue*; Sakata, Shuhei*; Yokoyama, Tatsunori; Suzuki, Satoshi*; Ogita, Yasuhiro; Sando, Kazusa*; Imura, Takumi*; Ono, Takeshi*

Journal of Asian Earth Sciences, 226, p.105075_1 - 105075_9, 2022/04

 Times Cited Count:0 Percentile:0.01(Geosciences, Multidisciplinary)

Simultaneous determination of the U-Pb age of zircon and concentration of titanium in a single analysis spot, using inductively coupled plasma mass spectrometry with laser ablation sample introduction, produces paired age and temperature data of zircon crystallisation, potentially revealing time-temperature ($$t-T$$) histories for evolved magma. The Kurobegawa granite, central Japan, contains abundant mafic magmatic enclaves (MMEs). We applied this method to evaluate MMEs and their host (enclosing) granites. Cooling behaviour common to both MMEs and host rocks was found between 1.5 and 0.5 Ma. Rapid cooling from the zircon crystallisation temperature to the closure temperature of biotite K-Ar system was within $$sim$$1 million year. Combining the obtained $$t-T$$ paths of MMEs and host rocks with petrological information can provide insights into magma chamber processes. This suggests that MME flotation, migration, and spread through the magma chamber ceased at 1.5-0.5 Ma, indicating the emplacement age of the Kurobegawa granitic pluton, as no large-scale reheating episodes have occurred since then.

Journal Articles

Present status and practical issues on dosimetry for the lens of the eye at JAEA MOX Fuel Facilities

Tsujimura, Norio; Yamazaki, Takumi; Takada, Chie

Journal of Nuclear Science and Technology, 58(1), p.40 - 44, 2021/01

 Times Cited Count:2 Percentile:23.17(Nuclear Science & Technology)

Journal Articles

Lens dosimetry study in $$^{90}$$Sr+$$^{90}$$Y beta field; Full-face mask respirator shielding and dosemeter positioning

Tsujimura, Norio; Hoshi, Katsuya; Yamazaki, Takumi; Momose, Takumaro; Aoki, Katsunori; Yoshitomi, Hiroshi; Tanimura, Yoshihiko; Yokoyama, Sumi*

KEK Proceedings 2020-5, p.21 - 28, 2020/11

Journal Articles

Present status and issues of dosimetry for the lens of the eye at the MOX-fuel plant

Yamazaki, Takumi; Takada, Chie; Tsujimura, Norio; Okada, Kazuhiko

Hoken Butsuri, 52(3), p.167 - 170, 2017/09

At the JAEA MOX Fuel Facilities, a worker engaged in glove box operations uses two personal dosemeters, one worn on the trunk under a protective apron and the other at the collar over the apron. The recorded lens of the eye dose is based on the photon dose measured by the collar dosemeter plus the neutron dose measured by the under-apron dosemeter.

JAEA Reports

Application of imaging plate to the radiation protection in the MOX fuel fabrication facility

Sagawa, Naoki; Yamazaki, Takumi; Kurosawa, Shigeyuki*; Izaki, Kenji; Mizuniwa, Harumi; Takasaki, Koji

JAEA-Technology 2010-051, 35 Pages, 2011/03

JAEA-Technology-2010-051.pdf:1.83MB

The image analysis method using a imaging plate (IP) is recent technique, and this method can get the information of radioactivity distribution by the unit of Photo Simulated Luminescence (PSL). We have investigated the PSL images obtained by measuring some plutonium samples which are radiation protection samples in order to apply imaging plate to the radiation protection at the MOX fuel facility. Plutonium spots were extracted from the PSL image extracted by the threshold, in which about 99% of the back ground was excluded, and identified by the additional requirement that the spot size is more than 40 pixels. The average background is subtracted from PSL strength of the spot area identified as Pu, and the radioactivity of the Pu spot was evaluated by multiplying the conversion calculation that is in consideration of fading.

Journal Articles

Analysis of mutagenic effect induced by ion beams for breeding of ${it Aspergillus oryzae}$

Toyoshima, Yoshiyuki*; Tanaka, Hisaki*; Akagawa, Takumi*; Yamazaki, Tatsuo*; Sato, Katsuya; Hase, Yoshihiro; Narumi, Issei

JAEA-Review 2008-055, JAEA Takasaki Annual Report 2007, P. 84, 2008/11

no abstracts in English

Journal Articles

Mutation bleeding of soy sauce brewing microorganisms using ion beams

Toyoshima, Yoshiyuki*; Tanaka, Hisaki*; Akagawa, Takumi*; Yamazaki, Tatsuo*; Sato, Katsuya; Hase, Yoshihiro; Narumi, Issei

Hoshasen To Sangyo, (119), p.22 - 26, 2008/09

no abstracts in English

Journal Articles

Analysis of mutagenic effect induced by ion beams for breeding of ${it Aspergillus oryzae}$

Toyoshima, Yoshiyuki*; Akagawa, Takumi*; Yamazaki, Tatsuo*; Sato, Katsuya; Hase, Yoshihiro; Narumi, Issei

JAEA-Review 2007-060, JAEA Takasaki Annual Report 2006, P. 93, 2008/03

no abstracts in English

Journal Articles

Present status of the negative ion based NBI system for long pulse operation on JT-60U

Ikeda, Yoshitaka; Umeda, Naotaka; Akino, Noboru; Ebisawa, Noboru; Grisham, L. R.*; Hanada, Masaya; Honda, Atsushi; Inoue, Takashi; Kawai, Mikito; Kazawa, Minoru; et al.

Nuclear Fusion, 46(6), p.S211 - S219, 2006/06

 Times Cited Count:55 Percentile:87.25(Physics, Fluids & Plasmas)

Recently, the extension of the pulse duration up to 30 sec has been intended to study quasi-steady state plasma on JT-60U N-NBI system. The most serious issue is to reduce the heat load on the grids for long pulse operation. Two modifications have been proposed to reduce the heat load. One is to suppress the beam spread which may be caused by beamlet-beamlet interaction in the multi-aperture grid due to the space charge force. Thin plates were attached on the extraction grid to modify the local electric field. The plate thickness was optimized to steer the beamlet deflection. The other is to reduce the stripping loss, where the electron of the negative ion beam is stripped and accelerated in the ion source and then collides with the grids. The ion source was modified to reduce the pressure in the accelerator column to suppress the beam-ion stripping loss. Up to now, long pulse injection of 17 sec for 1.6 MW and 25 sec for $$sim$$1 MW has been obtained by one ion source with these modifications.

Journal Articles

Recent progress of negative ion based neutral beam injector for JT-60U

Umeda, Naotaka; Yamamoto, Takumi; Hanada, Masaya; Grisham, L. R.*; Kawai, Mikito; Oga, Tokumichi; Akino, Noboru; Inoue, Takashi; Kazawa, Minoru; Kikuchi, Katsumi*; et al.

Fusion Engineering and Design, 74(1-4), p.385 - 390, 2005/11

 Times Cited Count:9 Percentile:54.78(Nuclear Science & Technology)

In negative ion based neutral beam injector (N-NBI) for JT-60U, some modifications for extent pulse duration from 10 second, which is design value, to 30 second was conducted. Main limit to prevent pulse extension was heat loads onto grounded grid in an ion source and onto beam limiter placed at 22 m from the ion source. To reduce these heat loads, beam extraction area was optimized and the limiter was changed to one which had about twice thermal capacity. As a result of these modifications, the temperature rise of the water which was cooling grounded grid could be suppressed under 40 degree, which can operate in steady state condition. The temperature rise of the limiter could be restricted to 60%. Untill now the beam pulse extended to 17 second of 1.6MW power at 366keV energy, and injection of 30 seconds will be achieved in next experiment.

Journal Articles

Progress of negative ion source improvement in N-NBI for JT-60U

Kawai, Mikito; Akino, Noboru; Ebisawa, Noboru; Grisham, L. R.*; Hanada, Masaya; Honda, Atsushi; Inoue, Takashi; Kazawa, Minoru; Kikuchi, Katsumi*; Kuriyama, Masaaki; et al.

Fusion Science and Technology, 44(2), p.508 - 512, 2003/09

 Times Cited Count:4 Percentile:32.21(Nuclear Science & Technology)

The negative ion source for negative ion based neutral beam injector(N-NBI) of JT-60U aims at generating a negative ion beam with 500 keV and 22A for 10s. The N-NBI system was completed in 1996, followed by starting the efforts to increase beam power and energy. (1)Spatial non-uniformity of the source plasma causes position-dependent divergence of a beamlet due to mis-matching of local beam perveance. A part of the divergent energetic beams is intercepted by the grids and resultantly produce the excessive heat load of the grids and/or induce the high voltage breakdown. So several techniques to take measures against and to correct the non-uniformity in these sources were implemented. (2)Correction of beamlet deflection by adjusting the electric field at the extraction grids. It improved the beam divergence and then decreased an excessive heat load of a beam limiter by more than 50 %. As a result, the maximum injection power 6.2MW and beam pulse duration 10 seconds were obtaind.

Journal Articles

Improvement of beam performance in the negative-ion based NBI system for JT-60U

Umeda, Naotaka; Grisham, L. R.*; Yamamoto, Takumi; Kuriyama, Masaaki; Kawai, Mikito; Oga, Tokumichi; Mogaki, Kazuhiko; Akino, Noboru; Yamazaki, Haruyuki*; Usui, Katsutomi; et al.

Nuclear Fusion, 43(7), p.522 - 526, 2003/07

 Times Cited Count:38 Percentile:74.79(Physics, Fluids & Plasmas)

The Negative-ion based Neutral Beam Injection System (N-NBI) for JT-60U has been operating for plasma heating and non-inductive current drive since 1996. The target is inject of neutral beam into plasma with beam energy 500 keV, injection power 10 MW, for 10 seconds. Until now pulse duration time was restricted up to 5.3 seconds because of larger heat load of port limiter. Recently from the measurement of beam profile at 3.5m downstream from the ion source, it was found that the outermost beamlets in each segment were deflected outward. It was caused by non-uniform electric field by grooves. By improving this, outermost beamlet deflection angle was decreased from 14 mrad to 4 mrad. In this result, 10 seconds injection, which is target parameter, has achieved at 355 keV, 2.6MW, while pulse length was restricted up to 5.3 seconds by larger heat load of port limiter.

Journal Articles

Present status of the negative ion based neutral beam injector for JT-60U

Oga, Tokumichi; Umeda, Naotaka; Akino, Noboru; Ebisawa, Noboru; Grisham, L. R.*; Hikida, Shigenori*; Honda, Atsushi; Ito, Takao; Kawai, Mikito; Kazawa, Minoru; et al.

Review of Scientific Instruments, 73(2), p.1058 - 1060, 2002/02

 Times Cited Count:12 Percentile:56.36(Instruments & Instrumentation)

no abstracts in English

Oral presentation

Development of breeding method for ${it Aspergillus oryzae}$ using ion beams

Toyoshima, Yoshiyuki*; Akagawa, Takumi*; Yamazaki, Tatsuo*; Ura, Tetsuji*; Sato, Katsuya; Hase, Yoshihiro; Narumi, Issei

no journal, , 

no abstracts in English

Oral presentation

Method for the selective elimination of the ${it Aspergillus oryzae}$ genes using ion beams

Toyoshima, Yoshiyuki*; Akagawa, Takumi*; Yamazaki, Tatsuo*; Sato, Katsuya; Hase, Yoshihiro; Narumi, Issei

no journal, , 

no abstracts in English

Oral presentation

Effect of ion beam irradiation on the genome structure of ${it Aspergillus oryzae}$

Toyoshima, Yoshiyuki*; Tanaka, Hisaki*; Akagawa, Takumi*; Yamazaki, Tatsuo*; Iwashita, Kazuhiro*; Mikami, Shigeaki*; Sato, Katsuya; Narumi, Issei

no journal, , 

no abstracts in English

Oral presentation

Development of Koji mold breeding using ion beams, 2; Effect of ion beam irradiation on the genome structure of ${it Aspergillus oryzae}$

Tanaka, Hisaki*; Toyoshima, Yoshiyuki*; Akagawa, Takumi*; Yamazaki, Tatsuo*; Ura, Tetsuji*; Iwashita, Kazuhiro*; Mikami, Shigeaki*; Sato, Katsuya; Narumi, Issei

no journal, , 

no abstracts in English

Oral presentation

Elimination of marker gene from transgenic ${it Aspergillus oryzae}$

Toyoshima, Yoshiyuki*; Akagawa, Takumi*; Yamazaki, Tatsuo*; Sato, Katsuya; Hase, Yoshihiro; Narumi, Issei

no journal, , 

no abstracts in English

Oral presentation

Individual dose analysis of non-uniform body and extremity exposures during glove box operations

Nakagawa, Takahiro; Takada, Chie; Tsujimura, Norio; Yamazaki, Takumi; Kashimura, Shinya*

no journal, , 

no abstracts in English

Oral presentation

Suggestion for design of ventilation system based on trend analysis of dust monitoring data under normal conditions

Yamazaki, Takumi; Izaki, Kenji; Mizuniwa, Harumi

no journal, , 

no abstracts in English

45 (Records 1-20 displayed on this page)