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Journal Articles

First measurement of time-resolved neutron yield on JT-60U using a microfission chamber

Hayashi, Takao; Nishitani, Takeo; Ishikawa, Masao

Review of Scientific Instruments, 75(10), p.3575 - 3577, 2004/10

 Times Cited Count:10 Percentile:49.94(Instruments & Instrumentation)

Micro fission chambers, which are pencil sized ionization chamber with fissile material inside, to be installed in the vacuum vessel as neutron monitor for the International Thermonuclear Experimental Reactor (ITER). The micro fission chamber has been installed inside toroidal field coils in JT-60U, in order to investigate the technical validity as neutron monitor in a magnetic field of about 2 T. Compared with the neutron yield measured by three $$^{235}$$U fission chambers which are used as neutron monitors in JT-60U, neutron yield measured by micro fission chamber has a good linearity with them. The influence of the magnetic field on the micro fission chamber has not been observed. However improper signals caused by plasma disruption and breakdown event of Neutral Beam Injection were observed, probably due to long wiring between the detector and the preamplifier. Therefore, by enhancement of noise protections, micro fission chambers can be available as neutron monitor for ITER.

JAEA Reports

Measurements of power profile in TRACY supercritical experiment by detecting epithermal neutrons

Nakajima, Ken; Yanagisawa, Hiroshi; Miyoshi, Yoshinori

JAERI-Tech 2003-028, 31 Pages, 2003/03

JAERI-Tech-2003-028.pdf:1.38MB

We have tried to measure the power profile in the TRACY supercritical experiment with high accuracy by detecting epithermal neutrons. In order to measure the epithermal neutrons, a cadmium covered $$^{235}$$U fission chamber was used, and polyethylene, a neutron moderator, was set inside the cadmium to enhance the neutron detection efficiency. In addition, a lead shield was used to reduce the noise current due to gamma-rays. The measured results were compared with the ones using a thermal neutron detector, and it was found that the time delay effect in the thermal neutron detection, which was caused by the flight time of neutrons to reach the detector, distorted the power profile and reduced its peak value. The reduction ratio of peak power was about 4% for the relatively slow power change with the inserted reactivity of 1.5$, but it became over than 40% for the rapid power change with the reactivity of about 3$.

JAEA Reports

Design of ex-vessel neutron monitor for ITER

Nishitani, Takeo; Iguchi, Tetsuo*; Ebisawa, Katsuyuki*; Yamauchi, Michinori*; Walker, C.*; Kasai, Satoshi

JAERI-Tech 2002-062, 39 Pages, 2002/07

JAERI-Tech-2002-062.pdf:1.65MB

no abstracts in English

JAEA Reports

Performance test of micro-fission chambers for in-vessel neutron monitoring of ITER

Yamauchi, Michinori*; Nishitani, Takeo; Ochiai, Kentaro; Morimoto, Yuichi*; Hori, Junichi; Ebisawa, Katsuyuki*; Kasai, Satoshi

JAERI-Tech 2002-032, 41 Pages, 2002/03

JAERI-Tech-2002-032.pdf:2.62MB

A micro-fission chamber and a dummy chamber without uranium were fabricated and the performance was tested. They are designed to be installed inside the vacuum vessel of compact ITER (ITER-FEAT) for neutron monitoring. Vacuum leak rate of the chamber, resistances between central conductor and outer sheath, and mechanical strength up to 50G acceleration were confirmed to meet design criteria. Gamma-ray sensitivity was measured with $$^{60}$$Co gamma-ray irradiation facility at JAERI Takasaki. The output signals for gamma-rays in Campbelling mode were estimated to be less than 0.1% those by neutrons at the location behind the blanket module in ITER-FEAT. Detector response for 14 MeV neutrons was investigated with the FNS facility. Excellent linearity between count rates and neutron fluxes was confirmed. According to the test for the change of surrounding materials, the sensitivity was enhanced by slow-downed neutrons, which agreed with the calculation result by MCNP-4C code. As a result, it was concluded that the developed micro-fission chamber is applicable for ITER-FEAT.

JAEA Reports

Design of in-vessel neutron monitor using micro fission chambers for ITER

Nishitani, Takeo; Ebisawa, Katsuyuki*; Walker, C.*; Kasai, Satoshi

JAERI-Tech 2001-066, 57 Pages, 2001/10

JAERI-Tech-2001-066.pdf:1.89MB

no abstracts in English

JAEA Reports

An Investigation of methods for neutron dose measurement in high temperature irradiation fields

Kosako, Toshiso*; Sugiura, Nobuyuki*; Kudo, Kazuhiko*; Mori, Chizuo*; Iimoto, Takeshi*; Shikama, Tatsuo*; Katagiri, Masaki; Hayashi, Kimio; Aihara, Jun; Shibata, Taiju; et al.

JAERI-Review 2000-017, 78 Pages, 2000/10

JAERI-Review-2000-017.pdf:4.62MB

no abstracts in English

Journal Articles

Neutron monitor using microfission chambers for the international thermonuclear experimental reactor

Nishitani, Takeo; L.C.Johnson*; Ebisawa, Katsuyuki*; C.Walker*; Ando, Toshiro; Kasai, Satoshi

Review of Scientific Instruments, 70(1), p.1141 - 1144, 1999/01

 Times Cited Count:14 Percentile:67.27(Instruments & Instrumentation)

no abstracts in English

Journal Articles

In-Vessel neutron monitor using micro fission chambers for ITER

Nishitani, Takeo; Ebisawa, Katsuyuki*; C.Walker*; *; Kasai, Satoshi; L.C.Johnson*

Proc. of Int. Workshop on Diagnostics for Experimental Fusion Reactors, p.491 - 500, 1998/00

no abstracts in English

Journal Articles

Design of ITER neutron yield monitor using microfission chambers

Nishitani, Takeo; Ebisawa, Katsuyuki*; Iguchi, Tetsuo*; Matoba, Toru

Fusion Engineering and Design, 34-35, p.567 - 571, 1997/00

 Times Cited Count:12 Percentile:68.84(Nuclear Science & Technology)

no abstracts in English

Journal Articles

Absolute calibration of the JT-60U neutron monitors using a $$^{252}$$Cf neutron source

Nishitani, Takeo; Takeuchi, Hiroshi; Kondoh, Takashi; Ito, Takao*; Kuriyama, Masaaki; Ikeda, Yujiro; Iguchi, Tetsuo*; Barnes, C. W.*

Review of Scientific Instruments, 63(11), p.5270 - 5278, 1992/11

 Times Cited Count:74 Percentile:97.11(Instruments & Instrumentation)

no abstracts in English

JAEA Reports

Absolute calibration of the neutron yield measurement on JT-60 Upgrade

Nishitani, Takeo; Takeuchi, Hiroshi; Barnes, C. W.*; Iguchi, Tetsuo*; Nagashima, Akira; Kondoh, Takashi; Sakasai, Akira; Itami, Kiyoshi; Tobita, Kenji; Nagashima, Keisuke; et al.

JAERI-M 91-176, 23 Pages, 1991/10

JAERI-M-91-176.pdf:1.08MB

no abstracts in English

JAEA Reports

Journal Articles

Absolute fission-rate distribution in graphite-reflected lithium oxide blanket assembly

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Journal of Nuclear Science and Technology, 16(5), p.377 - 379, 1979/00

 Times Cited Count:11

no abstracts in English

Journal Articles

Measurement of the ratio of fission product gamma activities from $$^{2}$$$$^{3}$$$$^{9}$$Pu and $$^{2}$$$$^{3}$$$$^{5}$$U fissions

Journal of Nuclear Science and Technology, 10(9), p.560 - 565, 1973/09

no abstracts in English

Oral presentation

Establishment of a new detection system for measuring primary knock-on atoms and fission fragments

Tsai, P.-E.; Iwamoto, Yosuke; Hagiwara, Masayuki*; Sato, Tatsuhiko; Satoh, Daiki; Ito, Masatoshi*; Watabe, Hiroshi*

no journal, , 

A new detection system has been designed and constructed dedicating for the measurements of primary knock-on atoms and fission fragments, whose cross sections are critical in the design of accelerator driven systems. The detection system consists of two fast timing detectors and one dE-E energy detector. The particle species are identified by two relationships: the time-of-flight (ToF) vs E and dE vs E, and then the kinetic energy of the identified particles can be derived from the ToF. The PHITS Monte Carlo simulation code was employed for designing detectors and estimating the performance of the detection system. The new detection system will be tested at the JAEA Tandem Facility and the Cyclotron and Radioisotope Center (CYRIC) at the Tohoku University in 2017. The preliminary test results along with the PHITS simulations will be presented at the Workshop.

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