Quantitative analysis method for radiation distribution in high radiation environment by gamma-ray image spectroscopy (Contract research); FY2018 Center of World Intelligence Project for Nuclear Science/Technology and Human Resource Development

Collaborative Laboratories for Advanced Decommissioning Science; Kyoto University*

JAEA-Review 2019-036, 65 Pages, 2020/03

JAEA-Review-2019-036.pdf:4.46MB

JAEA/CLADS, had been conducting the Center of World Intelligence Project for Nuclear Science/Technology and Human Resource Development (hereafter referred to "the Project") in FY2018. The Project aims to contribute to solving problems in nuclear energy field represented by the decommissioning of the Fukushima Daiichi Nuclear Power Station, Tokyo Electric Power Company Holdings, Inc. For this purpose, intelligence was collected from all over the world, and basic research and human resource development were promoted by closely integrating/collaborating knowledge and experiences in various fields beyond the barrier of conventional organizations and research fields. The sponsor of the Project was moved from the Ministry of Education, Culture, Sports, Science and Technology to JAEA since the newly adopted proposals in FY2018. On this occasion, JAEA constructed a new research system where JAEA-academia collaboration is reinforced and medium-to-long term research/development and human resource development contributing to the decommissioning are stably and consecutively implemented. Among the adopted proposals in FY2018, this report summarizes the research results of the "Quantitative Analysis Method for Radiation Distribution in High Radiation Environment by Gamma-ray Image Spectroscopy". Electron-tracking Compton camera (ETCC) has been developed originally for nuclear gamma-ray astronomy, and also applied to medical use as a technology that greatly improves the resolution of conventional Compton camera by measuring three-dimensional tracking of electrons using a gaseous 3-dimensional position detector (so called Time Projection Chamber) in the first stage. In the present study, based on the ETCC that has been developed for medical use, we produce a prototype of light weight ETCC with the emphasis on the operability at the site, and evaluate its practicability by field tests.

Establishment of a novel detection system for measuring primary knock-on atoms

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

Proceedings of 2017 IEEE Nuclear Science Symposium and Medical Imaging Conference (NSS/MIC 2017) (Internet), 3 Pages, 2018/11

https://doi.org/10.1109/NSSMIC.2017.8532975

The energy spectra of primary knock-on atoms (PKAs) are essential for radiation damage assessment in design of accelerator facilities. However up to date the experimental data are still limited, due to the poor mass resolution and the high measurement threshold energies in the conventional setup of nuclear physics experiments using solid state detectors, which are typically above a few MeV/nucleon. In this study, a novel detection system consisting of two time detectors and one dE-E energy detector is proposed and being constructed to measure the PKA spectra. The system and detector design was based on Monte Carlo simulations by using the PHITS code. The PHITS simulations show that the system is able to distinguish the PKA isotopes above 0.2-0.3 MeV/nucleon for A=2030 amu; the PKA mass identification thresholds decrease to 0.1 MeV/nucleon for PKAs lighter than 20 amu. The detection system will be tested in the summer of 2017, and the test results will be presented at the conference.

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

https://doi.org/10.1063/1.1785261

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 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.

Development of a high-performance microstrip gas chamber with a capability of track discrimination for neutron detection

Nakamura, Tatsuya; Yamagishi, Hideshi; Masaoka, Sei; Soyama, Kazuhiko; Aizawa, Kazuya

Nuclear Instruments and Methods in Physics Research A, 529(1-3), p.336 - 341, 2004/08

https://doi.org/10.1016/j.nima.2004.05.008

A microstrip gas chamber (MSGC) with a capability of track discrimination for neutron detection was developed whilst ensuring the stability of the MSGC and fulfilling the specifications required for detectors using in high-flux reactors and high-intensity pulsed-neutron sources. The developed two-dimensional detector system comprises a MSGC with individual signal channel read-outs and a new instrument system with a capability of secondary-particle discrimination (InSPaD). The InSPaD identifies the particles -proton and triton- created in the nuclear reaction by a simple, fast and cost-effective method using the difference in the track length, and it enables a small amount of heavy gas such as with helium-3 to be used as the filling gas whilst achieving a high spatial resolution.

Measurement of absolute intensity for high energy SR photons using calorimeter

Asano, Yoshihiro; Kishi, Noriyuki*; Moriya, Takahiro*

AIP Conference Proceedings 705, p.564 - 567, 2004/00

https://doi.org/10.1063/1.1757859

no abstracts in English

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 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$, but it became over than 40% for the rapid power change with the reactivity of about 3$.

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 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.

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

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

Calibration of surveymeters for dose estimation with -ray sources simulating skin contamination

Yoshida, Makoto;

Hoken Butsuri, 28, p.187 - 193, 1993/00

https://doi.org/10.5453/jhps.28.187

no abstracts in English