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-ray emitting nuclides (Joint research)Ishimori, Kenichiro; Oki, Keiichi; Takaizumi, Hirohide; Kameo, Yutaka; Oki, Yoshiyuki*; Nakashima, Mikio
JAEA-Technology 2007-065, 20 Pages, 2008/01
JAEA-Technology-2007-065.pdf:1.4MB
In order to prepare a reference material which is used for radiochemical analysis of solidified products made from non-metallic miscellaneous low level radioactive solid wastes by melting in Nuclear Science Research Institute, Japan Atomic Energy Agency, the preparation method of the reference material was investigated. Under the optimum melting conditions obtained in this report, the reference material containing 
Np, 
Am and 
Cm as -ray emitting nuclides was successfully prepared. From radiochemical analysis of the reference material, the radioactive concentration of respective nuclides was determined to be 0.188
0.001 Bq/g for Np, 0.3680.004 Bq/g for Am, 0.4020.010 Bq/g for Cm.
Nishitani, Takeo; Yamauchi, Michinori; Izumi, Mikio*; Hayakawa, Atsuro*; Ebisawa, Katsuyuki*; Kondoh, Takashi; Kusama, Yoshinori
Fusion Engineering and Design, 82(5-14), p.1192 - 1197, 2007/10
Times Cited Count：5 Percentile：37.06(Nuclear Science & Technology)no abstracts in English
Aoyama, Yoshio; Miyamoto, Yasuaki; Yamaguchi, Hiromi; Sano, Akira*; Naito, Susumu*; Sumida, Akio*; Izumi, Mikio*; Maekawa, Tatsuyuki*; Sato, Mitsuyoshi*; Nambu, Kenichi*; et al.
Proceedings of 15th International Conference on Nuclear Engineering (ICONE-15) (CD-ROM), 6 Pages, 2007/04
no abstracts in English
Naito, Susumu*; Hirata, Yosuke*; Izumi, Mikio*; Sano, Akira*; Miyamoto, Yasuaki; Aoyama, Yoshio; Yamaguchi, Hiromi
Journal of Nuclear Science and Technology, 44(2), p.121 - 128, 2007/02
Times Cited Count：1 Percentile：11.28(Nuclear Science & Technology)A reinforced ion current prediction model in the alpha radioactivity measurement using ionized air transportation was presented. Although our previous model explained a qualitative trend of the measured ion current values, their absolute values were considerably overestimated. In order to explain them quantitatively, the model was reinforced in consideration of columnar recombination. It was found that our new model explains the considerable ion loss in the initial stage of ion diffusion and narrows the gap between the predicted and measured ion current values. This model also indicated a prospective suppression of ion loss due to columnar recombination by spraying a high-speed air flow on the contaminated surface. This suppression was experimentally investigated and confirmed. In conclusion, the theoretical relationship between alpha radioactivity and ion current was clarified quantitatively in laminar flow and turbulent pipe flow.
-ray generated ion clusters in airTong, L.*; Nambu, Kenichi*; Hirata, Yosuke*; Izumi, Mikio*; Miyamoto, Yasuaki; Yamaguchi, Hiromi
Japanese Journal of Applied Physics, Part 1, 45(10B), p.8217 - 8220, 2006/10
Times Cited Count：0 Percentile：0.00(Physics, Applied)A particle model is developed using the test-particle Monte Carlo method to study the transport properties of alpha-ray generated ion clusters in a flow of air. The simulated transport properties provide a theoretical basis for designing the alpha radioactivity measurement system. An accurate ion-molecule collision model is proposed to simulate the collisions between ion and air molecule. The recombination between positive and negative ions is simulated using Nanu and Denpoh method [J. Phys. Soc. Jpn. 67(1998) 1288]. The calculations are performed from low gas pressures of 0.001 and 0.01 atm to high gas pressures of 0.1 and 1 atm in a circular pipe. The simulation presents such a steady state ion transport that the generation of ions reaches a quasi-equilibrium with the loss of ions, absorbed by a measuring sensor and lost on the pipe wall.
Naito, Susumu*; Sano, Akira*; Izumi, Mikio*; Noda, Etsuo*; Hayashi, Kazuo*; Sato, Mitsuyoshi*; Suto, Osamu; Miyamoto, Yasuaki; Kondo, Shinichi*; Iinuma, Koichi*; et al.
Nuclear Science Symposium Conference Record, 2005 IEEE, Vol.1, p.495 - 499, 2005/10
An alpha radioactivity monitor (alpha-clearance monitor) is being developed to measure alpha radioactivity of uranium contaminated waste with large and complex surfaces. It uses an alpha radioactivity measurement method by collecting the air ionized by alpha particles using an air stream and by measuring its ion current. One of the major problems of the alpha-clearance monitor is the background ion current mainly by radon in atmosphere (
700 fA), which is much larger than ion current of an alpha particle (several fA). It strongly influences on the detection limit of alpha radioactivity. In order to improve the detection limit, we developed a method to monitor the radon concentration inside the monitor without the additional radon detector. In addition, the influencing factors on the detection limit: ion mobility and ion recombination coefficient were measured and evaluated on various environmental conditions (temperature, humidity and aerosol density).
Nishitani, Takeo; Yamauchi, Michinori*; Izumi, Mikio*; Kusama, Yoshinori
JAERI-Tech 2005-047, 34 Pages, 2005/09
JAERI-Tech-2005-047.pdf:6.75MB
no abstracts in English
Okazaki, Koki*; Naito, Susumu*; Nakayama, Kunihiko*; Makino, Shunichiro*; Shigeyama, Musashi*; Kuwako, Akira*; Izumi, Mikio*; Ito, Jun*; Okada, Hisashi*; Muto, Keitaro
no journal, ,
In fast breeder reactor (FBR), it is important to detect a small sodium leak surely for safety. As the coolant sodium used in FBR is low pressure, a small leak occurs from a crack before a pipe breaks, therefore it is possible to detect a sodium leak so as to shutdown a reactor before a pipe completely breaks. The sodium leaking from piping of cooling system reacts with oxygen etc. including with the ambient gas to form aerosols. In the second coolant system of the prototype liquid metal FBR Monju, the ambient air around piping is drawn into radiative ionization detector (RID). When sodium aerosols are detected by RID, chemical analysis of aerosols and the viewing of the leak point are carried out, then sodium leak is confirmed. As the signal of RID depends on temperature strongly and RID detects the aerosols which do not include sodium, the improvements of RID are demanded for reliability. Moving fluid ionization detector (MID) and laser leak detector (LLD) have been developed to improve these points. MID can reduce the dependence for temperature of the signal strength, and LLD can detect sodium atoms which are included in aerosols by means of laser-induced breakdown spectroscopy. An experiment was carried out for validating sodium leak detection system with MID and LLD under real environment installed in the second coolant system of Monju. In the experiments, sodium was not leaked, and ambient air around piping of the secondary coolant system was introduced through actual sampling line and measured by MID and LLD. In addition a sodium level in the ambient air was measured by means of ion chromatography. The experiment showed that the background signals of MID and LLD were stable and low and that the sodium level due to the background of salinity (NaCl) contained in the ambient air was lower than three orders of magnitude than the sodium level for small sodium leak. The plant applicability of MID and RID was validated by this experiment.
Aoyama, Yoshio; Miyamoto, Yasuaki; Yamaguchi, Hiromi; Izumi, Mikio*; Naito, Susumu*; Yamamoto, Shuji*; Sano, Akira*; Nambu, Kenichi*; Takahashi, Hiroyuki*; Oda, Akinori*
no journal, ,
no abstracts in English
CIshimori, Kenichiro; Oki, Keiichi; Kameo, Yutaka; Takaizumi, Hirohide; Nakashima, Mikio; Oki, Yoshiyuki*; Isogai, Keisuke*
no journal, ,
no abstracts in English
Aoyama, Yoshio; Miyamoto, Yasuaki; Yamaguchi, Hiromi; Naito, Susumu*; Sano, Akira*; Izumi, Mikio*; Sumida, Akio*; Maekawa, Tatsuyuki*; Sato, Mitsuyoshi*; Nambu, Kenichi*; et al.
no journal, ,
Radioactive waste contaminated by Uranium has been accumulated in front-end facilities of the nuclear fuel cycle. The purpose of the present project is to develop the practical and highly efficient measurement system, which solves the above-mentioned requirements based on the innovative concept of indirect alpha radioactivity measurement using ionized air stream transportation. The ionized air by alpha particles near the waste is peeled and transported into the ion sensor by controlling air stream in the measurement system. In order to give the actual solution for this indirect measurement concept, we have to clarify various basic physics concerning with radiation ionizing process in the air, ion reaction process in the air, ion transportation process by the turbulent air flow, and measurement process in the ion sensor. For this purpose, we have to develop various analytical simulation technologies for predicting ion behavior as well as direct measurement technologies of ion spatial distribution. The final target of the project is to establish the practical and verified clearance confirmation technology based on the above-mentioned physical and technological knowledge.
-ray spectrometryHaraga, Tomoko; Kameo, Yutaka; Kimura, Atsushi; Koizumi, Mitsuo; Toh, Yosuke; Nakashima, Mikio
no journal, ,
no abstracts in English
