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Ito, Yoshifumi*; Endo, Nobuyuki*; Otani, Nobuo*
JNC TJ4440 2004-005, 430 Pages, 2005/03
JNC-TJ4440-2004-005.pdf:5.92MB
no abstracts in English
Kume, Kyo*; Otani, Nobuo*
JNC TJ4440 2004-003, 287 Pages, 2005/03
JNC-TJ4440-2004-003.pdf:26.52MB
no abstracts in English
Kume, Kyo*; Otani, Nobuo*; Tamagawa, Yoichi*
Heisei-16-Nendo Zaidan Hojin Wakasawan Enerugi Kenkyu Senta Kenkyu Seika Hokokushu, 7, p.29 - 32, 2005/00
The neutron detection systems for the measurement covering wide energy range from thermal to fast region has been successively developed. The main part of this system is made of organic scintillators (both liquid and plastic) with doped 10B, so that it should be sensitive to thermal neutrons with (n,
) reaction while it could detect signals during degrading fast neutrons within the scintillator. This principle was verified. Also another system made of inorganic crystals was verified to see the capability to be used as a neutron detector.
Kume, Kyo*; Otani, Nobuo*
JNC TJ4440 2003-007, 312 Pages, 2004/03
JNC-TJ4440-2003-007.pdf:42.33MB
Environmental neutron detection system is proposed. The main goal of this system was set to detect fast and thermal neutrons with the identical detector setup without degraders. A detector setuup for thermal neutron counting in prebious years, was developed first. Feasible study of this detector system for fast neutron counting was done, with help of Monte Carlo simulation and analysis of experiments with both a neutron source and neutron beam at an accelerator facility. In addition, B doped plastic intillator was studied for measurement of environmental neutrons. This was done through experiments with an Am-Be neutron source, with help of Monte Carlo simulation. In the meantime, possibility of the use of inorganic scintillators in neutron counting was verified, to solve the problems occuring at the long term use of the organic liquid scintillators. The detectors checked were BGO, GSO, and Nal. BGO was shown that it has little possibility for use at neutron measurement, while GSO and Nal were shown that these detectors have trivial sensitivity in neutron measurement.
Ito, Yoshifumi*; Endo, Nobuyuki*; Otani, Nobuo*
JNC TJ4440 2003-006, 408 Pages, 2004/03
JNC-TJ4440-2003-006.pdf:11.8MB
In a case of nuclear accident at nuclear facililties, strong radiations such as g-rays and neutrons might radiate at a bust in the initial stage. For the establishment of dose estimation system for such accidents, the experiments were done using the 200 MeV proton beam accelerated by synchrotron in the W-MAST. DC current mode neutron detection sysstem was tested for hegh dose neutron irradiation, where ther system was composed by NE213 scintillate, photomultiplier and pre-amp. The following results were obtained: (1) When one fast neutron was injected into NE213, the shape of pre-amp output signal wa Gaussian type with the full width of half maximum of -40ns. (2) Linear relation between the radiation intensity of neutron and the proton current was obtained in the detection system. The neutron more than 25 Mcps can be detected using this detection system with the DC current mode. In order to establish the method of the dose of radioactivity measuring using the electron spin resonance (ESR) technique, stable free-radicals generated in the tooth enamel by gamma-ray irradiation as basis research was measured with ESR equipment, precise signal analysis was performed, and the dose evaluation characteristic of having purpose at higher sensitivity was investigated. Moreover, the relationship between the dose of radioactivity and ESR signal intensity of free-radical species which were generated by X-ray irradiation, and damping behavior of the signal were evaluated about seven kinds of analogous inorganic compound to tooth enamel.
Ito, Yoshifumi*; Kume, Kyo*; Otani, Nobuo*
JNC TJ4440 2003-002, 284 Pages, 2003/03
JNC-TJ4440-2003-002.pdf:11.68MB
no abstracts in English
Ito, Yoshifumi*; Otani, Nobuo*
JNC TJ4400 2002-001, 150 Pages, 2002/03
JNC-TJ4400-2002-001.pdf:5.71MB
None
Hazama, Taira; Mori, Tomoaki; ; Aihara, Nagafumi; ; Yoshida, Mamoru; *
JNC TN9400 2001-044, 136 Pages, 2001/05
JNC-TN9400-2001-044.pdf:3.97MB
A Subcriticality measurement technique was developed to improve safety and efficiency of criticality safety control in nuclear fuel processing facilities. In the development, two measurement techniques based on reactor noise analysis were selected as candidates of subcriticality measurement technique applicable to severe situations in FBR fuel reprocessing plants. The research activity was performed in Deuterium Critical Assembly (DCA) which was partly reconstructed from the original core of the advanced thermal reactor, so that light water and FBR type fuel could be used as in the FBR fuel reprocessing plants. Through the research, each technique was improved to satisfy criteria for subcriticality monitoring technique in FBR fuel reprocessing plant. Since the two techniques have basically different features while using common devices,thier combination would be a simple and reliable measurement system. This report summarizes processes and results of the research activity in DCA.
JNC TN9440 99-005, 54 Pages, 1999/07
This data book has been conpiker for Fission Gas Plenum Streaming Experiment performed as part of the joint PNC and US DOE research program sntitled JASPER for Japanese-American Shielding Probram of Experimental Researches. The streaming experiment performed in JASPER includes five configurations comprisung typical fission gas plenum concepts of large FBR's. This data book is to cover full experimental data pertinent to the following items: experimental configurations, shield slabs, detectors, and measured data. This data book is also to cover detailed experimental program plan enabling all the information necessary to analyze the experiment and its underlying fundamentals to be available in a handy form.
Nishihara, Kenji*; Kobayashi, Keisuke*; Otani, Nobuo
Journal of Nuclear Science and Technology, 36(3), p.265 - 272, 1999/00
Times Cited Count：1 Percentile：13.12(Nuclear Science & Technology)Mori, Tomoaki;
Journal of Nuclear Science and Technology, 36(7), p.555 - 559, 1999/00
Times Cited Count：12 Percentile：66.1(Nuclear Science & Technology)None
Mori, Tomoaki;
PNC TN9410 98-056, 72 Pages, 1998/06
The sub-criticality monitoring system has been developed for criticality safety control in nuclear fuel handling plants. In the past experiments performed with the Deuterium Critical Assembly(DCA), it was confirmed that the detection of sub-criticality was possible to k
=0.3. To investigate the applicability of the method to more generalized system, experiments were performed in the light-water-moderated system of the modified DCA core. From these experiments, it was confirmed that the prompt decay constant(), which was a index of the sub-criticality, was detected between k=0.623 and k 0.870 and the difference of 0.05
0.1
k could be distinguished. The values were numerically calculated with 2D transport code TWODANT and monte carlo code KENO V.a, and the results were compared with the measured values. The differences between calculated and measured values were proved to be less than 13%, which was sufficient accuracy in the sub-criticality monitoring system. It was confirmed that Feynman- method was applicable to sub-critical measurement of the light-water-moderated system.
Mori, Tomoaki;
PNC TN9450 98-003, 118 Pages, 1998/04
The nuclear characteristics of heavy-water-moderated cluster type lattice were systematically investigated by unit cen calculation with one-dimensional Sn transport code. The results of flux distribution, energy spectrum, and void reactivity were summarized for major parameters, such as fuel type, lattice pitch, coolant and moderator.
analysisMori, Tomoaki; Otani, Nobuo
PNC TN9410 97-095, 44 Pages, 1997/11
The Feynman- method has been developed for monitoring sub-criticality in nuclear fuel facilities. It is difficult to apply the Feynman- method which estimates statistical variation of the number of neutron counts per unit time, to the system in transient condition such that the averaged neutron flux varies with time. In the application of Feynman- method to such system, it is suggested to remove the averaged variation of neutron flux from neutron count data by the use of the difference filter. In this study, we applied the difference filter to reactor noise data at sub-criticality near to criticality, where the prompt decay constant was difficult to estimate due to the large effect of delayed neutron. With the difference filter, accurate prompt decay constants for effective multiplication factors from 0.999 to 0.994 were obtained by Feynman- method. It was cleared that the difference filter is effective to estimate accurate prompt decay constant, so that there is the prospect to be able to apply Feynman- method having the difference filter to the system in the transient condition.
PNC TN9410 97-011, 45 Pages, 1997/01
In the study for the development of the sub-criticality monitoring system for the nuclear fuel facilities, wavelet analysis was applied to detect the neutron multiplication system is approaching to critical. Neutron noise signal is the measured data for the monitoring, and the data was accumulated in the multi-channel scaler of the neutron detection system. From the point of view of the simplicity of numerical calculations of the MCS data, discrete wavelet transform by using the Cardinal spline functions was selected in the varaiety of wavelet funtions. Simulated noise data of the system without neutron multiplication was numerically produced and also transformed by the wavelet analysis procedure to be compared to the results from the nutron multiplication system. The approach to the critical can be detected by checking the difference of the two kinds of transformed results, with and without neutron multiplications. The method was applied to the neutron noise signal obtained at the Deuterium Critical Assembly(DCA), and it was confirmed that approaching to critical can be detected by tbe present method.
methodOtani, N.; Hazama, Taira
Proceedings of 5th International Conference on Nuclear Criticality Safety, Vol.2, P. 11.43, 1995/00
None
Kawai, Masayoshi*; ; *; Yamano, Naoki*; *; *; *; *; Sakurai, Kiyoshi
JAERI 1330, 129 Pages, 1994/03
no abstracts in English
Haga, Kazuo; Kambe, M.; Kataoka, H.; Otani, N.; Otsubo, A.
Acta Astronautica, 26(5), p.349 - 357, 1992/05
Times Cited Count：2 Percentile：40.75(Engineering, Aerospace)None
;
PNC TN9450 91-009, 127 Pages, 1991/11
Effective neutron multiplication factors of subcritical assemblies, which will be applied to the experiments of subcriticality measurement, are estimated and summarized. Subcritical assemblies investigated here are supposed to be loaded in the subcriticality experiment system: The subcritical experiment system will be constructed by changing the core structure of Deuterium Critical Assembly, and the geometrical dimensions of investigated assemblies were selected so as the assemblies can be loaded to the experiment system. Subcriticalities or effective multiplication factors of cylindrical, slab and annular assemblies by using ATR fuel pins, FBR fuel pins or liquid uranium fuel were evaluated. The assemblies studied here have rather high multiplication factors, and the assemblies with lower multiplication factors should be added as future problem. It has been proved that the subcritical assemblies with desirable multiplication factors can be formed by the fuels mentioned above.
