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Tanimura, Yoshihiko; Saegusa, Jun; Yoshizawa, Michio; Yoshida, Makoto
Nuclear Instruments and Methods in Physics Research A, 547(2-3), p.592 - 600, 2005/08
Times Cited Count：11 Percentile：61.23(Instruments & Instrumentation)The moderator structure of a neutron spectrometer was optimized with a Monte Carlo code of MCNP-4B. The spectrometer consists of a cylindrical moderator and a position-sensitive thermal neutron detector. It can obtain an energy spectrum from thermal neutron distribution along the cylindrical axis of the moderator. The structure of the moderator was improved by putting a low hydrogen density material in the front of a high hydrogen density one and inserting a neutron absorber which eliminated thermal neutrons diffusing in the moderator. These improvements make energy resolution of the spectrometer better especially for the low energy neutrons from a few tens to 100 keV. The designed spectrometer can be applied to the measurement of energy spectrum over a neutron energy range from a few keV to 20 MeV.
Takahashi, Fumiaki; Endo, Akira; Yamaguchi, Yasuhiro
Journal of Nuclear Science and Technology, 42(4), p.378 - 383, 2005/04
Times Cited Count：3 Percentile：23.81(Nuclear Science & Technology)Experiments were made to verify a dose assessment method from activated sodium in body in criticality accidents. A phantom containing sodium chloride solution was irradiated in the Transient Experiment Critical Facility to simulate activation of sodium. Monte Carlo calculations were performed to obtain quantitative relation between the activity of induced Na-24 and neutron dose in the phantom. In the previous work, conversion coefficients from specific activity of induced Na-24 to neutron dose had been analyzed with the MCNP-4B code concerning neutron spectra at some hypothesized configurations. One of the prepared coefficients was applied to evaluate neutron dose from the measured activity. The estimated dose agreed with the dose analyzed by the Monte Carlo calculation in the present study within an acceptable uncertainty, which is indicated by the IAEA. In addition, the dose calculated with the prepared coefficient was close to the result measured with dosimeters. These results suggest that the prepared coefficients can be applied to dose assessments from induced Na-24 in body.
Yoshida, Shigeo*; Nishitani, Takeo; Ochiai, Kentaro; Kaneko, Junichi*; Hori, Junichi; Sato, Satoshi; Yamauchi, Michinori*; Tanaka, Ryohei*; Nakao, Makoto*; Wada, Masayuki*; et al.
Fusion Engineering and Design, 69(1-4), p.637 - 641, 2003/09
Times Cited Count：9 Percentile：52.70(Nuclear Science & Technology)no abstracts in English
-ray measurements on the D-T neutron skyshine experimentsTanaka, Ryohei*; Ochiai, Kentaro; Nakao, Makoto*; Yamauchi, Michinori*; Hori, Junichi; Wada, Masayuki*; Sato, Satoshi; Nishitani, Takeo
JAERI-Tech 2003-063, 62 Pages, 2003/07
JAERI-Tech-2003-063.pdf:3.41MB
no abstracts in English
Kuroishi, Takeshi; Hoang, A.; Nomura, Yasushi; Okuno, Hiroshi
JAERI-Tech 2003-021, 60 Pages, 2003/03
JAERI-Tech-2003-021.pdf:4.56MB
The reactivity effect of the asymmetry of axial burnup profile is studied for PWR spent fuel transport cask proposed in OECD/NEA Phase II-C benchmark. The axial burnup profiles are based on in-core flux measurements. Criticality calculations are performed with the continuous energy Monte Carlo code MCNP-4B2 and the nuclear data library JENDL-3.2. Calculations are carried out not only for cases in the benchmark but also for symmetric burnup cases. Both actinide-only approach and actinide plus fission product approach is considered. The end effect is more sensitive to higher burnup asymmetry. The axial fission distribution becomes strongly asymmetric as its peak shifts toward the fuel top end. The peak of fission distribution gets higher with the increase of either the burnup asymmetry or the assembly-averaged burnup. The conservatism of uniform axial burnup assumption for the actinide-only approach is estimated quantitatively in comparison with the keff result calculated with experiment-based strongest asymmetric axial burnup profile for the actinide plus fission product approach.
Takahashi, Fumiaki; Yamaguchi, Yasuhiro
Radioisotopes, 52(2), p.94 - 97, 2003/02
Effect of phantom material on backscattered radiations was studied for photon irradiation. Monte Carlo calculations using MCNP-4B code were performed to analyze scattered radiation on the surface of 30x30x15cm3 slab phantoms with different material. Dose on the surface of a human body was also estimated with a modified MIRD-5 type phantom. No significant difference of dose due to scattered radiation was observed between a soft tissue slab and phantom the water-filled slab phantom recommended by the International Organization for Standardization. On the other hand, dose on the surface of the PMMA phantom was found to be larger than doses on the phantom with water or soft tissue. The results also showed that response of dosimeter on the ISO phantom would be near to that on the trunk of a human body.
Takahashi, Fumiaki; Endo, Akira; Yamaguchi, Yasuhiro
Radiation Protection Dosimetry, 106(3), p.197 - 206, 2003/00
Times Cited Count：4 Percentile：31.23(Environmental Sciences)Some data were derived using recent sophisticated methods to convert rapidly specific activity of induced sodium-24 to average dose over a whole body in criticality accidents. Monte Carlo calculations using the MCNP-4B code were performed to study energy spectra of neutrons and gamma rays for some criticality systems with fissile uranium. Absorbed dose to human body and activation of sodium were also analysed against external radiation by simulations using a phantom. It was found that neutron dose assessment from induced 
Na would be important to give an initial guidance of a treatment. The condition of neutron exposure, however, did not influence the quantitative relation dose by gamma rays induced within a body and activity of Na. Analyses were made to clarify the dependence of conversion from Na specific activity to dose on the orientation and the size of human body. This study suggested that the size of uranium solution and material around the fuel should be informed to properly estimate dose against external photons from neutron dose.
Li glass scintillator for wide energy rangeKim, E.; Endo, Akira; Yamaguchi, Yasuhiro; Yoshizawa, Michio; Nakamura, Takashi*; Rasolonjatovo, D. R. D.*
Nihon Genshiryoku Gakkai Wabun Rombunshi, 1(3), p.317 - 319, 2002/09
no abstracts in English
Nishitani, Takeo; Ebisawa, Katsuyuki*; Walker, C.*; Kasai, Satoshi
JAERI-Tech 2002-033, 40 Pages, 2002/03
JAERI-Tech-2002-033.pdf:1.54MB
no abstracts in English
Saegusa, Jun
Hokeikyo Nyusu, (28), p.2 - 5, 2001/10
no abstracts in English
Sakurai, Kiyoshi; Ueki, Kotaro*; Naito, Yoshitaka*
Nihon Genshiryoku Gakkai-Shi, 43(3), p.219 - 220, 2001/03
no abstracts in English
Sakurai, Kiyoshi; Kume, Etsuo; Yatabe, Shigeru*; Maekawa, Fujio; Yamamoto, Toshihiro; Nagaya, Yasunobu; Mori, Takamasa; Ueki, Kotaro*; Naito, Yoshitaka*
JAERI-Review 2000-034, 133 Pages, 2001/02
JAERI-Review-2000-034.pdf:7.69MB
no abstracts in English
