Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Yamamoto, Akio*; Endo, Tomohiro*; Chiba, Go*; Tada, Kenichi
Nuclear Science and Engineering, 196(11), p.1267 - 1279, 2022/11
Times Cited Count：1 Percentile：31.61(Nuclear Science & Technology)The resonance upscattering effect (the thermal agitation effect) is incorporated in the generation capability of multi-group neutron cross sections of the FRENDY nuclear data processing system. The resonance upscattering effect is considered by (1) the variation of self-shielding factors (effective cross sections) due to the change in ultra-fine group spectrum and (2) the variation of group-to-group elastic scattering cross sections. In the verification calculations, impacts on the ultra-fine group spectrum, effective cross sections, and neutronics characteristics (the Doppler effect) are confirmed. The effect of energy group structure and the treatments of resonance upscattering on the Doppler effect through the variation of effective cross sections and the elastic scattering matrix are studied. The results indicate that the FRENDY can provide appropriate multi-group cross sections considering the resonance upscattering effect.
Yamamoto, Akio*; Endo, Tomohiro*; Tada, Kenichi
Journal of Nuclear Science and Technology, 58(12), p.1343 - 1350, 2021/12
Times Cited Count：1 Percentile：16.35(Nuclear Science & Technology)An adaptive setting method of background cross sections is implemented to FRENDY/MG, which is a multi-group neutron cross section generation code. In the present adaptive setting method, the range of background cross section is initially divided into 10 equal intervals and unnecessary background cross section points, at which self-shielding factors or reaction rates can be accurately interpolated, are eliminated. If the interpolation accuracy in an interval is not sufficient, the interval is successively halved until sufficient interpolation accuracy is obtained. For accurate interpolation of self-shielding factor or reaction rates, the monotone cubic interpolation is used. Verification calculations are carried out for all isotopes in JENDL-4.0 and -4.0u. Calculation results indicate that typical numbers of background cross sections are from 10 to 25 when the monotone cubic interpolation and error tolerance of 0.01 for self-shielding factors are used.
Fukaya, Yuji; Goto, Minoru; Ohashi, Hirofumi
Annals of Nuclear Energy, 138, p.107182_1 - 107182_9, 2020/04
Times Cited Count：0 Percentile：0.01(Nuclear Science & Technology)The investigation on self-shielding effect of double heterogeneity for plutonium burner High Temperature Gas-cooled Reactor (HTGR) design has been performed. Plutonium burner HTGR designed in the previous study by using the advantage of double heterogeneity to control excess reactivity. In the present study, the mechanism of the self-shielding effect is elucidated by the analysis of burn-up calculation and reactivity decomposition based on exact perturbation theory. As a result, it is revealed that the characteristics of burn-up reactivity are determined by resonance cross section peak at 1 eV of 
Pu due to the surface term of background cross section, this is, the characteristics of neutron leakage from fuel lump and collision to a moderator. Moreover, significant spectrum shift is caused during the burn-up period, and it enhances reactivity worth of 
Pu and Pu in EOL.
Oigawa, Hiroyuki; Ando, Masaki; Iijima, Susumu; Takaki, Naoyuki*; Uematsu, Mari Marianne*
JAERI-Research 2001-036, 48 Pages, 2001/06
JAERI-Research-2001-036.pdf:2.38MB
no abstracts in English
*
JNC TJ9400 2000-009, 63 Pages, 2000/02
JNC-TJ9400-2000-009.pdf:2.48MB
The present status of nuclear data for technetium (Tc)-99, which is a well-known fission product (FP), has been reviewed and investigated. And making use of the Kyoto university Lead Slowing-down Spectrometer (KULS), the cross section of the 
Tc (n, 
) 
Tc reaction has been measured in the energy range from thermal to keV neutron energy with an Ar-gas proportinal counter. The neutron flux/spectrum has been monitored with a BF
proportional counter, and the relative measurement has been normalized to the well-known standard capture cross section value for the Tc (n, ) Tc reaction at 0.0253 eV. Self-shielding corrections, especially near the resonance peaks, were made by the calculations with the MCNP code. Although the experimental data measured by Chou et al with a lead slowing-down spectrometer are higher in general, the energy dependency is similar to the present measurement. The evaluated data in ENDF/B-VI and JENDL-3.2 are higher near the resonances at 5.6 and 20 eV and above several 100 eV. A lead slowing-down spectrometer was installed coupled to a 46 MeV electron linac at the Research Reactor Institute, Kyoto university (KURRI). Characteristics of the Kyoto University Lead Slowing-down Spectrometer (KULS) were measured and (1)the relation between neutron slowing-down time t(
s) and energy E(keV) (E=190/t
in Bi hole and E=156/t in Pb hole) and (2)the energy resolution (
40% in Bi and Pb holes) were experimentally investigated. (3)The neutron energy spectrum in the KULS was also measured by the neutron TOF method. The results obtained by the MCNP code were in general agreement with these experimental ones.
*; Kitada, Takanori*; Tagawa, Akihiro; *; Takeda, Toshikazu*
JNC TJ9400 2000-006, 272 Pages, 2000/02
JNC-TJ9400-2000-006.pdf:9.69MB
Investigation was made on the follwing three themes as a part of the improvement of reactor physics analysis method for FBR with various core concept. Part 1: Investigation of Error Estimation of Neutron Spectra in FBR and Suggestions to Improve the Accuracy. In order to improve the spectrum unfolding method used in fast experimental reactor JOYO, a trial was made to evaluate the error in the estimated neutron spectrum, cause by cause. And the evaluated errors were summed up to obtain the most probable and reasonable error as possible. The summed up error was found relatively small compared to the error caused by the uncertainty of cross section data: most of the error in the spectrum unfolding method can be attributed to the error in cross sections. It was also found that the error due to the fission spectrum causes a considerable error in the high energy neutron spectrum which is over several MeV. Part 2: Study on Reactor Physics Analysis Method for Gas-Cooled FBR. In gas-cooled FBR, the portion of coolant channels in core volume is larger than sodium-cooled FBR. This leads to strong neutron streaming effects. For sodium-cooled FBR, several methods were proposed to evaluate the neutron streaming effect, however, these methods can not be used directly to gas-cooled reactor because the direction dependent diffusion coefficient becomes infinitive along the direction pararel to the coolant chammel. In this study, a new method is proposed to evaluate the neutron streaming effect, based on the method taking the axial buckling into consideration, which method was originally proposed by K
hler. Part 3: Study on Reactor Physics Analysis Method for Water-Cooled FBR An investigation was made on low-moderated water-cooled FBR, on the point that the ordinary used analysis method for FBR may give considerable difference in results in such core. In light water reactors, it is well known that the space dependence of self-shielding effect of heavy nuclides are considerably ...
Dietze, K.
JNC TN9400 99-089, 20 Pages, 1999/11
The integral experiments performed at the Rossendorf fast-thermal coupled reactor RRR/SEG have been reanalyzed using the JNC route for reactor calculation JENDL3.2/SLAROM / CITATION / JOINT / PERKY. The Rossendorf experiments comprise sample reactivity measurements with pure fission products and structural material in five configurations with different neutron and adjoint spectra. The shapes of the adjoint spectra have been designed to get high sensitivities to neutron capture or the scattering effect. The calculated neutron and adjoint spectra are in good agreement with former results obtained with the European route JEF2.2/ECCO/ERANOS. The C/E-values of the central reactivity worths of samples under investigation are given. Deviations in the results of both routes are due to the different libraries, codes, and self-shielding treatments used in the calculations. Results outside of the error are discussed.
Sakamoto, Yukio; *; Nakane, Yoshihiro; ; ; Tanaka, Shunichi
SATIF-2: Shielding Aspects of Accelerators,Targets and Irradiation Facilities, 0, p.147 - 156, 1996/00
no abstracts in English
Haruyama, Yasuyuki; Yotsumoto, Keiichi; Okamoto, Jiro
JAERI-M 93-114, 46 Pages, 1993/06
no abstracts in English
Pufrom transmission measurements in the energy range of 1500 keVH.Derrien*
Journal of Nuclear Science and Technology, 29(8), p.794 - 804, 1992/08
no abstracts in English
35keVOigawa, Hiroyuki; Fujita, Yoshiaki*; *; Yamamoto, Shuji*; Kimura, Itsuro*
Journal of Nuclear Science and Technology, 28(10), p.879 - 893, 1991/10
no abstracts in English
JAERI-M 89-074, 109 Pages, 1989/06
no abstracts in English
Takeda, Toshikazu*; Ito, Noboru*; Kugo, Teruhiko*; Takamoto, Masanori*; Aoki, Shigeaki*; Kawagoe, Yoshihiro*; Sengoku, Katsuhisa*; Tanaka, Motonari*; Yoshimura, Akira*; Tamitani, Masashi*; et al.
PNC TJ2605 89-001, 251 Pages, 1989/03
no abstracts in English
; *
Nuclear Science and Engineering, 77, p.250 - 256, 1981/00
Times Cited Count：0 Percentile：0.27(Nuclear Science & Technology)no abstracts in English
; ; *
JAERI 1267, 42 Pages, 1980/09
no abstracts in English
; *;
JAERI-M 7724, 78 Pages, 1978/06
no abstracts in English
;
Nihon Genshiryoku Gakkai-Shi, 12(1), p.2 - 6, 1970/00
no abstracts in English
Ueki, Taro
no journal, ,
In this excerpt, it is shown that the delta-tracking combined with a voxel mesh and an index search is an efficient tool for the reactor physics analysis of random media. The essential idea is the use of delta-tracking in a selected region consisting of a base material where voxel mesh is overlaid, a particle flights by ignoring the mesh cell boundaries, and a fast index search is applied at the flight destination to identify where the particle is. It turns out that computational time remains the same over numbers of voxel mesh cells from the fourth power of ten to the eleventh power of ten. Numerical results are demonstrated in terms of the criticality analysis of the random substitution of SUS304 in fuel debris.
