Convergence behavior of statistical uncertainty in probability table for cross section in unresolved resonance region

Tada, Kenichi; Endo, Tomohiro*

Journal of Nuclear Science and Technology, 60(11), p.1397 - 1405, 2023/11

https://doi.org/10.1080/00223131.2023.2204102

The probability table method is a well-known method for addressing self-shielding effects in the unresolved resonance region. A long computational time is required to generate the probability table. The effective way to reduce the generation time of the probability table is the reduction of the number of ladders. The purpose of this study is the estimation of the optimal number of ladders using the statistical uncertainty in the probability table. To this end, the statistical uncertainty quantification method of the probability table was developed and the convergence behavior of the statistical uncertainty was investigated. The product of the probability table and the average cross section was considered the target of the statistical uncertainty. The convergence rate was affected by the average level spacing and reduced neutron width. The generation time of the probability table was less than half when the input parameter was changed from the number of ladders to the tolerance value.

Toward a more reliable evaluation of fuel fracture during LOCA; Development of uncertainty quantification methodology and evaluation of the effect of fuel burnup extension

Narukawa, Takafumi

Nihon Genshiryoku Gakkai-Shi ATOMO, 63(11), p.780 - 785, 2021/11

https://doi.org/10.3327/jaesjb.63.11_780

no abstracts in English

Challenges for enhancing Fukushima environmental resilience, 10; Dose evaluation and risk communication

Saito, Kimiaki; Takahara, Shogo; Uezu, Yasuhiro

Nihon Genshiryoku Gakkai-Shi ATOMO, 60(2), p.111 - 115, 2018/02

no abstracts in English

Development of an evaluation methodology for the natural circulation decay heat removal system in a sodium cooled fast reactor

Watanabe, Osamu*; Oyama, Kazuhiro*; Endo, Junji*; Doda, Norihiro; Ono, Ayako; Kamide, Hideki; Murakami, Takahiro*; Eguchi, Yuzuru*

Journal of Nuclear Science and Technology, 52(9), p.1102 - 1121, 2015/09

https://doi.org/10.1080/00223131.2014.994049

A natural circulation (NC) evaluation methodology has been developed to ensure the safety of a sodium-cooled fast reactor (SFR) of 1500MW adopting the NC decay heat removal system (DHRS). The methodology consists of a 1D safety analysis which can evaluate the core hot spot temperature taking into account the temperature flattening effect in the core, a 3D fluid flow analysis which can evaluate the thermal-hydraulics for local convections and thermal stratifications in the primary system and DHRS, and a statistical safety evaluation method. The safety analysis method and the 3D analysis method have been validated using results of a 1/10 scaled water test simulating the primary system of the SFR and a 1/7 scaled sodium test simulating the primary system and the DHRS, and the applicability of the safety analysis for the SFR has been confirmed by comparing with the 3D analysis. Finally, a statistical safety evaluation has been performed for the SFR using the safety analysis method.

JENDL photonuclear data file

Kishida, Norio*; Murata, Toru*; Asami, Tetsuo*; Kosako, Kazuaki*; Maki, Koichi*; Harada, Hideo*; Lee, Y.*; Chang, J.*; Chiba, Satoshi; Fukahori, Tokio

AIP Conference Proceedings 769, p.199 - 202, 2005/05

https://doi.org/10.1063/1.1944989

Nuclear data for photonuclear reactions are required in the field of shielding design of high-energy electron accelerators and high-energy -ray therapy. The JENDL Photonuclear Data File was prepared by a working group on nuclear data evaluations for photonuclear reactions in Japanese Nuclear Data Committee. From a survey of many literatures, it is difficult to construct the photonuclear data file by using only measured data, since there are not sufficient experimental data. We were therefore evaluating with theoretical calculations based on statistical nuclear reaction models. The photonuclear cross sections that are to be contained in the file are as follows: photoabsorption cross sections, yield cross sections and DDX for neutrons, protons, deuterons, tritons, He-particles and alpha-particles, and isotope production cross sections. For the actinide nuclides, photofission cross sections are also included. The maximum energy of incident photons is 140 MeV and stored are the photonuclear data for 68 nuclides from H to Np.

Searching for pattern-forming asynchronous cellular automata; An Evolutionary approach

Suzudo, Tomoaki

Lecture Notes in Computer Science 3305, p.151 - 160, 2004/00

This paper discuss a class of 2-dimensional asynchronous cellular automata with conservation of mass, for the formation of patterns in groups. The previous study reported a methodology of searching, automatically, for pattern-forming cellular automata using a genetic algorithm; this approach successfully found a few types of pattern-forming rules. The current study is a series of statistical analyses of one of the classes found by the above methodology, with the hope of understanding the mechanisms of the pattern formation. These analyses lead to some basic logic necessary to the pattern formation, but not to enough information to elucidate the whole mechanism of the pattern formation. This result suggests that the existence of unidentified cooperative operations between the different transitions of the cellular automaton rule to carry out the pattern formation.

Nuclear data evaluation for Pu, Pu, Pu, Pu and Pu irradiated by neutrons and protons at the energies up to 250 MeV

Konobeyev, A. Y.; Fukahori, Tokio; Iwamoto, Osamu

JAERI-Research 2002-029, 48 Pages, 2002/12

JAERI-Research-2002-029.pdf:1.53MB

The evaluation of nuclear data for plutonium isotopes with atomic mass number from 238 to 242 has been performed. Neutron data were obtained at the energies from 20 to 250 MeV and combined with JENDL-3.3 data at 20 MeV. Evaluation of the proton data has been done from 1 to 250 MeV. The coupled channel optical model was used to obtain angular distributions for elastic and inelastic scattering and transmission coefficients. Pre-equilibrium exciton model and Hauser-Feshbach statistical model were used to describe neutron and charged particles emission from the excited nuclei. These evaluation is the first work for producing the full set of evaluated file up to 250 MeV for plutonium isotopes.

Evaluation of neutron-induced reactions on Pu for JENDL-3.3

Iwamoto, Osamu; Nakagawa, Tsuneo

JAERI-Research 2002-013, 18 Pages, 2002/07

JAERI-Research-2002-013.pdf:0.7MB

Cross sections and energy-angular distributions of emitted neutrons were evaluated for the neutron-incident reactions on Pu in the incident energy range of 10eV to 20MeV by using a statistical model combined with a coupled channel optical model. The calculated results were compiled to the latest evaluated nuclear data library JENDL-3.3 in the ENDF-6 format. The unresolved resonance region is assumed to be from 10eV to 30keV, and the averaged resonance parameters were obtained to reproduce the calculated cross sections. Maxwell temperatures for fission neutron spectra were estimated from a systematics with a correction for prefission neutrons.

Monte Carlo analysis of HTTR with the MVP statistical geometry model

Mori, Takamasa; Okumura, Keisuke; Nagaya, Yasunobu; Ando, Hiroei

Transactions of the American Nuclear Society, 83, p.283 - 284, 2000/00

no abstracts in English

Statistics and predictions of population, energy and environment problems

Sobajima, Makoto

JAERI-Review 99-004, 64 Pages, 1999/03

JAERI-Review-99-004.pdf:3.05MB

no abstracts in English