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Journal Articles

A Functional expansion tally method with numerical basis sets generated by singular value decomposition for one-dimensional Monte Carlo calculations

Kondo, Ryoichi; Nagaya, Yasunobu

Proceedings of International Conference on Mathematics and Computational Methods Applied to Nuclear Science and Engineering (M&C 2023) (Internet), 10 Pages, 2023/08

A functional expansion tally (FET) method with numerical basis functions generated by singular value decomposition (SVD) is newly proposed. Traditionally, analytical functions were used for the FET calculations, e.g., Legendre polynomials for a one-dimensional distribution. However, the expansion terms could increase to reconstruct steep or complex distributions with these functions. A basis set that can well represent the target distribution with lower order expansion is desired to achieve high accuracy with the small computational resource. In the present study, a numerical basis set is generated from snapshot data by using SVD. This approach is based on the reduced order modeling (ROM). We applied ROM to the FET method in Monte Carlo calculations. The numerical result showed the applicability of the proposed method, on the other hand, some issues were revealed, e.g., discretization of the snapshot data.

Journal Articles

Development of ACE file perturbation tool using FRENDY

Tada, Kenichi; Kondo, Ryoichi; Endo, Tomohiro*; Yamamoto, Akio*

Journal of Nuclear Science and Technology, 60(6), p.624 - 631, 2023/06

 Times Cited Count:1 Percentile:56.43(Nuclear Science & Technology)

The sensitivity analysis and the uncertainty quantification have an important role in improving the evaluated nuclear data library. The current computational performance enables us to the sensitivity analysis and uncertainty quantification using the continuous energy Monte Carlo calculation code. The ACE file perturbation tool was developed for these calculations using modules of FRENDY. This tool perturbs the microscopic cross section, the number of neutrons per fission, and the fission spectrum. The uncertainty quantification using the random sampling method is also available if the user prepares the covariance matrix. The uncertainty of the k-effective using the perturbation tool was compared to the current sensitivity analysis codes SCALE/TSUNAMI and MCNP/KSEN. The comparison results indicated that the random sampling method using this tool accurately estimates the uncertainty of k-effective.

Journal Articles

Study on resonance calculation using energy spectrum expansion method

Kondo, Ryoichi

Robutsuri No Kenkyu (Internet), (75), 3 Pages, 2023/03

The author received the encouragement award from the reactor physics division of the atomic energy society of Japan. The research on the RSE (Resonance calculation using energy Spectrum Expansion) method, which is the subject of the award, is described for the bulletin of the reactor physics division.

Journal Articles

Development of nuclear data processing code FRENDY version 2

Tada, Kenichi; Yamamoto, Akio*; Kunieda, Satoshi; Konno, Chikara; Kondo, Ryoichi; Endo, Tomohiro*; Chiba, Go*; Ono, Michitaka*; Tojo, Masayuki*

Journal of Nuclear Science and Technology, 10 Pages, 2023/00

Nuclear data processing code is important to connect evaluated nuclear data libraries and radiation transport codes. The nuclear data processing code FRENDY version 1 was released in 2019 to generate ACE formatted cross section files with simple input data. After we released FRENDY version 1, many functions were developed, e.g., neutron multi-group cross section generation, explicit consideration of the resonance interference effect among different nuclides in a material, consideration of the resonance upscattering, ACE file perturbation, and modification of ENDF-6 formatted file. FRENDY version 2 was released including these new functions. It generates GENDF and MATXS formatted neutron multi-group cross section files from an ACE formatted cross section file or an evaluated nuclear data file. This paper explains the features of the new functions implemented in FRENDY version 2 and the verification of the neutron multigroup cross section generation function of this code.

Journal Articles

Implementation of random sampling for ACE-format cross sections using FRENDY and application to uncertainty reduction

Kondo, Ryoichi*; Endo, Tomohiro*; Yamamoto, Akio*; Tada, Kenichi

Proceedings of International Conference on Mathematics and Computational Methods applied to Nuclear Science and Engineering (M&C 2019) (CD-ROM), p.1493 - 1502, 2019/00

A perturbation capability of ACE formatted cross section files was developed using the modules of FRENDY. Uncertainty quantification using MCNP was carried out for the Godiva critical experiment by the RS method. We verified the results of the RS method by comparing with those obtained by the conventional sensitivity analyses. Moreover, uncertainty reduction using the bias factor method with the RS technique was applied to kinetic parameter, i.e., neutron generation time.

Journal Articles

Development of a sub-MeV X-ray source via Compton backscattering

Kawase, Keigo; Kando, Masaki; Hayakawa, Takehito; Daito, Izuru; Kondo, Shuji; Homma, Takayuki; Kameshima, Takashi*; Kotaki, Hideyuki; Chen, L. M.*; Fukuda, Yuji; et al.

Nuclear Instruments and Methods in Physics Research A, 637(1, Suppl.), p.S141 - S144, 2011/05

 Times Cited Count:7 Percentile:49.05(Instruments & Instrumentation)

We report the present status of the sub-MeV X-ray generation via Compton backscattering by using 150-MeV electron beam and the Nd:YAG laser. In particular, we show the result of the X-ray generation experiment and of the laser pulse compression for increasing the X-ray flux.

Journal Articles

Improvement of SBS laser pulse compression system for the Compton backscattered X-ray source

Kawase, Keigo; Kando, Masaki; Hayakawa, Takehito; Daito, Izuru; Kondo, Shuji; Homma, Takayuki; Kameshima, Takashi*; Kotaki, Hideyuki; Chen, L. M.*; Fukuda, Yuji; et al.

JAEA-Conf 2010-002, p.95 - 98, 2010/06

At the previous symposium in Advanced Photon Research, we proposed and demonstrated the laser pulse compression via stimulated Brillouin scattering (SBS) for increasing the flux of the Compton backscattered X rays. After that, we improved the SBS pulse compression system by introducing the image relay in the laser transport line. As a result, we achieve the stably compressed laser pulse with a duration of 2.1 ns and with an energy of 0.84 J. By installing this system into the Compton backscattered X-ray source, the X-ray flux will be increased 3.2 times for the present system at the KPSI-JAEA.

JAEA Reports

Supplement to radiation shielding analysis of JOYO (C)

Kondo, Ryoichi*; Ozawa, Takeshi*; Horie, Junnosuke*; Handa, Hiroyuki*

PNC TJ202 82-03, 76 Pages, 1982/02

PNC-TJ202-82-03.pdf:1.43MB

A supplemental study on the JOYO's shielding analysis was performed focussing attention on the behavior of neutron and $$gamma$$-ray fluxes around the detector guide tube of channel a and on the evaluation of the primary sodium activation with use made of the two-dimensional discrete ordinates transport code. It has been found out that secondary $$gamma$$ rays emitted from a thin guide tube material of SS-304 has a strong effect of enhancing gamma doserates in the guide tube penetrating through a graphite shielding. The effect of the guide tube penetrating a heavy concrete pedestal has been revealed to be a streaming of neutrons and gammas. It can be concluded that the effect of the detector guide tube on the neutron and $$gamma$$ ray should be taken into account when comparing the calculated values with experimental values. The neutron flux distribution in the full reactor lower axial two dimensional geometry has been calculated and used, together with the results obtained by the upper axial two dimensional a

Oral presentation

Nondestructive assay of Pu, U and MA's in spent fuel by usinga mono-energetic $$gamma$$-ray beam, 1; Facility design and R&D status

Hajima, Ryoichi; Hayakawa, Takehito; Kikuzawa, Nobuhiro; Shizuma, Toshiyuki; Nishimori, Nobuyuki; Nagai, Ryoji; Sawamura, Masaru; Kawase, Keigo; Kosuge, Atsushi; Tateno, Ryo; et al.

no journal, , 

no abstracts in English

Oral presentation

40 MeV proton beam Generation with ultra-high intensity high-contrast Ti:Sapphire laser system, 2

Ogura, Koichi; Nishiuchi, Mamiko; Pirozhkov, A. S.; Tanimoto, Tsuyoshi; Sagisaka, Akito; Esirkepov, T. Z.; Shizuma, Toshiyuki; Hayakawa, Takehito; Hajima, Ryoichi; Kando, Masaki; et al.

no journal, , 

We demonstrated the energetic proton generation using 40 fsec intense Ti:Sapphire laser pulses. By drastically increasing the interaction intensity approximately 1E21 W/cm$$^{2}$$ with keeping a ultra high contrast of 1E10:1, even without using plasma mirror, over 40 MeV protons were detected with 800 nm thick Al foil.

Oral presentation

Effect of focused ion beam processing on stainless steel studied by positron annihilation lifetime measurements

Minei, Shuntaro; Oshima, Nagayasu*; Sakai, Hiroaki; Okubo, Nariaki; Kondo, Keietsu; Suzuki, Ryoichi*; Hirade, Tetsuya

no journal, , 

In nuclear reactor materials, subnanometer-size vacancy type defects are induced by neutron irradiation. Although positron annihilation methods are effective techniques for evaluation of the vacancy type defects, it may be difficult to apply the methods for neutron irradiated samples, because of $$gamma$$-rays from highly neutron irradiated, i.e. radioactivated, samples. Recently, positron micro beam has been developed at AIST. Therefore, we are suggesting that smaller radioactivated samples emit fewer $$gamma$$-rays. Focused Ion beam (FIB) is one of the tools to prepare micrometer scale samples by ion sputtering, for example, for the transmission electron microscope. There is some possibility to have vacancy type defects in the samples induced by the FIB processing and it can make estimation of the pre-existing defects in the samples difficult. The results investigated by positron annihilation lifetime measurements for SUS316L showed that FIB can be applied.

Oral presentation

Development of 100W class Yb-fiber laser system for the isotope-specific non-destructive assay by using intense laser-Compton $$gamma$$-rays

Mori, Michiaki; Kosuge, Atsushi*; Hajima, Ryoichi; Nagashima, Keisuke; Kondo, Kiminori; Kiriyama, Hiromitsu

no journal, , 

We report on a high average power Yb-fiber CPA laser system. The system can produces an average power of 100 W class at 160 MHz in a $$sim$$5 ps pulse with narrow bandwidth of $$sim$$ 0.4 nm in full-width-half-maximum. The bandwidth of the laser beam can be varied (from 0.4 nm to 2 nm) easily by changing the configuration of a spectrum mask at a secondary pulse stretcher. The power fluctuation is only 0.6% (rms value), which was measured over a period of 10 hours. The excellent beam profile is preserved over the full range of average power. The reliable, efficient, and compact our fiber laser system is currently being applied to realize intense LCS $$gamma$$-ray source.

Oral presentation

Implementation of random sampling for ACE-format cross sections using FRENDY

Kondo, Ryoichi*; Endo, Tomohiro*; Yamamoto, Akio*; Tada, Kenichi

no journal, , 

The random sampling module for ACE format cross sections are developed using modules of FRENDY. This module perturbs the cross sections and other parameters in ACE format cross section library using covariance data. The GODIVA reactor is used and the calculation results of TSUNAMI-1D are compared to verify this module.

Oral presentation

Development of the functional expansion tally method expanded by numerical basis functions extracted by singular value decomposition, 1; Verification for one-dimensional geometry

Kondo, Ryoichi; Nagaya, Yasunobu

no journal, , 

A functional expansion tally (FET) method expanded by numerical basis functions has been developed for Monte Carlo transport simulation. The numerical basis functions were extracted from various flux distributions by singular value decomposition, to expand the target flux distribution with low order bases. In this work, multi-group Monte Carlo calculations were carried out for one-dimensional geometry. The accuracy of the spatial flux distributions obtained by the proposed method was confirmed in comparison with the traditional discrete cell tally method and the FET method expanded by Legendre polynomials.

Oral presentation

Development of the functional expansion tally method expanded by numerical basis functions extracted by singular value decomposition, 2; Application to one-dimensional whole core geometry

Kondo, Ryoichi; Nagaya, Yasunobu

no journal, , 

A functional expansion tally (FET) method expanded by numerical basis functions is under development for Monte Carlo transport simulation. In this work, a multi-group Monte Carlo calculation was performed to obtain the flux distribution with the FET method using numerical basis functions for one-dimensional whole core geometry. The numerical basis functions were generated by singular value decomposition of fluxes, which were calculated by a deterministic method in unit assembly with various calculation conditions. The whole core flux distribution was calculated by expanding the flux distribution of each assembly with the numerical basis functions. The accuracy of the proposed method was confirmed in comparison with the discrete tally method and the conventional Legendre polynomials based FET method.

Oral presentation

Development of multi-physics platform JAMPAN

Tada, Kenichi; Kondo, Ryoichi; Kamiya, Tomohiro; Nagatake, Taku; Ono, Ayako; Nagaya, Yasunobu; Yoshida, Hiroyuki

no journal, , 

JAEA has developed a Python-based multi-physics platform JAMPAN. This platform has an HDF5 formatted JAMPAN data container. It connects calculation codes via this data container. The utilization of this container eliminates the dependence on the calculation code and enables us to easily exchange the coupling code. The first target of JAMPAN is a coupling of neutronics and thermal hydraulics codes to provide reference results of core analysis codes. The coupling of the other codes such as a fuel performance analysis code FEMAXI is future work. This presentation shows the overview of the JAMPAN platform.

Oral presentation

Boiling simulation in 8$$times$$8 single bundle assembly of BWR

Kamiya, Tomohiro; Ono, Ayako; Nagatake, Taku; Tada, Kenichi; Kondo, Ryoichi; Nagaya, Yasunobu; Yoshida, Hiroyuki

no journal, , 

JAEA aims to obtain reference solutions for reactor design codes by coupling the Monte Carlo code MVP and the multiphase and multi-component detailed thermal-hydraulic analysis code JUPITER on the multiphysics platform JAMPAN (JAEA Advanced Multi-Physics Analysis platform for Nuclear systems). For BWR, the thermal-hydraulic analysis code is required to consider boiling around fuel rods. Therefore, a thermal-hydraulic simulation of an 8$$times$$8 STEP-II single fuel assembly system was performed considering boiling using the temperature recovery method.

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