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Journal Articles

Application of polynomial chaos expansion technique to dynamic probabilistic risk assessment of nuclear power plants

Kubo, Kotaro; Tanaka, Yoichi

Proceedings of Asian Symposium on Risk Assessment and Management 2021 (ASRAM 2021) (Internet), 13 Pages, 2021/10

Probabilistic risk assessment (PRA) is extensively used, e.g., in periodical safety review and the reactor oversight process, in nuclear regulation systems to improve the safety of nuclear power plants; however, one limitation of classical PRA is the handling of temporal information such as system failure and core damage timings. To resolve this limitation, the dynamic PRA method has been developed and applied for multiple safety issues; however, its improvement is accompanied by considerable computational costs. In this study, we applied the polynomial chaos expansion (PCE) technique to dynamic PRA with the expectation of reduction in computational cost. In particular, to estimate core damage timing, a PCE-based surrogate model was developed. Then, the surrogate model was applied to dynamic PRA to calculate the conditional core damage probability and core damage timing. Consequently, applying the PCE might efficiently perform these analyses without considerable reduction in accuracy.

Journal Articles

Anisotropic thermal lattice expansion and crystallographic structure of strontium aluminide within Al-10Sr alloy as measured by in-situ neutron diffraction

Liss, K.-D.*; Harjo, S.; Kawasaki, Takuro; Aizawa, Kazuya; Xu, P. G.

Journal of Alloys and Compounds, 869, p.159232_1 - 159232_9, 2021/07

 Times Cited Count:0 Percentile:0(Chemistry, Physical)

Journal Articles

Experimental investigation of the glass transition of polystyrene thin films in a broad frequency range

Inoue, Rintaro*; Kanaya, Toshiji*; Yamada, Takeshi*; Shibata, Kaoru; Fukao, Koji*

Physical Review E, 97(1), p.012501_1 - 012501_6, 2018/01

 Times Cited Count:8 Percentile:75.32(Physics, Fluids & Plasmas)

In this study, we investigate the $$alpha$$ process of a polystyrene thin film using inelastic neutron scattering (INS), dielectric relaxation spectroscopy (DRS), and thermal expansion spectroscopy (TES). The DRS and TES measurements exhibited a decrease in glass transition temperature ($$T_{rm g}$$) with film thickness. On the other hand, an increase in $$T_{rm g}$$ was observed in INS studies. In order to interpret this contradiction, we investigated the temperature dependence of the peak frequency ($$f_{rm m}$$) of the $$alpha$$ process probed by DRS and TES. The experiments revealed an increase in the peak frequency ($$f_{rm m}$$) with decreasing film thickness in the frequency region. This observation is consistent with the observed decrease in $$T_{rm g}$$ with thickness. The discrepancy between INS and DRS or TES descriptions of the $$alpha$$ process is likely to be attributed to a decrease in the apparent activation energy with film thickness and reduced mobility, due to the impenetrable wall effect.

JAEA Reports

An Irradiation test of heat-resistant ceramic composite materials, 2; Interim report on post-irradiation examinations of the second and third preliminary test, 98M-41A, 99M-30A

Baba, Shinichi; Nemoto, Makoto*; Sozawa, Shizuo; Yamaji, Masatoshi*; Ishihara, Masahiro; Sawa, Kazuhiro

JAERI-Tech 2005-055, 157 Pages, 2005/09

JAERI-Tech-2005-055.pdf:19.06MB

The Japan Atomic Energy Research Institute (JAERI) has been carrying out the research on radiation damage mechanism of heat-resistant ceramics composite materials, as one of the subjects of the innovative basic research on high temperature engineering using the High Temperature Engineering Test Reactor (HTTR). A series of preliminary irradiation tests is being made using the Japan Materials Testing Reactor (JMTR). The present report describes results of post-irradiation examinations so far on specimens irradiated in the second and third capsule, designated 98M-41A and 99M-30A, to fast neutron fluences of 1.0$$times$$10$$^{25}$$m$$^{-2}$$(E$$>$$1MeV) at temperatures of 973K-1173K and 1273K-1473K. The PIE were conducted as the fundamental statistics index of the diametral dimensions for irradiated specimen, irradiation induced dimensional change rate and thermal expansion rate.

Journal Articles

Phase equilibria and thermal expansion of CaTiO$$_{3}$$ doped with neptunium

Sato, Tsuyoshi*; Yamashita, Toshiyuki; Matsui, Tsuneo*

Journal of Nuclear Materials, 344(1-3), p.67 - 72, 2005/09

 Times Cited Count:2 Percentile:18.81(Materials Science, Multidisciplinary)

Phase relationships between NpO$$_{2}$$ and CaTiO$$_{3}$$ or Ca(Ti, Al)O$$_{3}$$ were investigated by X-ray diffraction (XRD) analysis, using specimens prepared at 1773 K in Ar-8%H$$_{2}$$. Single phase solid solutions were formed 0-7.5 mol%Np and 1-10 mol%Np for CaTiO$$_{3}$$ and Ca(Ti, Al)O$$_{3}$$, respectively. By substituting Al for Ti in CaTiO$$_{3}$$, Np solubility in Ca(Ti, Al)O$$_{3}$$ increased. Solubility of Np was compared with those of U and Pu, and was discussed with oxidation states and ionic radii of dopants. Thermal expansions of (Ca,Np)TiO$$_{3}$$ were measured from room temperature to 1273 K in Ar-8%H$$_{2}$$ using high-temperature XRD technique. These specimens showed nearly the same value of volumetric thermal expansion coefficients, suggesting that the incorporation of tetravalent Np into CaTiO$$_{3}$$ had practically no effect on stabilization of the crystal lattice. This finding was in a marked contrast to that of Pu doped CaTiO$$_{3}$$, where pronounced stabilization in the crystal was observed by incorporating Pu into CaTiO$$_{3}$$.

JAEA Reports

Data on post irradiation experiments of heat resistant ceramic composite materials; PIE for 97M-13A

Baba, Shinichi; Ishihara, Masahiro; Sozawa, Shizuo; Sekino, Hajime

JAERI-Data/Code 2003-003, 394 Pages, 2003/03

JAERI-Data-Code-2003-003.pdf:13.63MB

The research on the radiation damage mechanism of heat resistant ceramic composite materials is one of the research subjects of the innovative basic research in the field of high temperature engineering, using the High Temperature engineering Test Reactor (HTTR). Three series of irradiation tests on the heat resistant ceramic composite materials, first to third irradiation test program, were carried out using the Japan Material Testing Reactor (JMTR). This is a summary report on the the first irradiation test program; irradiation induced dimensional change, thermal expansion coefficient, X-ray diffraction and $$gamma$$-ray spectrum are reported.

Journal Articles

Irradiation effects on thermal expansion of SiC/SiC composite materials

Ishihara, Masahiro; Baba, Shinichi; Hoshiya, Taiji; Shikama, Tatsuo*

Journal of Nuclear Materials, 307-311(Part2), p.1168 - 1172, 2002/12

 Times Cited Count:5 Percentile:35.97(Materials Science, Multidisciplinary)

no abstracts in English

JAEA Reports

Analysis of the applicability of acceleration methods for a triangular prism geometry nodal diffusion code

Fujimura, Toichiro*; Okumura, Keisuke

JAERI-Research 2002-024, 27 Pages, 2002/11

JAERI-Research-2002-024.pdf:1.04MB

A prototype version of a diffusion code has been developed to analyze the hexagonal core as reduced moderation reactor and the applicability of some acceleration methods have been investigated to accelerate the convergence of the iterative solution method. The hexagonal core is divided into regular triangular prisms in the three-dimensional code MOSRA-Prism and a polynomial expansion nodal method is applied to approximate the neutron flux distribution by a cubic polynomial. The multi-group diffusion equation is solved iteratively with ordinal inner and outer iterations and the effectiveness of acceleration methods is ascertained by applying an adaptive acceleration method and a neutron source extrapolation method, respectively. The formulation of the polynomial expansion nodal method is outlined in the report and the local and global effectiveness of the acceleration methods is discussed with various sample calculations. A new general expression of vacuum boundary condition, derived in the formulation is also described.

Journal Articles

Lattice parameter expansion by self-irradiation damage of $$^{244}$$Cm-$$^{240}$$Pu oxide and mononitride

Takano, Masahide; Ito, Akinori; Akabori, Mitsuo; Ogawa, Toru; Numata, Masami; Kizaki, Minoru

Journal of Nuclear Science and Technology, 39(Suppl.3), p.842 - 845, 2002/11

no abstracts in English

JAEA Reports

Temperature dependence of lattice vibrations and analysis of specific heat in graphite (Cooperative research)

Nihira, Takeshi*; Iwata, Tadao*; Iwase, Akihiro

JAERI-Research 2001-045, 33 Pages, 2001/11

JAERI-Research-2001-045.pdf:1.27MB

no abstracts in English

JAEA Reports

A Study on density, melting point, thermal expansion, creep, thermal diffusivity and thermal conductivity of the simulated rock-like oxide (ROX) fuels

Yanagisawa, Kazuaki; Omichi, Toshihiko*; Shirasu, Noriko; Muromura, Tadasumi; *

JAERI-Tech 99-032, 65 Pages, 1999/03

JAERI-Tech-99-032.pdf:3.23MB

no abstracts in English

JAEA Reports

MOSRA-Light; High speed three-dimensional nodal diffusion code for vector computers

Okumura, Keisuke

JAERI-Data/Code 98-025, 243 Pages, 1998/10

JAERI-Data-Code-98-025.pdf:10.15MB

no abstracts in English

Journal Articles

Thermal expansion and thermal conductivity of cesium uranates

Takano, Masahide; Minato, Kazuo; Fukuda, Kosaku; Sato, Seichi*; Ohashi, Hiroshi*

Journal of Nuclear Science and Technology, 35(7), p.485 - 493, 1998/07

 Times Cited Count:4 Percentile:39.76(Nuclear Science & Technology)

no abstracts in English

Journal Articles

Thermal expansion and thermal conductivity of Cs$$_{2}$$CrO$$_{4}$$

Takano, Masahide; Minato, Kazuo; Fukuda, Kosaku; Sato, Seichi*; Ohashi, Hiroshi*

Journal of Alloys and Compounds, 278, p.277 - 282, 1998/00

 Times Cited Count:1 Percentile:20.14(Chemistry, Physical)

no abstracts in English

Journal Articles

Thermal expansion and thermal conductivity of cesium molybdate

Minato, Kazuo; Takano, Masahide; Fukuda, Kosaku; Sato, Seichi*; Ohashi, Hiroshi*

Journal of Alloys and Compounds, 255, p.18 - 23, 1997/00

 Times Cited Count:14 Percentile:66.52(Chemistry, Physical)

no abstracts in English

Journal Articles

Electron spectra from doublet and quartet states of N$$^{4+}$$(1s3l3l') produced by 60keV N$$^{6+}$$+H$$_{2}$$,O$$_{2}$$ collisions

*; Awaya, Yoko*; F.J.Currell*; Kambara, Tadashi*; Kanai, Yasuyuki*; Kitazawa, Shinichi; *; *; U.I.Safronova*; *; et al.

Journal of Physics B; Atomic, Molecular and Optical Physics, 29, p.1995 - 2006, 1996/00

 Times Cited Count:5 Percentile:37.13(Optics)

no abstracts in English

Journal Articles

Thermal properties of cesium molybdate

Minato, Kazuo; Takano, Masahide*; Sato, Seichi*; Ohashi, Hiroshi*; Fukuda, Kosaku

Transactions of the American Nuclear Society, 74, p.95 - 96, 1996/00

no abstracts in English

Journal Articles

Effect of selection of calculation parameters in discrete ordinate code DOT3.5 for analyses of fusion blanket integral experiments in JAERI-USDOE collaborative program

Oyama, Yukio; Kosako, Kazuaki*; Konno, Chikara; Ikeda, Yujiro; Maekawa, Fujio; Maekawa, Hiroshi

Fusion Engineering and Design, 28, p.636 - 641, 1995/00

no abstracts in English

Journal Articles

Metastable states population densities in Gd atomic beam at high-rate evaporation by electron beam heating

Nishimura, Akihiko; Arisawa, Takashi; Oba, Hironori; Shibata, Takemasa

J. Vac. Sci. Technol., A, 11(4), p.1516 - 1521, 1993/07

no abstracts in English

Journal Articles

Angular distribution of gadolinium vapor produced by electron beam heating

Nishimura, Akihiko; ; Oba, Hironori; Shibata, Takemasa

Journal of Nuclear Science and Technology, 30(3), p.270 - 273, 1993/03

 Times Cited Count:12 Percentile:83.82(Nuclear Science & Technology)

no abstracts in English

38 (Records 1-20 displayed on this page)