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Journal Articles

Estimation of continuous distribution of iterated fission probability using an artificial neural network with Monte Carlo-based training data

Tuya, D.; Nagaya, Yasunobu

Journal of Nuclear Engineering (Internet), 4(4), p.691 - 710, 2023/11

The Monte Carlo method is used to accurately estimate various quantities such as k-eigenvalue and integral neutron flux. However, when a distribution of a quantity is desired, the Monte Carlo method does not typically provide continuous distribution. Recently, the functional expansion tally and kernel density estimation methods have been developed to provide continuous distribution. In this paper, we propose a method to estimate a continuous distribution of a quantity using artificial neural network (ANN) model with Monte Carlo-based training data. As a proof of concept, a continuous distribution of iterated fission probability (IFP) is estimated by ANN models in two systems. The IFP distributions by the ANN models were compared with the Monte Carlo-based data and the adjoint angular neutron fluxes by the PARTISN code. The comparisons showed varying degrees of agreement or discrepancy; however, it was observed that the ANN models learned the general trend of the IFP distributions.

Journal Articles

Insight on the mechanical properties of hierarchical porous calcium-silicate-hydrate pastes according to the Ca/Si molar ratio using ${it in situ}$ synchrotron X-ray scattering and nanoindentation test

Im, S.*; Jee, H.*; Suh, H.*; Kanematsu, Manabu*; Morooka, Satoshi; Choe, H.*; Nishio, Yuhei*; Machida, Akihiko*; Kim, J.*; Lim, S.*; et al.

Construction and Building Materials, 365, p.130034_1 - 130034_18, 2023/02

 Times Cited Count:17 Percentile:77.68(Construction & Building Technology)

Journal Articles

Evaluation of power distribution calculation of the very high temperature reactor critical assembly (VHTRC) with Monte Carlo MVP3 code

Simanullang, I. L.*; Nakagawa, Naoki*; Ho, H. Q.; Nagasumi, Satoru; Ishitsuka, Etsuo; Iigaki, Kazuhiko; Fujimoto, Nozomu*

Annals of Nuclear Energy, 177, p.109314_1 - 109314_8, 2022/11

 Times Cited Count:0 Percentile:0.00(Nuclear Science & Technology)

Journal Articles

An Investigation on the control rod homogenization method for next-generation fast reactor cores

Takino, Kazuo; Sugino, Kazuteru; Oki, Shigeo

Annals of Nuclear Energy, 162, p.108454_1 - 108454_7, 2021/11

 Times Cited Count:1 Percentile:9.64(Nuclear Science & Technology)

Journal Articles

Impact of PHITS spallation models on the neutronics design of an accelerator-driven system

Iwamoto, Hiroki; Nishihara, Kenji; Iwamoto, Yosuke; Hashimoto, Shintaro; Matsuda, Norihiro; Sato, Tatsuhiko; Harada, Masahide; Maekawa, Fujio

Journal of Nuclear Science and Technology, 53(10), p.1585 - 1594, 2016/10

 Times Cited Count:19 Percentile:83.51(Nuclear Science & Technology)

Journal Articles

Preliminary calculation with JENDL-4.0 for evaluation of dose rate distribution in the primary containment vessel of the Fukushima Daiichi Nuclear Power Station

Okumura, Keisuke

JAEA-Conf 2016-004, p.123 - 128, 2016/09

For the decommissioning of the Fukushima Daiichi Nuclear Power Station (1F), it is important to know the dose rate distribution in the primary containment vessel (PCV). However the distribution of radiation sources in PCV is not clear yet. There are three kinds of radiation sources in PCV. They are fuel debris, structures in PCV contaminated with Cs emitted at the 1F accident, and activated structures irradiated during normal reactor operating before the accident. In order to establish the evaluation method of the dose rate distribution in PCV, a preliminary calculation was carried out with JENDL-4.0. As a result, the sensitivity of each source to the dose distribution was obtained.

Journal Articles

Measurements and evaluations of air dose rates around Fukushima, 5; Characteristics of air dose rate distribution in the environment around the Fukushima Nuclear Power Plant site

Mikami, Satoshi; Matsuda, Norihiro; Ando, Masaki; Kinase, Sakae; Kitano, Mitsuaki; Kawase, Keiichi; Matsumoto, Shinichiro; Yamamoto, Hideaki; Saito, Kimiaki

Radioisotopes, 64(9), p.589 - 607, 2015/09

This article presents the features of regional distributions and temporal changes in air dose rate and radionuclide deposition densities in Fukushima on the basis of analyses on large-scale environmental monitoring results using diverse methods. The continuity of decontamination effects is discussed according to repeated monitoring data after the decontamination model project. Further, some examples are shown on the projection of air dose rates together with the ecological half lives for different land uses.

JAEA Reports

Development of denitration technique for MA-type bituminized waste product by aqueous leaching method

Irisawa, Keita; Komatsuzaki, Toshio; Kawato, Yoshimi; Sakakibara, Tetsuro; Nakazawa, Osamu; Meguro, Yoshihiro

JAEA-Technology 2015-008, 28 Pages, 2015/03

JAEA-Technology-2015-008.pdf:13.63MB

In JAEA, 16,671 drums of intermediate-radioactive bituminized waste products (BWPs) have been stored in asphalt solidification storages. As a way of reduction of uncertainty in assessment of disposal of the BWPs, a processing technique of separation of nitrate salts from the BWP by means of an aqueous leaching method was studied. As elemental techniques for the denitration process, (1) crushing techniques of a BWP and (2) denitration techniques for the crushed BWP by the aqueous leaching method were investigated. In order to promote leaching amounts of nitrates, the BWP was crushed, and the grain size distribution was investigated by sieving. Moreover, leaching behaviors of nitrate, nitrite and elements as radionuclides including in the BWP were investigated.

Journal Articles

Neutronic performance of rectangular and cylindrical coupled hydrogen moderators in wide-angle beam extraction of low-energy neutrons

Kai, Tetsuya; Harada, Masahide; Teshigawara, Makoto; Watanabe, Noboru; Kiyanagi, Yoshiaki*; Ikeda, Yujiro

Nuclear Instruments and Methods in Physics Research A, 550(1-2), p.329 - 342, 2005/09

 Times Cited Count:19 Percentile:75.18(Instruments & Instrumentation)

Neutronic study was performed on coupled hydrogen moderators to maximize time-integrated and pulse-peak intensities of slow neutrons when a large number of beams was required. The total increased with the number of beams, although the average decreased due to a reflector-missing by the beam extraction holes in the reflector. At a large beam extraction angle (25 degree), the spatial distribution of the vector-flux of neutrons was undesirable for a rectangular shape moderator. As an alternative we proposed a cylindrical shape one, resulting in a much improved spatial distribution. In addition, neutronic performance was calculated as a function of the diameter, indicating the optimal diameter was about 140 mm. The cylindrical one gave higher pulse-peak intensities with narrower pulse widths without penalty in time-integrated intensities and pulse decay characteristics, providing a more uniform angle-dependence. Some explanations are given for the difference in the pulse characteristics between the two. We decided to adopt the cylindrical one for the Japanese spallation neutron source.

Journal Articles

Migration mechanisms of $$^{237}$$Np and $$^{241}$$Am through loess media

Tanaka, Tadao; Mukai, Masayuki; Maeda, Toshikatsu; Matsumoto, Junko; Ogawa, Hiromichi; Li, Z.*; Wang, X.*; Fan, Z.*; Guo, L.*; Liu, C.*

Journal of Radioanalytical and Nuclear Chemistry, 256(2), p.205 - 211, 2003/05

 Times Cited Count:3 Percentile:25.19(Chemistry, Analytical)

Migration experiments of $$^{237}$$Np(V) and $$^{241}$$Am(III) have been performed using a column system, to investigate migration behavior of Np and Am through a column packed with loess, taken from Shanxi, China. Adsorption mechanisms of Np and Am on the loess were examined by a chemical extraction method. In the case of the Np, most of Np adsorbed on the influent edge of the column. The Np adsorbed on the loess was mainly controlled by surface complexation. However, the migration of Np in the loess media could be roughly evaluated by using the distribution coefficient. In the case of the Am, particulate Am species was formed in the influent solution and moved in the column. The Am adsorbed on the loess was controlled by irreversible reactions. The migration behavior of particulate Am in the loess media could be expressed by the filtration theory.

JAEA Reports

Dose equivalent rate and radiation monitoring results during power distribution measurements of HTTR

Takada, Eiji*; Fujimoto, Nozomu; Nojiri, Naoki; Umeta, Masayuki; Kokusen, Shigeru; Ashikagaya, Yoshinobu

JAERI-Data/Code 2002-009, 83 Pages, 2002/05

JAERI-Data-Code-2002-009.pdf:3.51MB

Dose equivalent rate around the fuel handling machine, the control rod handling machine, stand pipe compartment, maintenance pit were measured during gamma ray measurements from HTTR fuel, which was called as “power distribution measurements". The power distribution measurement was the first time to handle the fuel blocks irradiated in the core. Dose equivalent rate measurement aiming the check of shielding performance of components, the check of unexpected streaming path. The radiation monitoring during operation was carried out. As the results, there was no problem on shielding. The measured data at operation condition were also obtained. The data will be useful to expect operation circumstance in the future.

Journal Articles

Relationships between dose rates measured 1m above ground level and the $$^{137}$$Cs depth distribution in the Chernobyl grounds

Sakamoto, Ryuichi; Saito, Kimiaki; Tsutsumi, Masahiro; Nagaoka, Toshi; Stolyarevsky, I.*; Glebkin, S.*; Tepikin, V.*; Arkhipov, N.*; Ramzaev, V.*; Mishine, A.*; et al.

Proceedings of 10th International Congress of the International Radiation Protection Association (IRPA-10) (CD-ROM), 5 Pages, 2000/05

no abstracts in English

Journal Articles

Measurement of induced radioactivity in copper exposed to high energy heavy ion beam

Kim, E.; Nakamura, Takashi*; Uwamino, Y.*; Ito, S.*; Fukumura, A.*

Journal of Nuclear Science and Technology, 37(Suppl.1), p.811 - 815, 2000/03

no abstracts in English

Journal Articles

Benchmark analysis of experiments in fast critical assemblies using a continuous-energy monte carlo code MVP

Nagaya, Yasunobu; Nakagawa, Masayuki; Mori, Takamasa

Journal of Nuclear Science and Technology, 35(1), p.6 - 19, 1998/01

 Times Cited Count:4 Percentile:31.90(Nuclear Science & Technology)

no abstracts in English

Journal Articles

Measurement of flux tilt and eigenvalue separation in axially decoupled core

Ando, Masaki; ; Nishina, Kojiro*;

Journal of Nuclear Science and Technology, 34(5), p.445 - 453, 1997/05

 Times Cited Count:6 Percentile:47.33(Nuclear Science & Technology)

no abstracts in English

Journal Articles

Statistical analysis of fallout radionuclides transfer to paddy-field rice

Takahashi, Tomoyuki; ;

Int. Conf. on Deep Geological Disposal of Radioactive Waste,Conf. Proc., 0, p.4.107 - 4.116, 1996/00

no abstracts in English

Journal Articles

Measurements and analyses of the ratio of $$^{238}$$U captures to $$^{235}$$U fission in low-enriched UO$$_{2}$$ tight lattices

Nakajima, Ken; ; Yamamoto, Toshihiro; ; Suzaki, Takenori

Journal of Nuclear Science and Technology, 31(11), p.1160 - 1170, 1994/11

 Times Cited Count:7 Percentile:56.04(Nuclear Science & Technology)

no abstracts in English

Journal Articles

Study on streaming neutron effect through calculation for reaction rate distribution with gold wire at the KUCA

Ando, Masaki; ;

Annual Reports of the Research Reactor Institute, Kyoto University, 26, p.118 - 124, 1993/00

no abstracts in English

Journal Articles

Experimental studies on thermal and hydraulic performance of fuel stack of VHTR, VI; Results of crossflow test by HENDEL multi-channel test rig

Takase, Kazuyuki; Hino, Ryutaro;

Nihon Genshiryoku Gakkai-Shi, 33(6), p.564 - 573, 1991/06

 Times Cited Count:0 Percentile:0.00(Nuclear Science & Technology)

no abstracts in English

36 (Records 1-20 displayed on this page)