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Maruyama, Shuhei; Yamamoto, Akio*; Endo, Tomohiro*
Annals of Nuclear Energy, 205, p.110591_1 - 110591_13, 2024/09
Endo, Tomohiro*; Maruyama, Shuhei; Yamamoto, Akio*
Journal of Nuclear Science and Technology, 61(3), p.363 - 374, 2024/03
Times Cited Count：0 Percentile：0.01(Nuclear Science & Technology)Uncertainty quantification (UQ) of the neutron multiplication factor is important to investigate the appropriate safety margin for a target system. Although the random sampling method is a practical and useful UQ method, a large computational cost is required to reduce the statistical error of the estimated uncertainty. Furthermore, if an input variable follows a normal distribution with a large standard deviation, the perturbed input variable by the random sampling method may become a physically inappropriate or negative value. To address these issues for the efficient and robust UQ, a modified deterministic sampling method using the simplex ensemble and the scaling method is proposed. The features of the proposed method are summarized as follows: The sample size is (r+2), where r corresponds to the effective rank of the covariance matrix between the input variables; depending on a situation of target UQ, the amounts of perturbations for the input parameters can be arbitrarily given by the scaling factor method; the scaling factor can be updated to avoid physically inappropriate in the perturbed input variables. The effectiveness of the proposed method is demonstrated through the UQ of the neutron multiplication factor due to fuel manufacturing uncertainties for a typical PWR pin-cell burnup calculation.
Maruyama, Shuhei; Endo, Tomohiro*; Yamamoto, Akio*
Journal of Nuclear Science and Technology, 61(1), p.31 - 43, 2024/01
Times Cited Count：0 Percentile：0.01(Nuclear Science & Technology)This study investigated the feasibility of reducing the uncertainty associated with fast-reactor-core design by sharing an experimental database between different fields (e.g., reactor physics and radiation shielding) using data assimilation techniques. As the first step in this study, we focused on the ORNL sodium shielding experiment and investigated the possibility of using the experimental data to reduce the uncertainty in sodium void reactivity (SVR), which is the most important safety parameter for sodium-cooled fast reactors. A sensitivity analysis based on the Generalized Perturbation Theory was performed for the sodium shielding experiment. Using the sensitivity coefficients evaluated here and those of the sodium void reactivity previously evaluated by the JAEA, we showed that sodium shielding experimental data can contribute to the uncertainty reduction of SVR by adopting the cross-section adjustment method. Based on this study, the uncertainty reduction effect is expected to be significant, especially for SVR dominated by neutron-leakage phenomena. Although new reactor physics experimental data on SVR may be difficult to obtain, the results of this study suggest that data from sodium shielding experiments can partially substitute for this role. This study demonstrated the value of the mutual use of integral experimental data in fast reactor designs.
Maruyama, Shuhei; Endo, Tomohiro*; Yamamoto, Akio*
Journal of Nuclear Science and Technology, 60(11), p.1372 - 1385, 2023/11
Times Cited Count：1 Percentile：68.31(Nuclear Science & Technology)Nakamura, Takafumi*; Yamamoto, Yukio*; Arakawa, Masakazu*; Maruyama, Akio*; Yoshigoe, Akitaka
Sangyo Oyo Kogakukai Rombunshi, 11(2), p.109 - 114, 2023/09
Surface chemistry experimental end-station at BL23SU in SPring-8 is widely used to study various surfaces and interfaces of functional materials by means of soft X-rays synchrotron radiation. To analyze surface chemical reactions between gas and solid surfaces, an accurate control of flow-rates of gases is essential. This paper describes a computerized automatic gas flow control system to improve the accuracy and reproducibility of gas-surface reaction experiments in the pressure range of ultra-high vacuum (molecular flow) conditions. The system uses feedback control to operate the slow-leak valve to control the gas-pressure. As a result, the system achieved results equivalent to those of a skilled experimenter.
Maruyama, Shuhei; Endo, Tomohiro*; Yamamoto, Akio*
EPJ Web of Conferences, 281, p.00008_1 - 00008_9, 2023/03
The applicability of Akaike's Bayesian Information Criterion (ABIC) to covariance modeling in the cross-section adjustment method was investigated. One of the most important things for a reliable cross-section adjustment method is giving a suitable covariance matrix. However, since we cannot know the true covariance matrix in advance, we usually estimate and assume it. To judge the goodness of the covariance matrix modeling, a metric is desirable. As a candidate for this metric, we focus on ABIC which is one of the information criteria in Bayesian inference, because the cross-section adjustment method is often discussed within the framework of Bayesian inference. In the conventional cross-section adjustment method, incorporation of the analysis model uncertainty in a covariance matrix still requires ad hoc treatment. In JAEA, the integral experimental database for fast reactors has been developed and the adjusted cross-section set ADJ2017 has been created based on this database. Many of the core characteristics in the database have been analyzed by a deterministic method. Therefore, the predicted core characteristics have non-negligible uncertainties with correlations due to some numerical approximations. However, the evaluations of the uncertainties and their correlations are still challenging issues. In addition, there would be unknown uncertainties that experimenters and analysts of reactor physics experiments could not recognize. To judge the goodness of the covariance matrix related to these uncertainties, the applicability of ABIC to the cross-section adjustment method was investigated.
Fukui, Yuhei*; Endo, Tomohiro*; Yamamoto, Akio*; Maruyama, Shuhei
EPJ Web of Conferences, 281, p.00006_1 - 00006_9, 2023/03
We developed a new nuclear data adjustment method for experimental data containing outliers. This method mitigates the effect of outliers by applying M-estimation, a type of robust estimation, to the conventional nuclear data adjustment method using sensitivity coefficients. Based on the M-estimation, we derived a weighted nuclear data adjustment formula and developed a weight calculation method. The weighted nuclear data adjustment formula was derived by weighting the function to take the extremum of the conventional nuclear data adjustment. The weighting of each nuclear characteristic is calculated from the difference between the measured and calculated values of the nuclear characteristic. This weight calculation method can evaluate the validity of each nuclear characteristic by considering correlations between nuclear characteristics using singular value decomposition. The proposed method and the conventional method were compared and verified by twin experiments. In the twin experiments, the nuclear data were adjusted using experimental data that intentionally included outliers. As a result of twin experiments, it was confirmed that the nuclear data were adjusted robustly and appropriately even with the experimental data containing outliers.
Miyazaki Noriyuki*; Hagiwara Seiya*; Chino, Eiichi*; Maruyama, Yu*; Hashimoto, Kazuichiro*; Maeda, Akio*
JAERI-Research 2001-047, 35 Pages, 2001/10
JAERI-Research-2001-047.pdf:1.63MB
no abstracts in English
Chino, Eiichi; Maruyama, Yu; Maeda, Akio*; Harada, Yuhei*; Nakamura, Hideo; Hidaka, Akihide; Shibazaki, Hiroaki*; Yuchi, Yoko; Kudo, Tamotsu; Hashimoto, Kazuichiro*
Proceedings of the 7th International Conference on Creep and Fatigue at Elevated Temperatures (CREEP7), p.107 - 115, 2001/06
no abstracts in English
Shibazaki, Hiroaki*; Maruyama, Yu; Kudo, Tamotsu; Hashimoto, Kazuichiro*; Maeda, Akio*; Harada, Yuhei*; Hidaka, Akihide; Sugimoto, Jun
Nuclear Technology, 134(1), p.62 - 70, 2001/04
Times Cited Count：3 Percentile：27.07(Nuclear Science & Technology)no abstracts in English
Harada, Yuhei*; Maruyama, Yu; Maeda, Akio*; Chino, Eiichi; Shibazaki, Hiroaki*; Kudo, Tamotsu; Hidaka, Akihide; Hashimoto, Kazuichiro; Sugimoto, Jun
JAERI-Conf 2000-015, p.309 - 314, 2000/11
no abstracts in English
Chino, Eiichi; Maruyama, Yu; Yuchi, Yoko; Shibazaki, Hiroaki*; Nakamura, Hideo; Hidaka, Akihide; Kudo, Tamotsu; Hashimoto, Kazuichiro; Maeda, Akio*
JAERI-Conf 2000-015, p.303 - 308, 2000/11
no abstracts in English
Harada, Yuhei; Maruyama, Yu; Maeda, Akio*; Chino, Eiichi; Shibazaki, Hiroaki*; Kudo, Tamotsu; Hidaka, Akihide; Hashimoto, Kazuichiro; Sugimoto, Jun
Journal of Nuclear Science and Technology, 37(6), p.518 - 529, 2000/06
no abstracts in English
Harada, Yuhei; Maruyama, Yu; Maeda, Akio; Shibazaki, Hiroaki*; Kudo, Tamotsu; Hidaka, Akihide; Hashimoto, Kazuichiro; Sugimoto, Jun
Journal of Nuclear Science and Technology, 36(10), p.923 - 933, 1999/10
Times Cited Count：3 Percentile：28.69(Nuclear Science & Technology)no abstracts in English
Hashimoto, Kazuichiro; Harada, Yuhei; Maeda, Akio; Maruyama, Yu; Shibazaki, Hiroaki*; Kudo, Tamotsu; Hidaka, Akihide; Sugimoto, Jun
JAERI-Conf 99-005, p.161 - 164, 1999/07
no abstracts in English
Harada, Yuhei; Maruyama, Yu; Maeda, Akio; Shibazaki, Hiroaki*; Kudo, Tamotsu; Hidaka, Akihide; Hashimoto, Kazuichiro; Sugimoto, Jun
JAERI-Conf 99-005, p.171 - 175, 1999/07
no abstracts in English
Maeda, Akio; Maruyama, Yu; Hashimoto, Kazuichiro; Harada, Yuhei; Shibazaki, Hiroaki*; Kudo, Tamotsu; Nakamura, Naohiko; Hidaka, Akihide; Sugimoto, Jun
JAERI-Conf 99-005, p.165 - 170, 1999/07
no abstracts in English
Shibazaki, Hiroaki*; Maruyama, Yu; Kudo, Tamotsu; Hashimoto, Kazuichiro; Maeda, Akio; Harada, Yuhei; Hidaka, Akihide; Sugimoto, Jun
JAERI-Conf 99-005, p.191 - 196, 1999/07
no abstracts in English
Kudo, Tamotsu; Shibazaki, Hiroaki*; Hidaka, Akihide; Maruyama, Yu; Maeda, Akio; Harada, Yuhei; Hashimoto, Kazuichiro; Sugimoto, Jun; Yoshino, T.*; Suzuki, K.*
JAERI-Conf 99-005, p.197 - 201, 1999/07
no abstracts in English
Maruyama, Yu; Shibazaki, Hiroaki*; Igarashi, Minoru*; Maeda, Akio; Harada, Yuhei; Hidaka, Akihide; Sugimoto, Jun; Hashimoto, Kazuichiro*; Nakamura, Naohiko*
Journal of Nuclear Science and Technology, 36(5), p.433 - 442, 1999/05
Times Cited Count：9 Percentile：57.31(Nuclear Science & Technology)no abstracts in English
