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Journal Articles

Comparative study on prediction accuracy improvement methods with the use of integral experiments for neutronic characteristics of fast reactors

Yokoyama, Kenji; Kitada, Takanori*

Proceedings of 2018 International Congress on Advances in Nuclear Power Plants (ICAPP 2018) (CD-ROM), p.1221 - 1230, 2018/04

no abstracts in English

Journal Articles

Dimension-reduced cross-section adjustment method based on minimum variance unbiased estimation

Yokoyama, Kenji; Yamamoto, Akio*; Kitada, Takanori*

Journal of Nuclear Science and Technology, 55(3), p.319 - 334, 2018/03

 Times Cited Count:2 Percentile:44.8(Nuclear Science & Technology)

A new formulation of the cross-section adjustment methodology with the dimensionality reduction technique has been derived. This new formulation is proposed as the dimension reduced cross-section adjustment method (DRCA). Since the derivation of DRCA is based on the minimum variance unbiased estimation (MVUE), an assumption of normal distribution is not required. The result of DRCA depends on a user-defined matrix that determines the dimension reduced feature subspace. We have examine three variations of DRCA, namely DRCA1, DRCA2, and DRCA3. Mathematical investigation and numerical verification have revealed that DRCA2 is equivalent to the currently widely used cross-section adjustment method. Moreover, DRCA3 is found to be identical to the cross-section adjustment method based on MVUE, which has been proposed in the previous study.

Journal Articles

A New cross section adjustment method of removing systematic errors in fast reactors

Takeda, Toshikazu*; Yokoyama, Kenji; Sugino, Kazuteru

Annals of Nuclear Energy, 109, p.698 - 704, 2017/11

 Times Cited Count:0 Percentile:100(Nuclear Science & Technology)

A new cross section adjustment method has been derived in which systematic errors in measured data and calculated results of neutronics characteristics are estimated and removed in the adjustment. Bias factors which are the ratio between measured data and calculated results are used to estimate systematic errors. The difference of the bias factors from unity is caused generally by systematic errors and stochastic errors. Therefore by determining whether the difference is within the total stochastic errors of measurements and calculations, systematic errors are estimated. Since stochastic errors are determined for individual confidence levels, systematic errors are also dependent to the confidence levels. The method has been applied to cross section adjustments using 589 measured data obtained from fast critical assemblies and fast reactors. The adjustments results are compared with those of the conventional adjustment method. Also the effect of the confidence level to the adjusted cross sections is discussed.

Journal Articles

Methods and approaches to provide feedback from nuclear and covariance data adjustment for improvement of nuclear data files

Palmiotti, G.*; Salvatores, M.*; Yokoyama, Kenji; Ishikawa, Makoto

NEA/NSC/R(2016)6 (Internet), 42 Pages, 2017/05

Journal Articles

Development of a fast reactor for minor actinides transmutation; Improvement of prediction accuracy for MA-related integral parameters based on cross-section adjustment technique

Yokoyama, Kenji; Maruyama, Shuhei; Numata, Kazuyuki; Ishikawa, Makoto; Takeda, Toshikazu*

Proceedings of International Conference on the Physics of Reactors; Unifying Theory and Experiments in the 21st Century (PHYSOR 2016) (USB Flash Drive), p.1906 - 1915, 2016/05

Journal Articles

Adjustment of total delayed neutron yields of $$^{235}$$U, $$^{238}$$U and $$^{239}$$Pu by using results of in-pile measurements of effective delayed neutron fraction

Sakurai, Takeshi; Okajima, Shigeaki

Proceedings of International Conference on the New Frontiers of Nuclear Technology; Reactor Physics, Safety and High-Performance Computing (PHYSOR 2002) (CD-ROM), 12 Pages, 2002/10

The cross section adjustment method was applied to total delayed neutron yields of $$^{235}$$U, $$^{238}$$U and $$^{239}$$Pu of the JENDL-3.2 file by using experimental results of effective delayed neutron fraction $$beta_{eff}$$ at six cores built in two fast critical facilities of the MASURCA and FCA and a thermal critical facility of the TCA to improve these yields. The adjustment was carried out on the yields given at several incident neutron energy points in the file. Furthermore, to validate these adjusted delayed neutron yields, analyses were performed for the $$beta_{eff}$$ experiments at ZPR fast critical facility. These adjusted yields brought a reduction of uncertainty of calculated $$beta_{eff}$$ and an improvement in agreement of $$beta_{eff}$$ between experiment and calculation.

Journal Articles

Adjustment of total delayed neutron yields of $$^{235}$$U, $$^{238}$$U and $$^{239}$$Pu in JENDL-3.2 using benchmark experiments on effective delayed neutron fraction $$beta_{eff}$$

Sakurai, Takeshi; Okajima, Shigeaki

Journal of Nuclear Science and Technology, 39(1), p.19 - 30, 2002/01

 Times Cited Count:5 Percentile:62.25(Nuclear Science & Technology)

The cross section adjustment method was applied to total delayed neutron yields of $$^{235}$$U, $$^{238}$$U and $$^{239}$$Pu of the JENDL-3.2 file by using experimental results of effective delayed neutron fraction $$beta_{eff}$$ at six cores built in two fast critical facilities of the MASURCA and FCA and a thermal critical facility of the TCA to improve these yields. The adjustment was carried out on the yields given at several incident neutron energy points in the file. After the adjustment, the yield of $$^{238}$$U was almost uniformly decreased by about 3% below 7 MeV. The yield of $$^{239}$$Pu was increased by 2.6% and that of $$^{235}$$U was decreased by 0.9% at the thermal energy point, while the change of yield was less than 0.3% at the other energy points for these nuclides. By using these adjusted yields, the uncertainty of calculated $$beta_{eff}$$ was reduced and the agreement of $$beta_{eff}$$ between experiment and calculation was improved.

Journal Articles

Adjustment to cross section data to fit integral experiments by least squares method

;

Journal of Nuclear Science and Technology, 12(11), p.663 - 680, 1975/11

 Times Cited Count:12

no abstracts in English

Oral presentation

JENDL-4.0 based cross-section adjustment by adding new experiments on the basis of the SG33 benchmark

Yokoyama, Kenji; Numata, Kazuyuki; Ishikawa, Makoto

no journal, , 

no abstracts in English

Oral presentation

A "Tiny" adjustment of nuclear data and associated correlation factor

Yokoyama, Kenji; Ishikawa, Makoto

no journal, , 

no abstracts in English

10 (Records 1-10 displayed on this page)
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