JAEA-Conf 2011-002 - 日本原子力研究開発機構
JAEA-Conf 2011-002 - 日本原子力研究開発機構
JAEA-Conf 2011-002 - 日本原子力研究開発機構
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<strong>JAEA</strong>-<strong>Conf</strong> <strong>2011</strong>-<strong>002</strong><br />
Sensitivity Analysis for Higher Order Legendre Coefficients<br />
of Elastic Scattering Matrices<br />
Go CHIBA<br />
Research Group for Reactor Physics, Japan Atomic Energy Agency<br />
Tokai-mura, Naka-gun, Ibaraki-ken 319-1195<br />
e-mail: chiba.go@jaea.go.jp<br />
A sensitivity analysis is carried out focusing on higher order Legendre coefficients of elastic<br />
scattering matrices. Non-negligible library effects, which are defined as differences in<br />
criticalities caused by differences in nuclear data of different libraries, are observed in higher<br />
order Legendre coefficients of elastic scattering matrices of uranium-238 and iron-56 between<br />
JENDL-4.0 and the other modern nuclear data files. It is also found that an attention should be<br />
paid to the type of multi-group cross sections used for library effect calculations. It is concluded<br />
that higher order Legendre coefficients should be accounted for if accurate library effect evaluation<br />
is required.<br />
1. Introduction<br />
The nuclear data is usually stored in the evaluated nuclear data files with the so-called ENDF<br />
format. There are several evaluated nuclear data files such as JENDL, ENDF and JEFF in the<br />
world. These libraries have been updated along with the improvement on the nuclear reaction<br />
models, the evaluation codes and the experimental data used for nuclear data evaluations. Since<br />
the nuclear data is the physical quantity, the evaluated nuclear data may converge to the true<br />
values by their improvement. While the latest evaluated nuclear data files such as JENDL-4.0,<br />
ENDF/B-VII.0 and JEFF-3.1 have quite high qualities, there are still large differences among<br />
them, and these differences significantly affect integral parameters calculated with these nuclear<br />
data files.<br />
Sensitivity analyses are useful to investigate causes of differences in integral parameters<br />
among different nuclear data files, and they have been effectively carried out in order to improve<br />
the qualities of the nuclear data files. In the usual sensitivity analyses, various kinds of the<br />
nuclear data have been accounted for. Scattering matrices and the first order Legendre<br />
coefficients of them have been also treated. Higher order Legendre coefficients of scattering<br />
matrices however have been ignored since the contributions of these data are supposed to be<br />
negligibly small.<br />
In the present paper, a sensitivity analysis is carried out focusing on higher order Legendre<br />
coefficients of elastic scattering matrices. Criticalities of various fast neutron systems are<br />
calculated with the modern nuclear data files, JENDL-4.0, -3.3, ENDF/B-VII.0 and JEFF-3.1, and<br />
differences in the calculated values are investigated from a view point of a difference in higher<br />
order Legendre coefficients of elastic scattering matrices.