16.07.2013 Views

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

SHOW MORE
SHOW LESS

Create successful ePaper yourself

Turn your PDF publications into a flip-book with our unique Google optimized e-Paper software.

<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.

Hooray! Your file is uploaded and ready to be published.

Saved successfully!

Ooh no, something went wrong!