| Autor: |
KELSEY IV, CHARLES T., PRINJA, ANIL K. |
| Předmět: |
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| Zdroj: |
Nuclear Technology; Nov2009, Vol. 168 Issue 2, p257-263, 7p, 2 Diagrams, 7 Graphs |
| Abstrakt: |
The limited availability of coupled multigroup proton/ neutron cross-section libraries has hampered the use of deterministic transport methods for solving shielding problems involving energetic proton sources. Libraries are developed from evaluated nuclear data for low-energy transport and the physics models of MCNPX for intermediate-energy transport. They allow deterministic solutions of orbiting spacecraft shielding problems. Evaluated cross sections for protons and neutrons are available for many nuclides up to 150 Me V. N JOY99 is used to produce coupled multigroup proton/neutron cross sections from these. For higher energies, MCNPX is run in its cross-section calculation mode where the XSEX3 program is used to tally double-differential cross sections. The XSEX3 program was modified to discretize the cross sections in energy and output Legendre expansions for angular dependence. The N JOY99 and modified XSEX3 output are combined to produce cross-section libraries for energies up to 400 MeV. The libraries are used to solve trapped proton flux shielding problems using the discrete ordinates transport code Attila. High-order Legendre expansions (P39) are required to accurately describe the highly anisotropic scattering. Attila applies the extended transport correction allowing accurate three-dimensional solutions at much lower degrees. Particle flux solutions for orbiting spacecraft shielding problems obtained with Attila and MCNPX compare favorably. Coupled multigroup proton/neutron cross-section libraries, for use with deterministic transport codes, can be prepared using N JOY99 and MCNPX. Our results using the Attila code demonstrate that multigroup deterministic methods are computationally efficient alternatives to Monte Carlo simulation. [ABSTRACT FROM AUTHOR] |
| Databáze: |
Supplemental Index |
| Externí odkaz: |
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