SYMPOSIA PAPER Published: 01 January 2007

A New Derivation of the Perturbation Operator Used in MCNP


A new derivation of the perturbation operator used in the MCNP radiation transport code is presented, and equations are determined to evaluate the change in the response from a perturbation in macroscopic cross section due to the first, second, third, and fourth derivative terms, and the second-derivative cross term. The perturbation operator in MCNP currently can be used to determine the change in a response from the first and second order terms in Taylor expansion due to such a perturbation. The derivation presented here produces expressions that are equivalent to the expressions used in MCNP for the first and second derivative, but are simpler and are in a form that more readily reveals their physical significance. The perturbation operator is particularly useful for sensitivity and uncertainty analysis.

Author Information

Keith, Robert, E.
ITT Industries, AES, Colorado Springs, CO
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Developed by Committee: E10
Pages: 276–285
DOI: 10.1520/STP45454S
ISBN-EB: 978-0-8031-6242-6
ISBN-13: 978-0-8031-3412-6