United States Nuclear Regulatory Commission - Protecting People and the Environment

PUFF-III: A Code for Processing ENDF Uncertainty Data Into Multigroup Covariance Matrices (NUREG/CR-6650)

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Publication Information

Manuscript Completed: April 2000
Date Published: June 2000

Prepared by:
M. E. Dunn

Oak Ridge National Laboratory
Managed by UT-Battelle, LLC
Oak Ridge, TN 37831-6370

D. D. Ebert, NRC Project Manager

Prepared for:
Division of Systems Analysis and Regulatory Effectiveness
Office of Nuclear Regulatory Research
U.S. Nuclear Regulatory Commission
Washington, DC 20555-0001

NRC Job Code W6479

Availability Notice

Abstract

PUFF-III is an extension of the previous PUFF-Il code that was developed in the 1970s and early 1980s. The PUFF codes process the Evaluated Nuclear Data File (ENDF) covariance data and generate multigroup covariance matrices on a user-specified energy grid structure. Unlike its predecessor, PUFF-ill can process the new ENDF/B-VI data formats. In particular, PUFF-III has the capability to process the spontaneous fission covariances for fission neutron multiplicity. With regard to the covariance data in File 33 of the ENDF system, PUFF-III has the capability to process short-range variance formats, as well as the lumped reaction covariance data formats that were introduced in ENDF/B-V. In addition to the new ENDF formats, a new directory feature is now available that allows the user to obtain a detailed directory of the uncertainty information in the data fides without visually inspecting the ENDF data. Following the correlation matrix calculation, PUFF-rn also evaluates the eigenvalues of each correlation matrix and tests each matrix for positive definiteness. Additional new features are discussed in the manual. PUFF-Ill has been developed for implementation in the AMPX code system, and several modifications were incorporated to improve memory allocation tasks and input/output (I/O) operations. Consequently, the resulting code has a structure that is similar to other modules in the AMPX code system. With the release of PUFF-III, a new and improved covariance processing code is available to process ENDF covariance formats through Version VI.

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