United States Nuclear Regulatory Commission - Protecting People and the Environment

TRAC-M/FORTRAN 90 Version 3.0 Theory Manual (NUREG/CR-6724)

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Publication Information

Manuscript Completed: April 2001
Date Published: July 2001

Prepared by:
J.W. Spore, J.S. Elson, SJ. Jolly-Woodruf, T.D. Knight
J.C. Lin, RA Nelson, K.Q. Pasamehmetoglu, LANL

J.H. Mahaffy, C. Murray, PSU

Los Alamos National Laboratory
Los Alamos, New Mexico 87545

Pennsylvania State University
University Park, PA 16802

F. Odar, 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 W6245

Availability Notice


The United States Nuclear Regulatory Commission (USNRC) is developing the modernized versions of the Transient Reactor Analysis Code (TRAC-M) to provide advanced best-estimate simulations of real and postulated transients in pressurized and boiling water reactors (PWRs and BWRs) and for many related thermal-hydraulic facilities. The TRAC-M/ Fortran 90 (TRAC-M/F90) program, the latest released version, is written for TRAC-M/F90 Version 3.0. In addition, we indicate areas where TRAC-M/F90 differs from the TRAC-M Fortran 77 (TRAC-M/F77) code (Version 5.5.2). Both codes feature a one- and/or three-dimensional, twofluid treatment for the thermal hydraulics, together with other necessary modeling capabilities to describe a reactor system. Currently both codes are intended for analysis of pressurized water reactors (PWRs), but future versions of TRAC-M/F90 will include a capability to model BWRs. Both codes produce graphics output that is compatible with the TRAC visualization and plotting tool XTV. In addition, TRAC-M/F90's graphics file can be used with the XMGR code. TRAC-M/F77 is written in standard Fortran 77 and includes a newly enhanced reflood model. TRAC-M/F90 is written in standard Fortran 90 and includes a derived-type database and improved data interfaces.

This report is one of four describing various features of TRAC-M/F90. Two of the other documents are the TRAC-M/F90 User's and Programmer's Manuals. The fourth document is the TRAC-M/F77 Developmental Assessment Manual. This Theory Manual provides a detailed description of the field equations, solution procedure, numerics, and closure correlations and models of the code. This report also provides the basis for each model, correlation, or solution strategy through references to original literature and/or a description of the development process. Additionally, it lists the assumptions made in the implementation, including the definitions of required parameters not normally calculated by the code, and it describes other details of the implementation. We have provided a partial assessment of some of the models and correlations against other pertinent models and correlations or separate-effects data. However, a true measure of the overall accuracy of the code must include assessment of the code against integral experimental data because of synergistic effects. Such assessment results are provided in the TRAC-M/ F77 Developmental Assessment Manual.

In the process of reviewing the details for the code and writing this report, we found that the numerics and the models and correlations used in the code are a good representation of the state of the art. However, simplified models are used in some areas where either a relevant model was not found in the literature or the literature model could not be implemented easily into the code's logic. From the assessment against integral tests, we believe that TRAC-M/F90 is a viable calculational tool for analyzing pressurized light-water reactors (LWRs) during a loss-of-coolant accident and operational tru.isients. (Future releases of the TRAC-M/F90 documentation will address boiling water reactor (BWR) analysis.) In addition, the developmental assessment calculations for TRAC-M/F77 indicate that TRAC-M/F90 will be applicable to a wide range of test facilities.

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