United States Nuclear Regulatory Commission - Protecting People and the Environment

TRAC-M/FORTRAN 90 (Version 3.0) User's Manual (NUREG/CR-6722)

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Publication Information

Manuscript Completed: March 2001
Date Published: May 2001

Prepared by:
R.G. Steinke, V. Martinez, N.M. Schnurr,
J.W. Spore, J.V. Valdez

Los Alamos National Laboratory
Los Alamos, New Mexico 87545

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 Transient Reactor Analysis Code (TRAC) was developed to provide advanced best-estimate predictions of postulated accidents in light-water reactors. The TRAC-M program provides this capability for pressurized water reactors and for many thermal-hydraulic test facilities. The code features either a one-, two-, or three-dimensional treatment of the pressure vessel and its associated internals; a two-fluid nonequilibrium hydrodynamics model with a noncondensable gas field and solute tracking; flow-regime-dependent constitutive-equation treatment; optional reflood-tracking capability for bottom-flood and falling-film quench fronts, and consistent treatment of entire accident sequences, including the generation of consistent steady-state initial conditions. The stabilityenhancing, two-step numerical algorithm is used in the one-, two-, and three-dimensional hydrodynamics and permits violation of the material Courant-limit condition up to 1000. This technique permits large timesteps, which reduce the run time for slow transients.

TRAC-M no longer models the accumulator (ACCUM) component and steam-generator (STGEN) component. The ACCUM component needs to be modeled by FILL and PIPE components, and the STGEN component needs to be modeled by using heat-structure (HTSTR), PIPE, and TEE components, as described in Appendix I. The HTSTR component provides the user with a very flexible capability to model heat transfer in complicated geometries with many optional features. An improved reflood model based on mechanistic and defensible models has been added. TRAC-M also contains additions and refinements for several components and improved constituative models. A steady-state initialization procedure provides a better coolant temperature and flow distribution initial estimate for steady-state calculations.

This user's guide describes the components and control systems modeled in TRAC-M and gives detailed information the user needs to prepare an input-data file and carry out neutronic-thermal-hydraulic simulations using TRAC-M. This release of the TRAC-M/F90 User's Manual is consistent with TRAC-M/F90, Version 3.0. Also, areas are described where TRAC-M/F90, Version 3.0 differs from TRAC-M/F77, Version 5.5.2, and input specifications are provided for both codes.

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