**RSICC CODE PACKAGE PSR-402**

**1. NAME AND TITLE**

BEACON/MOD3: Code System for Thermal-Hydraulic Analysis of Nuclear Reactor Containments.

**2. CONTRIBUTORS**

Idaho National Engineering Laboratory, Idaho Falls, Idaho through the Energy Science and Technology Software Center, Oak Ridge, Tennessee.

**3. CODING LANGUAGE AND COMPUTER**

FORTRAN IV (98%) and COMPASS (2%); CDC CYBER176 (P00402CDCMF00).

**4. NATURE OF PROBLEM SOLVED**

The BEACON series of programs is designed to perform a best-estimate analysis of the flow of a mixture of air, water, and steam in a nuclear reactor containment system under loss-of-coolant accident conditions. The code can simulate two-component, two-phase fluid flow in complex geometries using a combination of two-dimensional, one-dimensional, and lumped-parameter representations for the various parts of the system. BEACON/MOD3 contains mass and heat transfer models for wall film and for wall conduction and is suitable for the evaluation of short-term transients in PWR dry containment systems. The capability to examine the details of a two-component, two-phase flow field in one or two dimensions under nonhomogeneous, nonequilibrium conditions (unequal velocities, unequal temperatures between the two phases) allows analysis of such problems as the calculation of jet impact forces of a fluid leaving a pipe break, the motion of a large pressure wave across a compartment, the variation in flow properties as air is displaced from a compartment by steam and water, the water entrainment or deentrainment by a high-speed vapor flow, the flow of a flashing liquid, and many other complex nonequilibrium problems of containment system analyses.

**5. METHOD OF SOLUTION**

The basic Eulerian flow solution procedure is based on the K-FIX two-dimensional two-phase numerical method. Each phase is described by its own density, velocity, and temperature as determined by separate sets of mass, momentum, and energy equations. The two phases are coupled by exchange parameters which model the exchange of mass, momentum, and energy between the two phases. The two sets of field equations are solved with a Eulerian finite-difference technique that implicitly treats the phase transitions and interphasic heat transfer in the pressure iteration. The implicit solution is accomplished iteratively without linearization and allows both phases to be compressible. The coupling between the two phases can be very loose, as occurs with separated flow, or very tight as with finely dispersed flow. Computations for single phase gas flow can also be obtained without special treatment. BEACON can handle air as a second vapor component.

**6. RESTRICTIONS OR LIMITATIONS**

BEACON/MOD3 does not have pressure suppression containment models. The Eulerian computational equations have been modified for the variable nodalization of a mesh with the spatial dimensions of each cell stored in row-wide and column-wide arrays. Neither dimension should vary between adjacent cells by more than a factor of two. The centers of adjacent cells must align either in the radial (abscissa) or vertical (ordinate) direction, and no mesh may have more than 50 interior cells in either direction. The coupling of the Eulerian regions must be on a cell-to-cell basis. Due to the array sizes in the code, maxima of 20 Eulerian regions and 20 lumped-parameter regions are allowed per problem setup. The total number of cells (nodes) in all Eulerian regions is limited to 2184.

**7. TYPICAL RUNNING TIME**

Running time is highly-variable depending on problem complexity. NESC executed the 8 sample problems in 4 CP minutes on a CDC7600.

**8. COMPUTER HARDWARE REQUIREMENTS**

120,000 (octal) words of SCM and 34,000 (octal) words of LCM for the largest of the eight sample problems. The LCM required is a function of the program size (i.e., the number of nodes or computational cells) and is dynamically allocated by the BEACON code.

**9. COMPUTER SOFTWARE REQUIREMENTS**

The system ran under NOS/BE (CDC CYBER176); SCOPE 2.1 (CDC7600) and requires Fortran IV and Compass compilers.

**10. REFERENCES**

**a) included in documentation:**

C. R. Broadus, R. J. Doyle, S. W. James, J. F. Lime, W. J. Mings, J. A. Ramsthaler, and M. S. Sahota, "BEACON/MOD3: A Computer Program for Thermal-Hydraulic Analysis of Nuclear Reactor Containments - User's Manual," NUREG/CR-1148 (EGG-2008) (April 1980).

BEACON/MOD3, NESC No. 767.C176, BEACON/MOD3 Tape Description and Sample Problem Output, National Energy Software Center Note 82-22 (November 19, 1981).

**b) background reference**:

INEL-IGS, Idaho National Engineering Laboratory, Integrated Graphics System Programming Guide, Aerojet Nuclear Company Computer Science Center (March 1976).

W.C. Rivard and M.D. Torrey, "K-FIX: A Computer Program for Transient Two-Dimensional, Two-Fluid Flow, LA-NUREG-6623, NRC-4 (April 1977).

F.H. Harlow and A.A. Amsden, "Numerical Calculation of Multiphase Fluid Flow," Journal of Computational Physics, Vol. 17, pp. 19-52, 1975.

**11. CONTENTS OF CODE PACKAGE**

Included are the referenced documents in (10.a) and one DS/HD diskette on which the CDC Fortran source and sample problem input and output are written as a self-extracting, compressed DOS file.

**12. DATE OF ABSTRACT**

October 2000.

** KEYWORDS:** HEAT TRANSFER; LOCA; REACTOR SAFETY; THERMAL
HYDRAULICS