RSICC CODE PACKAGE PSR-490

1. NAME AND TITLE

MINET: Momentum Integral Network Method for Thermal-Hydraulic Systems Analysis.

2. CONTRIBUTORS

Brookhaven National Laboratory, Upton, New York, through the Energy Science and Technology Software Center, Oak Ridge, Tennessee.

3. CODING LANGUAGE AND COMPUTER

Fortran 66; CRAY Y-MP

Fortran 77 (99%) and BAL (%1); IBM3090

(P00490CY00000)

4. NATURE OF PROBLEM SOLVED

MINET (Momentum Integral NETwork) was developed for the transient analysis of intricate fluid flow and heat transfer networks, such as those found in the balance of plant in power generating facilities. It can be utilized as a stand-alone program or interfaced to another computer program for concurrent analysis. Through such coupling, a computer code limited by either the lack of required component models or large computational needs can be extended to more fully represent the thermal hydraulic system thereby reducing the need for estimating essential transient boundary conditions. The MINET representation of a system is one or more networks of volumes, segments, and boundaries linked together via heat exchangers only, i.e., heat can transfer between networks, but fluids cannot. Volumes are used to represent tanks or other volume components, as well as locations in the system where significant flow divisions or combinations occur. Segments are composed of one or more pipes, pumps, heat exchangers, turbines, and/or valves each represented by one or more nodes. Boundaries are simply points where the network interfaces with the user or another computer code. Several fluids can be simulated, including water, sodium, NaK, and air.

5. METHOD OF SOLUTION

MINET is based on a momentum integral network method. Calculations are performed at two levels, the network level (volumes) and the segment level. Equations conserving mass and energy are used to calculate pressure and enthalpy within volumes. An integral momentum equation is used to calculate the segment average flow rate. In-segment distributions of mass flow rate and enthalpy are calculated using local equations of mass and energy. The segment pressure is taken to be the linear average of the pressure at both ends. This method uses a two-plus equation representation of the thermal hydraulic behavior of a system of heat exchangers, pumps, pipes, valves, tanks, etc. With the exception of variables which are control system related, such as pump speed, the system represented is closed and accessed only through boundary modules. MINET uses a homogeneous equilibrium model of two-phase flow, supplemented by various two-phase correlations.

6. RESTRICTIONS OR LIMITATIONS

Maxima of 5 heat exchanger options, 3 heat exchanger tube configuration options and 2 turbine stage types. At least one inlet and one outlet boundary must be included in each fluid network. The MINET methodology is geared toward solving one-dimensional flow network problems (e.g., balance of plant) under non-blowdown transient conditions. Pressure waves are not tracked locally. It is implicitly assumed that the propagation of pressure waves in pipes, pumps, heat exchangers, and valves takes place on a time scale much smaller (milliseconds) than the transient of interest (seconds).

7. TYPICAL RUNNING TIME

Running time varies depending on the detail specified and the transient simulated. NESC executed the sample problem in 5 CPU seconds on a Cray Y-MP. NESC executed the sample problem in 17 CPU minutes on an IBM4331.

8. COMPUTER HARDWARE REQUIREMENTS

MINET requires 152 Kbytes of memory on a Cray Y-MP. MINET requires 1349 Kbytes of memory on an IBM4331.

9. COMPUTER SOFTWARE REQUIREMENTS

The Cray version ran under Unicos 4.0 with the CFT compiler and will not run with CFT77. The IBM mainframe version runs under VM/CMS and requires a Fortran compiler and Basic Assembler for subroutines ICLOCK, IDAY and TIME to return elapsed CPU time, current date, and time, respectively.

10. REFERENCES

a) included with package:

G. J. Van Tuyle, T. C. Nepsee, and J. G. Guppy, "MINET Code Documentation," NUREG/CR-3668 (BNL-NUREG-51742) (December 1989).

b) background information:

G. J. Van Tuyle, "A Momentum Integral Network Method for Thermal-Hydraulic Systems Analysis, Nuclear Engineering and Design," Vol. 91, pp. 17-28 (1986).

11. CONTENTS OF CODE PACKAGE

Included are the referenced document in (10 a.) and software on one 3.5-inch HD diskette containing a PkWare WINDOWS ® self-extracting executable with Cray and IBM mainframe source and sample problem files. No executable files are included in this package.

12. DATE OF ABSTRACT

MINET was first distributed by NESC September 1989 and later transferred to ESTSC then to RSICC where it was screened and released November 2000. It was not tested at RSICC.

KEYWORDS: FLUID DYNAMICS; HEAT TRANSFER; LWR; REACTOR PHYSICS; REACTOR SAFETY