RSICC CODE PACKAGE PSR-400

1. NAME AND TITLE

SSC-L V3.3: Transient Response in LMFBR System.

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 77 (99.8%) and BAL (0.2%); IBM3090 (P00400I309000).

4. NATURE OF PROBLEM SOLVED

SSC-L (the Super System Code) calculates the thermohydraulic response of loop-type liquid metal fast breeder reactor (LMFBR) systems during operational, incidental, and accidental transients, especially natural circulation events. Modules simulated and parameters calculated include: core flow rates and temperatures, loop flow rates and temperatures, pump performance, and heat exchanger operation. Additionally, SSC-L accounts for all plant protection and plant control systems. Although the primary emphasis is on transients for safety analysis, SSC-L can be used for many other applications, such as scoping analysis for plant design and specification of various components. Any number of user-specified loops, pipes, and nodes are permitted. Both single- and two-phase thermal-hydraulics are used in a multi-channel core representation. Inter-assembly flow redistribution is accounted for using a detailed fuel pin model. The heat transport system geometry is user-specified. SSC-L provides steady-state and transient options and a restart capability. Input is free format in a modular structure that makes use of abstract data management techniques.

5. METHOD OF SOLUTION

The simulation of an entire LMFBR is, by its very nature, complex. Physically, a plant consists of many subsystems which are coupled by various processes and/or components. Mathematically, each subsystem constitutes a set of differential equations with appropriate boundary conditions. SSC-L solves each component subsystem with the most suitable algorithm for the process under consideration. For example, the heat conduction equations for a fuel rod are solved by a fully implicit weighted residuals scheme. The fission heating computation, on the other hand, can be computed by a modified Kaganove algorithm which uses a polynomial method or by a prompt jump approximation. The interfacing of all the processes is achieved by matching boundary conditions at the respective interfaces. The overall timestep is controlled by requiring solutions to be numerically stable as well as by user-specified accuracy criteria.

6. RESTRICTIONS OR LIMITATIONS

Maxima of 21 protective functions and 6 delayed neutron groups. SSC-L was developed for one-dimensional geometries, and the results are not valid after cladding degradation.

7. TYPICAL RUNNING TIME

IBM: NESC executed the sample problem in 5.2 CPU hours on an IBM4331.

8. COMPUTER HARDWARE REQUIREMENTS

SSC-L requires 3608 Kbytes of memory on an IBM4331.

9. COMPUTER SOFTWARE REQUIREMENTS

IBM: VM/CMS

10. REFERENCES

a) included in document:

J.G. Guppy, "Super System Code (SSC, Rev. 0) An Advanced Thermohydraulic Simulation Code for Transients in LMFBRs," NUREG/CR-3169 (BNL-NUREG-51650) (April 1983).

G.J. VanTuyle, T.C. Nepsee, and J.G. Guppy, "MINET Code Documentation," NUREG/CR-3668 (BNL-NUREG-51742) (February 1984).

b) background:

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

11. CONTENTS OF CODE PACKAGE

Included are the reference documents in (10.a) and source, sample problem, and control information on one diskette as a self-extracting compressed DOS file.

12. DATE OF ABSTRACT

April 1999.

KEYWORDS: THERMAL HYDRAULICS; HEAT TRANSFER