RSICC CODE PACKAGE PSR-516

1. NAME AND TITLE

PARET-ANL: Code System to Predict Consequences of Nondestructive Accidents in Research and Test Reactor Cores.

2. CONTRIBUTORS

Argonne National Laboratory, Argonne, Illinois.

3. CODING LANGUAGE AND COMPUTER

Unix, Linux and Windows (P00516/MNYCP/00).

4. NATURE OF PROBLEM SOLVED

This program is designed for use in predicting the course of and consequence of nondestructive accidents in research and test reactor cores. This code is an extension of the original PARET code (NESC Abstract 555). The code system now includes a properties library generator for both light and heavy water coolants, and a post processing code for extracting selected data from a summary file for further analysis or plotting.

5. METHOD OF SOLUTION

The code provides a coupled thermal, hydrodynamic and point kinetics capability. The core can be represented by one to four regions. Each region may have different power generation, coolant mass flow rate and hydraulic parameters as represented by a single fuel pin or plate with associated coolant channel. The heat transfer in each fuel element is computed on the basis of a one-dimensional solution in each of up to 21 axial sections. The hydrodynamics solution is also one-dimensional for each channel at each time node. The heat transfer may take place by natural or forced convection, nucleate, transition or stable film boiling, and the coolant is allowed to range from sub-cooled liquid, through the two-phase regime, up to and including super-heated steam and may include coolant flow reversal. The code has an optional "voiding model" which estimates the voiding produced by sub-cooled boiling.

6. RESTRICTIONS OR LIMITATIONS

The PARET model is subject to several recognized limitations which may limit the applicability to certain specific problems, depending on the nature of the transient under consideration. The code employs steady-state heat transfer correlations which may prove unrealistic in certain transient situations. Any complete description of a severe transient must include provisions for some sort of thermal or hydraulic crisis. PARET is limited in predicting such crises by the fact that it employs only steady-state correlations (no transient correlations with demonstrated reliability have been developed). Accurate descriptions of hydraulic instability depend upon accurate computation of transient pressure and flow fluctuations. PARET employs an incompressible model and a simplified void volume generation model with a homogeneous fluid. Also, the magnitude of local pressures predicted to accompany coolant expulsion is strongly affected by the number of axial sections chosen. The hydrodynamic output thus should be interpreted as a qualitative indication of a possible crisis rather than a reliable quantitative prediction. PARET is not applicable to either destructive excursions or situations in which there are space-time variations in the neutron flux.

7. TYPICAL RUNNING TIME

Variable.

8. COMPUTER HARDWARE REQUIREMENTS

The code runs on workstations or personal computers.

9. COMPUTER SOFTWARE REQUIREMENTS

An executable created with a Lahey Fortran 95 compiler is included with the Windows version of PARET-ANL, and a Linux executable created using GNU77 2.96 is included with the Unix/Linux version. A Fortran compiler is required for program compilation on Unix machines. PARET-ANL was tested at RSICC on a Pentium III 650 machine running Windows 2000, a Sun UltraSparc 60 running SunOS 5.6 with gnu77 5.23, and a Dell PowerEdge 2300 running Redhat Linux Version 7.0 with gnu77 2.96.

10. REFERENCES

a. included in documentation:

W. L. Woodruff and R. S. Smith, "A Users Guide for the ANL Version of the PARET Code, PARET/ANL (2001 Rev.)," ANL/RERTR/TM- 16 (March 2001).

b. background references:

C. F. Obenchain, "PARET - A Program for the Analysis of Reactor Transients," IDO-17282 (January 1969).

W. L. Woodruff, "A Kinetics and Thermal-hydraulics Capability for the Analysis of Research Reactors," Nucl. Tech., 64 (February 1984).

11. CONTENTS OF CODE PACKAGE

The package includes the referenced document in 10.a and a CD with a self-extracting compressed Windows file and a GNU compressed tar file that includes Fortran source files and test cases. PC and LINUX executables are also included.

12. DATE OF ABSTRACT

February 2002.

KEYWORDS: HEAT TRANSFER; REACTOR SAFETY; THERMAL HYDRAULICS; MICROCOMPUTER; WORKSTATION