RSICC CODE PACKAGE PSR-419

1. NAME AND TITLE

COBRA4I: Code System to Calculate Rod-Bundle and Core Thermal-Hydraulics.

2. CONTRIBUTORS

Pacific Northwest Laboratory, Richland, Washington,

Century Research Center Corp, Tokyo, Japan and

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

3. CODING LANGUAGE AND COMPUTER

FORTRAN IV; CDC7600; CRAY, IBM360 (P00419MNYCP00).

4. NATURE OF PROBLEM SOLVED

COBRA4I performs steady-state and transient thermal-hydraulic analysis of rod bundle nuclear fuel elements and cores via the subchannel analysis method.

5. METHOD OF SOLUTION

The conservation equation of flow and energy are solved for interconnected subchannel control volumes via conventional finite differencing techniques. The steady-state calculations are solved by implicit finite differencing whereas the transient calculations are performed by either an implicit or explicit finite difference scheme. Internal rod temperatures are calculated by an orthogonal allocation approximation to the heat conduction equation.

6. RESTRICTIONS OR LIMITATIONS

Using the COBRA4I code option to store variables on peripheral storage devices eliminates any practical limit as to maximum problem size. However, computer core requirements and code execution time varies.

7. TYPICAL RUNNING TIME

On a CDC7600 running time is 0.004 seconds per cell-iteration using the implicit solution scheme and 0.00006 seconds per cell-iteration using the explicit scheme.

8. COMPUTER HARDWARE REQUIREMENTS

CDC, CRAY &IBM360 versions are included. On CDC 202,000 (octal) words and 4 scratch units besides the standard input/output units are required.

9. COMPUTER SOFTWARE REQUIREMENTS

CDC-SCOPE; CRAY-COS; IBM360-MVS.

10. REFERENCES

a) Included in documentation:

C. L. Wheeler, C. W. Stewart, R. J. Cena, D. S. Rowe, A .M. Sutey, "COBRA-IV-I: An Interim Version of COBRA for Thermal-Hydraulic Analysis of Rod Bundle Nuclear Fuel Elements and Cores," BNWL-1962 (March 1976).

C. W. Stewart, C. L. Wheeler, R. J. Cena, C. A. McMonagle, J. M. Cuta, D. S. Trent, "COBRA-IV: The Model and the Method," BNWL-2214 (July 1977).

C. W. Stewart, C. A. McMonagle, M. J. Thurgood, T. L. George, D. S. Trent, J. M. Cuta, G. D. Seybold, "Core Thermal Model: COBRA-IV Development and Applications," BNWL-2212 (January 1977).

b) Background information:

D. M. Lister, P. A. Jallouk, "COBRA IV-I An IBM-Compatible Version," NUREG/CR-0519, ORNL/NUREG/CSD-9 (December 1978).

11. CONTENTS OF CODE PACKAGE

Included in the package are the referenced documents in (10.a) and a 3.5" diskette containing self-extracting DOS files, which include source, test cases and job control language. Executables are not included.

12. DATE OF ABSTRACT

July 1999.

KEYWORDS: HEAT TRANSFER; THERMAL HYDRAULICS