RSICC CODE PACKAGE CCC-669

1. NAME AND TITLE

RETRANS: Code for Calculating Reactivity Transients in a LWR.

Previous Versions Available: RETRANS (C669 IBM 3084, SIEMENS 7-541)

2. CONTRIBUTORS

Institut fur Reaktorsicherheit, Vienna, Austria, through the Nuclear Energy Agency Data Bank, Gif-sur-Yvette, France.

3. CODING LANGUAGE AND COMPUTER

FORTRAN 77; SUN SPARC 60 (C00669/SUN05/00).

4. NATURE OF PROBLEM SOLVED

RETRANS is appropriate to calculate power excursions in light water reactors initiated by reactivity insertions due to withdrawal of control elements. The neutron physical model is based on the time-dependent two-group neutron diffusion equations. The equation of state of the coolant is approximated by a table built into the code. RETRANS solves the heat conduction equation and calculates the heat transfer coefficient for representative fuel rods at each time-step.

5. METHOD OF SOLUTION

The time-dependent neutron diffusion equations are modified by an exponential transformation and solved by means of a finite difference method. There is an option accelerating the inner iterations of the difference scheme by a coarse-mesh rebalancing method. The heat balance equations of the thermohydraulic model are discretized and converted into a tridiagonal system of linear equations which is solved recursively.

6. RESTRICTIONS OR LIMITATIONS

Modeling is limited to R-Z geometry and one-phase-flow.

7. TYPICAL RUNNING TIME

The sample problem executed in less than 30 seconds on a SUN SPARC 60 with 128 MB RAM running SUN OS 5.6 (Solaris 2.6).

8. COMPUTER HARDWARE REQUIREMENTS

RETRANS runs on a SUN SPARC 60.

9. COMPUTER SOFTWARE REQUIREMENTS

RETRANS was tested at RSICC under the Sun OS 5.6 (Solaris 2.6) operating system with the f77 FORTRAN compiler version 4.2.

10. REFERENCE

G. Kamelander, "RETRANS - A Program for Calculating Reactivity Transients," Computer Physics Communications 38, CPC00507 (May 1985).

11. CONTENTS OF CODE PACKAGE

Included are the referenced document and one 3.5" DOS diskette with source and sample problem in a UNIX tar file.

12. DATE OF ABSTRACT

March 1999.

KEYWORDS: NEUTRON; DIFFUSION THEORY