1. NAME AND TITLE

TRIGAP: A Computer Code for TRIGA Type Reactors.

2. CONTRIBUTOR

Jozef Stefan Institute, Ljubljana, Yugoslavia through the International Atomic Energy Agency, Vienna and the NEA Data Bank, Gif-sur-Yvette, France

3. CODING LANGUAGE AND COMPUTER

FORTRAN 77; IBM PC.

4. NATURE OF PROBLEM SOLVED

TRIGAP was developed for reactor physics calculations of the 250 kW TRIGA reactor. The program can be used for criticality predictions, power peaking predictions, fuel element burn-up calculations and data logging, and in-core fuel management and fuel utilization improvement.

5. METHOD OF SOLUTION

The program solves the one-dimensional, two-group diffusion equation using the finite- difference method.

6. RESTRICTIONS OR LIMITATIONS

Expected accuracy of the calculations is 1.5% absolute and 0.5% for relative criticality, 15% for power distributions and peakings and 10% for fuel element burnup.

7. TYPICAL RUNNING TIME

The sample problem only took about 1/2 minute on a PC/AT and a few seconds on a PC-486.

8. COMPUTER HARDWARE REQUIREMENTS

TRIGAP runs on the IBM PC with at least 540kb of memory.

9. COMPUTER SOFTWARE REQUIREMENTS

The code was written in FORTRAN 77 and was tested using the Microsoft Version 5.0 compiler.

10. REFERENCES

I. Mele, S. Slavic, and M. Ravink, "Burnup Calculation of TRIGA Fuel Elements - Calculation of Radionuclide Inventories of TRIGA Fuels," IJS-DP-5883 (September 1990).

M. Ravnik, I. Mele, S. Slavic, and B. Zefran, "Development of Computer Programs for Research Reactor Calculations Using Small Computers," IJS-DP-5040 (1987).

I. Mele and M. Ravink, "TRIGAP - A Computer Programme for Research Reactor Calculations IBM.PC. Version," IJS-DP-4238 (December 1985).

11. CONTENTS OF CODE PACKAGE

Included are the referenced documents and a 5.25-in. DS/HD (1.2MB) diskette which includes source codes, sample input and output.

12. DATE OF ABSTRACT

April 1992.

KEYWORDS: BURNUP; CRITICALITY CALCULATIONS;