**RSICC CODE PACKAGE PSR-495**

**1. NAME AND TITLE**

TRIGLAV: Code System to Calculate Mixed Cores in TRIGA Mark II Research Reactor.

**2. CONTRIBUTORS**

Jozef Stefan Institute, Ljubljana, Solvenia, through the OECD Nuclear Energy Agency Data Bank, Issy-Les Molineaux, France.

**3. CODING LANGUAGE AND COMPUTER**

Fortran 77; PC (P00495/PC586/00).

**4. NATURE OF PROBLEM SOLVED**

TRIGLAV is a computer program for reactor calculations of mixed cores in a TRIGA Mark II research reactor. It can be applied for fuel element burn-up calculations, for power and flux distributions calculations and for reactivity predictions. The TRIGLAV program requires the WIMS-D4 program with the original WIMS cross-section library extended for TRIGA reactor specific nuclides. This package includes the code TRIGAC, which is a new version of TRIGAP.

**5. METHOD OF SOLUTION**

TRIGLAV is based on four group time independent diffusion equations in two dimensional cylindrical (r, theta) geometry. The diffusion equation is solved using finite differences method with iteration of fission density. The group constants are calculated for every unit cell independent of: fuel or non-fuel element geometry, material composition, actual fuel element burnup, temperature, water temperature and density, cladding temperature and xenon concentration.

**6. RESTRICTIONS OR LIMITATIONS**

None noted.

**7. TYPICAL RUNNING TIME**

The sample problems took <20 minutes on a Pentium III 650MHz PC.

**8. COMPUTER HARDWARE REQUIREMENTS**

IBM PC and compatibles.

**9. COMPUTER SOFTWARE REQUIREMENTS**

TRIGLAV runs under the MS-DOS and LINUX operating systems. The included PC executables in the TRIGLAV\CODE directory were created with Lahey F77L3-EM/32 Version 5.1. The included PC TRIGAC executable was created at NEA with Lahey Fortran 77 Version 5.2 on a PC Pentium III 500.

**10. REFERENCES**

A. Persic, M. Ravnik, S. Slavic and T. Zagar, "TRIGLAV, A Program Package for Research Reactor Calculations," IJS-DP-7862, Version 1 (March 28, 2000).

I. Mele, M. Ravnik, "TRIAC - A New Version of TRIGAP Code," IJS-DP-6242 (March 2000).

**11. CONTENTS OF CODE PACKAGE**

Included in the package are the reference documents and a CD which contains a self-extracting Windows file with the source codes, sample problems and PC executables.

**12. DATE OF ABSTRACT**

August 2001.

** KEYWORDS:** BURNUP; CYLINDRICAL GEOMETRY; DIFFUSION
THEORY