NEA-0513 IRESINT-3.

1. NAME OR DESIGNATION OF PROGRAM:  IRESINT-3.

3. NATURE OF PHYSICAL PROBLEM SOLVED

IREDINT-3 computes the resonance  absorption of neutrons in a square or hexagonal lattice of infinitely long clad fuel rods. The resonances are described in the  single-level Breit-Wigner formalism. L-factors for form are computed if desired. Resonance overlap may be taken into account.
The rods may be grouped into fuel elements separated by gaps. The resolved resonances are treated in the IR or NR approximations. Six  different versions of the IR approximation are available with provisions for using different approximations for different resonances. In the unresolved range, only the NR approximation can be used.

4. METHOD OF SOLUTION

The Dancoff correction is calculated by numerical integration or by the Sauer-Bonalumi method. The IR parameter equations are solved iteratively. The integral J is interpolated from tables and an analytical correction for interference scattering is applied.

5. RESTRICTIONS ON THE COMPLEXITY OF THE PROBLEM

Up to 5 absorbers, 2  admixed moderators, 1 cladding nuclide and 3 external moderators may be present. No more than 250 resonances per absorber are permitted,  but an absorber with more than 250 resonances can be treated as two  or more absorbers. There are some other restrictions, but they are unlikely to be of any importance. Slight numerical difficulties may  be encountered for fast reactor lattices. For thick fuel rods (diameter appreciably above 1 cm), the accuracy may be poor due to the flat flux approximation used in the calculation of escape probabilities.

6. TYPICAL RUNNING TIME:  Less than 30 seconds.

7. UNUSUAL FEATURES OF THE PROGRAM

IRESINT-3 uses free-form input.
Default values are available for most of the input, so that a very brief input is often sufficient. On the other hand, a wide range of  options is available, giving the user great freedom to choose between accuracy and speed.

8. RELATED AND AUXILIARY PROGRAMS

IRESINT-2 has been superseded by IRESINT-3. ETOI prepares a resonance parameter library for IRESINT-3 from ENDF/B data.

10. REFERENCES

- Aero Patrakka:
  ETOI, A Program to Process Resonance Data from ENDF/B to IRESINT-3        Technical Research Centre of Finland, Nuclear Engineering Laboratory, Memo 9/1974, 12+1+7 pp.

- Randolph Hoglund and Frej Wasastjerna:
  IRESINT-3, A FORTRAN Program for Computation of Resonance
  Integrals
  Technical Research Centre of Finland, Nuclear Engineering
  Laboratory, Report 16, 147 pp. (January 1975).

11. MACHINE REQUIREMENTS

53000 words of core storage and drum, disc or  tape storage for 0-3 files depending on the problem. A clock is used but is not essential.

13. OPERATING SYSTEM OR MONITOR UNDER WHICH PROGRAM IS EXECUTED:  Standard EXEC 8.

14. ANY OTHER PROGRAMMING OR OPERATING INFORMATION OR RESTRICTIONS

The fast I/O routine NTRAN, provided in the FORTRAN V library, is used for the resonance parameter library and scratch file. Complete information on which statements must be changed, if NTRAN cannot be  used, is available.

15. NAME AND ESTABLISHMENT OF AUTHOR

      Frej Wasastjerna
      Nuclear Engineering Laboratory
      Technical Research Centre of Finland
      Lonnrotinkatu 37
      SF-00180 Helsinki 18
      Finland

File name	File description	Records
NEA0513_01.001	SOURCE (F5 AND ASSEMBLER)	5058
NEA0513_01.002	SAMPLE PROBLEM INPUT CASE1	36
NEA0513_01.003	SAMPLE PROBLEM OUTPUT CASE1	522
NEA0513_01.004	SAMPLE PROBLEM INPUT CASE2	36
NEA0513_01.005	SAMPLE PROBLEM OUTPUT CASE2	2538
NEA0513_01.006	JCL ,SEGMENTATION AND INFORMATION	142