** **

**1. NAME AND TITLE**

RICM: Resonance Absorption in Multi-Region Slab or Square or Hexagonal Lattice.

**2. CONTRIBUTOR**

Japan
Atomic Energy Research Institute through the OECD Nuclear Energy Agency Data
Bank, Issy-les-Moulineaux, France.

**3. CODING LANGUAGE
AND COMPUTER**

Fortran, IBM 360 Series (P00600I036000).

**4. NATURE OF
PROBLEM SOLVED**

RICM calculates the resonance absorption integral of resonant isotope in a multi-region lattice using the first flight collision probability. The lattice configurations considered are a slab lattice, a square or hexagonal lattice and a cylindricalized lattice with isotropic or perfect reflecting boundary condition. Cases for an isolated rod or plate and homogeneous system can also be treated.

**5. METHOD OF
SOLUTION**

Slowing down of neutrons by each isotope in each region is solved by either exact numerical integration of the slowing down equation or narrow - or wide-resonance approximation. Breit-Wigner's single level formula is used for the resonance cross section and Porter-Thomas distribution of neutron width is taken into account in the unresolved region.

**6. RESTRICTIONS OR
LIMITATIONS**

Maximum number of regions 5; Maximum number of groups 100.

**7. TYPICAL RUNNING
TIME**

For the calculation of 3 regions 54 groups - about 3.2 minutes on IBM 360/65.

**8. COMPUTER
HARDWARE REQUIREMENTS**

IBM 360 /65 (32k words 2 library tape units.)

**9. COMPUTER
SOFTWARE REQUIREMENTS**

IBM 3760 Operating System.

**10. REFERENCES**

**a) Included Documentation:**

H. Mizuta, K. Aoyama, Y.Fukai, “RICM - An IBM 7090 Code of Resonance Integral Calculation for Multi-Region,” JAERI-1134 (1967).

**11. CONTENTS OF CODE
PACKAGE**

The package is distributed on a CD with a compressed zip file including source files, documentation, sample input and output.

**12. DATE OF ABSTRACT**

December 2013.

**KEYWORDS: **BREIT-WIGNER
FORMULA, COLLISIONS, PORTER-THOMAS DISTRIBUTION, PROBABILITY, REACTOR LATTICES,
REASONANCE ABSORPTION, SLOWING