**1. NAME AND TITLE**

OZMA: Calculation of Resonance Reaction Rates in Reactor Lattices Using Resonance Profile
Tabulations.

**AUXILIARY ROUTINE**

HAMMER LIBRARY: A program to convert library from binary to formatted form.

**2. CONTRIBUTOR**

Technion, Israel Institute of Technology, Haifa, Israel.

**3. CODING LANGUAGE AND COMPUTER**

Fortran IV; IBM 370/3033 (C00406I037000).

**4. NATURE OF PROBLEM SOLVED**

The OZMA code solves the neutron transport equation for a reactor lattice unit cell at energies which lie in the resolved resonance regions of the lattice nuclides. Spherical, slab, cylindrical, square and hexagonal geometries can be handled.

OZMA is most readily applied as a sophisticated resonance module for the HAMMER lattice code.
It is more flexible and more accurate than the resonance treatments provided in HAMMER itself in the
resolved resonance region. In particular, mixtures of numerous resonance nuclides can be handled
simultaneously rather than by individual resonance treatments. The results obtained by OZMA can
also be used as reference values against which simpler resonance treatments can be checked.

**5. METHOD OF SOLUTION**

OZMA combines the very detailed procedure needed for producing the fine structure energy spectrum of the neutron flux (so that all flux depressions in the resonances become apparent with sufficient accuracy) with an analysis of the spatial variation of the neutron flux and energy spectrum and, if desired, even the angular distribution of the flux. For the latter, the scattering anisotropy may be taken into account in the laboratory system. OZMA enables the user to decide what mesh sizes are to be used for the energy, spatial, and directional coordinates, so that one of these can be stressed more than another consistent with overall storage requirements.

The transport calculations solve either the integral transport equation for the scalar flux or the discrete ordinates form of the integro-differential transport equation for the directional flux density. Slowing down sources for elastic scattering are evaluated by rapid numerical integration techniques which proceed from one lethargy mesh point to the next by means of recursion formulae. They have been coded for the isotropic and linearly anisotropic source components, and can be extended to higher orders of scattering by suitable coding changes. An upscattering correction for hydrogen in the low epithermal region is available.

OZMA does not make direct use of resonance parameters, but is based on preprocessing these into Doppler-broadened cross-section tables to enable following the resonance shapes throughout the resolved resonance region. From these tables, the cross sections of the nuclide mixtures contained in the different subregions of the lattice unit cell can be readily derived at all energies needed for the resonance calculations.

A new methodology was developed for solving the point-energy integral or discrete ordinates
transport equations on a dense energy grid as required to handle resonance profiles. The resulting
spatially-dependent flux spectrum provides the resonance reaction rates needed for subsequent complete
lattice analysis.

**6. RESTRICTIONS OR LIMITATIONS**

None noted.

**7. TYPICAL RUNNING TIME**

No study has been made by RSIC of typical running times for OZMA.

**8. COMPUTER HARDWARE REQUIREMENTS**

OZMA is operable on the IBM 370/3033 computers. The code requires 344 K of storage.

**9. COMPUTER SOFTWARE REQUIREMENTS**

A Fortran G compiler is required.

**10. REFERENCES**

J. Barhen and W. Rothenstein, "OZMA A Code to Calculate Resonance Reaction Rates in Reactor Lattices using Resonance Profile Tabulations," EPRI-NP-926 (February 1981).

J. Barhen, W. Rothenstein, and E. Taviv, "The HAMMER Code System," (Sections 3 & 4) EPRI-NP-565 (October 1978).

**11. CONTENTS OF CODE PACKAGE**

Included are the referenced documents and three (1.44 MB) diskettes in self-extracting compressed
DOS files which contain the source codes plus sample problem input and output.

**12. DATE OF ABSTRACT**

February 1982.

**KEYWORDS: ** NEUTRON; DISCRETE ORDINATES; INTEGRAL BOLTZMANN EQUATION; LWR; MULTIGROUP; CELL CALCULATION