1. NAME AND TITLE

MACK-IV: Calculation of Nuclear Response Functions from Nuclear Data in ENDF Format.

MACK-IV is an expanded version of PSR-52/MACK.

2. CONTRIBUTORS

Argonne National Laboratory, Argonne, Illinois.

Oak Ridge National Laboratory, Oak Ridge, Tennessee.

3. CODING LANGUAGE AND COMPUTER

Fortran IV; IBM 360/370.

4. NATURE OF PROBLEM SOLVED

MACK-IV calculates nuclear response functions important to the neutronics analysis of nuclear and fusion systems. A central part of MACK-IV deals with the calculation of the nuclear response function for nuclear heating more commonly known as the kerma factor. Pointwise and multigroup neutron kerma factors, individual reactions, helium, hydrogen, and tritium production response functions are calculated from any basic nuclear data file in ENDF/B format. MACK-IV processes all reactions in the energy range of 0 to 20 MeV for fissionable and nonfissionable materials. It also calculates the gamma production cross sections and the gamma production energy matrix.

A built-in computational capability permits MACK-IV to calculate the cross sections in the resolved and unresolved resonance regions from resonance parameters in ENDF/B with an option for Doppler broadening. All energy pointwise and multigroup data calculated by the code can be punched, printed and/or written on tape files. Multigroup response functions (e.g., kerma factors, reaction cross sections, gas production, atomic displacements, etc.) can be output in the format of ``MACK-ACTIVITY-Table'' suitable for direct use with current neutron (and photon) transport codes.

5. METHOD OF SOLUTION

The neutron kerma factor, whose calculation is a central part of MACK-IV, is obtained by summing over all possible neutron reactions, the product of the reaction cross section and the energy deposited in the reaction within a negligible distance from the site of collision. The energy deposited in a reaction is the sum of the kinetic energies imparted to the recoil nucleus and charged particles emitted. This is calculated from an energy balance that accounts for mass-to-energy conversion and the energies carried away from the site of collision by neutrons and secondary gamma rays. The kinetic energy of the neutrons is calculated from the angular or the energy distributions given in ENDF/B data files. The part of the reaction energy carried away with the gamma rays is calculated by one of two methods that can be selected by the user. In the first method, the gamma energy is calculated directly from information in the gamma production files of ENDF/B. In the second method, the gamma energy is deduced from solving all the nuclear kinematics equations (momentum as well as energy balance) assuming that direct information on gamma-production is not available. The calculation of cross sections in the resonance region follows that of the NPTXS module in the AMPX system. Multigroup kerma factors and cross sections are calculated using an arbitrary weighting function. The gamma production cross sections are calculated from the gamma production files in ENDF/B. MACK-IV ensures the consistency in preserving the energy in all phases of the nuclear heating calculations.

6. RESTRICTIONS OR LIMITATIONS

The main restriction is the availability of computer core storage. MACK-IV utilizes the dynamic storage technique to save on core storage requirements.

7. TYPICAL RUNNING TIME

The problem run time depends mainly on a) the number of resolved resonances, b) the size of the pointwise energy mesh, c) the method selected for calculating kerma factor, and d) the number of neutron and gamma energy groups. Typical CPU time on an IBM-370/195 computer is 1-3 min for non resonance nuclides and 5-10 min for resonance nuclides with 1000 energy points, 171 neutron groups, and 36 gamma energy groups.

8. COMPUTER HARDWARE REQUIREMENTS

MACK-IV is operable on the IBM 360/370 computers. It is also compatible with the UNIVAC-1110 and with the CDC-7600 with minor modifications. The central memory storage requirements vary but are typically within 400 to 800 K bytes. The input/output and temporary files vary from 4 to 13 depending on the problem.

9. COMPUTER SOFTWARE REQUIREMENTS

A Fortran IV compiler is required.

10. REFERENCE

M. A. Abdou, Y. Gohar, and R. Q. Wright, "MACK-IV, A New Version of MACK: A Program to Calculate Nuclear Response Functions from Data in ENDF/B Format," ANL/FPP-77-5 (July 1978).

11. CONTENTS OF CODE PACKAGE

Included are the referenced document and one (1.2MB) DOS diskette which contains the source code and sample problem input and output, and ENDF/B-IV data for Li-7, C, and Be-9.

12. DATE OF ABSTRACT

March 1984.