1. NAME AND TITLE

PATCH-7: Three-Dimensional Kernel Integration CodeExplicit Single Scattering Option.

2. CONTRIBUTORS

Radiation Physics Incorporated, Huntington Beach, California.

McDonnell Douglas Astronautics Company, Huntington Beach, California.

3. CODING LANGUAGE AND COMPUTER

FORTRAN IV; CDC CYBER-74.

4. NATURE OF PROBLEM SOLVED

PATCH-7 calculates neutron and gamma-ray intensities in 3-dimensional quadratic surface geometric systems using the point kernel method. Source systems can be described as axially symmetric cylindrical volume sources or point sources; radiation levels can be determined by integrating point kernel functions over source volumes or by interpolating flux data input in an (R,phi) grid. Flux contributions from capture and scattering events, due to interactions of primary radiation with materials in any region of the geometric system, can be calculated. Radiation contributions can be tallied according to the source system from which they were emitted and also according to the regions traversed on primary and secondary legs from source to detector. The latter data provide information required to optimize the mass distribution of shielding materials. A capability to optimize a conical shadow shield is included in the program; more sophisticated optimization analyses require use of the region-wise transmission data in a separate optimization computation such as described in the reference.

5. METHOD OF SOLUTION

Geometry calculations use an early version of the CCC-48/QAD geometry package used in the CCC-168/FASTER, CCC-118/SIGMA, and CCC-240/CAMERA codes. Neutron attenuation uses a modified Albert-Welton kernel with buildup, the buildup factor being dependent on hydrogeneous areal density and asymptoting at a value of 25. Gamma-ray attenuation is exponential with buildup. Neutron scattering distributions are evaluated as isotropic except for hydrogen (which is isotropic in the center-of-mass system). Gamma-ray scattering is evaluated from the Klein-Nishina relationships. Secondary gamma sources are evaluated from computed neutron fluxes and cross section data provided as input. Integrations over source volumes, for both primary and secondary sources, use a differential spherical volume element with non-linear spacing along the path through the source volume.

The tallying of detector contributions by transmission paths or zones can be quite precise. Up to three regions can be specified for each zone, each of which must be traversed by either the primary or secondary log of the transmission path in order for the incremental contribution to be tallied in the zone. All contributions not tallied in an input-specified zone are sorted into a single overflow zone.

6. RESTRICTIONS OR LIMITATIONS

Restrictions on problem size are set by dimension statements and hence are easily changed to accommodate different types of problems. Current limits are: 5 secondary source spectra, 8 response functions, 40 materials, 40 elements, 5 gamma groups, 100 surfaces, 100 regions, 5 volume source systems, 15 point source systems comprised of 75 individual point sources, 15 secondary or scatter source regions, 20 transmission zones of up to 3 regions each, and 50 detector locations.

7. TYPICAL RUNNING TIME

Running times are roughly proportional to the product of number of regions, number of primary sources, number of secondary sources, and number of detectors. Times are very dependent on type of sources (volume, point, flux table interpolation) and requested integration grid for both primary and secondary source volumes.

8. COMPUTER HARDWARE REQUIREMENTS

PATCH-7 is operable on a CDC 6500 computer with 400 K octal core. It should be operable, with minor modifications, on most machines using FORTRAN IV with 200 K octal core. It requires no auxiliary storage devices, nor any output devices other than a printer.

9. COMPUTER SOFTWARE REQUIREMENTS

A FORTRAN IV compiler and a standard SCOPE operating system are required.

10. REFERENCE

M. P. Billings, "An Effective Multiple-Constraint Shield Optimization Technique," MDAC Paper WD-1944 (September 1972).

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.

12. DATE OF ABSTRACT

May 1974; updated August 1975.