4. METHOD OF SOLUTION
QADMOD-G calculates gamma-ray fluxes, dose rates, or heating rates at discrete locations within a complex source-geometry configuration by representing a volume-distributed source by a number of point isotropic sources and computing the distances through all regions traversed by the line-of-sight from the source points to a desired receiver point. From these distances and the characteristics of the materials within them, energy- dependent exponential attenuation factors and energy-dependent buildup factors for gamma-rays are applied to calculate the direct gamma-ray dose and the gamma-ray dose with buildup. The responses to individual source points are summed into source-energy groups and recorded. Input data consists of the source distribution and intensity, the physical geometry, and may include tabulations of attenuation coefficients, buildup factor coefficients, and conversion factors.
Each source may be represented by a volume-distributed source or a series of up to 27 000 point sources. The source spectra are assumed to be constant for all volumes. The source may be defined in terms of a cylindrical, a Cartesian, or a spherical-geometry coordinate system.
As many as 500 point isotropic sources defined in terms of a spatial position and power density may be used in point source calculations. Each point source is represented by the same specified energy spectrum.
Shield configurations are represented in terms of a three- dimensional model which is made up of a series of material and void regions. Each region is defined by a previously-described set of surfaces.