SKYCONES evaluates the skyshine doses produced by a point neutron or gamma-photon source emitting, into the atmosphere, radiation that is collimated into an upward conical annulus between two arbitrary polar angles. The source is assumed to be axially (azimuthally) symmetric about a vertical axis through the source and can have an arbitrary polyenergetic spectrum. Nested contiguous annular cones can thus be used to represent the energy and polar-angle dependence of a skyshine source emitting radiation into the atmosphere. The calculation of the skyshine doses uses the integral line-beam method which is based on a three-parameter approximation of the neutron and gamma-ray line-beam response functions.

Source neutron energies must be between 0.01 and 14 MeV. For energies above 1 MeV, source-to-detector distances can be as great as 2500 m. For source energies below 1 MeV, the maximum source-to-detector distance is somewhat less. For gamma photons, the maximum source-to-detector distance is 3000 m for photon energies between 0.02 and 10 MeV and 1500 m for photon energies between 10 and 100 MeV. For neutron sources, both the neutron skyshine dose and the secondary photon dose from neutron interactions in the air are computed separately.

The neutron skyshine doses are expressed in units of dose equivalents (Sv) per source neutron based on one of the following three response functions: (1) the effective dose equivalent for AP irradiation of an anthropomorphic phantom, (2) the dose equivalent at 10 mm into the ICRU sphere for isotropic (ISO) irradiation, and (3) the ambient dose equivalent on the principal axis at 10 mm depth for irradiation of the ICRU sphere by a plane parallel beam (PAR). Gamma-photon skyshine doses are expressed in terms of air-absorbed dose (Gy) and roentgens.

For a user's mannual, see the report by J.K. Shultis, SKYCONES: A Code for Neutron and Photon Skyshine Calculations from Annular Conical Sources, Report 9903, Institute for Computational Research in Engineering and Scinece, Kansas State University, Manhattan, KS, June 1999. This report, in PostScript and Adobe PDF format, is provided in the distribution package available from this site.

Current version is 1.1, released June 27, 1999.