Models Used in Relating Exposures to Estimated Consequences

DOE-STD-6003-96

The RSAC (Wenzel 1993) code calculates the consequences of the release of radio-

nuclides to the atmosphere. A user can generate a radioactive inventory, decay and ingrow the

inventory during transport through process facilities and the environment, model the downwind

dispersion of the activity, and calculate doses to downwind individuals. Doses are calculated

through the inhalation, immersion, ground surface, and ingestion pathways.

The CAP-88 (Clean Air Act Assessment Package-1988) (Parks 1992) computer model is

a set of computer programs, data bases, and associated utility programs for estimation of dose

and risk from routine radionuclide emissions to air. CAP-88 must be used to show compliance

with 40 CFR 61.93(a) unless the EPA approves an alternate.

The CAP-88-PC software package allows users to perform full-featured dose and risk

assessments in a personal computer environment for the purpose of demonstrating compliance

with 40 CFR 61.93(a) for routine radionuclide releases to the air. CAP-88-PC provides the

CAP-88 methodology for assessments of both collective populations and MEIs. The complete

set of dose and risk factors used in CAP-88 is provided. CAP-88-PC used a modified Gaussian

plume equation to estimate the average dispersion of radionuclides released from up to six

sources. The sources may be either elevated stacks, such as a smokestack, or uniform area

sources, such as a pile of uranium mill tailings. Plume rise can be calculated assuming either a

momentum or buoyancy-driven plume. Assessments are done for a circular grid of distances

and directions for a radius of 80 km (50 miles) around the facility.