Validation of the AIRDOS-EPA computer code by simulating intermediate range transport of 85Kr from the Savannah River Plant

The AIRDOS-EPA computer code estimates the annual doses to the general public resulting from releases of radionuclides to the atmosphere. It has been chosen by the U.S. Environmental Protection Agency for setting radionuclide emission standards for U.S. nuclear facilities. This code uses a modified Gaussian plume equation to estimate air concentrations resulting from the release of a maximum of 36 radionuclides. Radionuclide concentrations in food products are estimated from the output of the atmospheric transport model using a terrestrial transport model. One year of weekly average 85Kr concentrations observed at 13 stations located 30-150 km distant from a point source at the Savannah River Plant, Aiken, South Carolina, have been used in a validation study of the atmospheric transport portion of AIRDOS-EPA. The predicted annual average concentration exceeded the observed value at each station. The overprediction factor ranged from 1.4 to 3.4. Pearson's correlation between pairs of logarithms of observed and predicted values was r = 0.93. As the averaging time of the prediction decreases, however, the uncertainty in the prediction increases. (author)