The concentrations of radionuclides in air at the selected offsite and onsite locations around the INEL were estimated using the CALPUFF modeling system. CALPUFF is a non-steady-state air quality modeling system developed by Sigma Research Corporation (now part of Earth Tech, Inc., of Concord, Massachusetts). The original development of the CALMET/CALPUFF models was sponsored by the California Air Resources Board and is now supported by the U.S. Environmental Protection Agency.

Local meteorological data collected at INEL and surrounding area during the years of release were used as an input to the calculations. To test the validity of estimates of airborne concentrations of radionuclides, CALPUFF was evaluated using data collected in 1999 as part of an atmospheric sulfur hexafluoride (SF6) tracer experiment. Model testing indicated that CALPUFF reproduced satisfactorily time-averaged measured concentrations.

Concentrations in air were estimated on an hourly basis and summarized as monthly averages for all major communities within a 50-mile radius of the Idaho Chemical Processing Plant. The uncertainties in the estimated concentrations in air were quantified by accounting for uncertainty in the wind field, emission rates of radionuclides and vertical wind profiles, terrain adjustment methods, and atmospheric dispersion coefficients.

The analysis of the atmospheric dispersion of radionuclides released from the ICPP is presented in the following report:

Atmospheric Dispersion Report

Principal authors:
Zivorad Radonjic, SENES Consultants Limited, Canada
Ron Stager, SENES Consultants Limited, Canada
A. Iulian Apostoaei, SENES Oak Ridge, Inc.