Modelling of Off-Site Radiological Dose Consequences from an Accidental Airborne Release at the Susquehanna Steam Electric Station

The Susquehanna Terrain-incorporating Regional Effluent Assessment Model (STREAM) has been available since 1985 to provide off-site dose projections in the event of the accidental airborne release of radioactive material from the Susquehanna Steam Electric Station (SSES). In STREAM, meteorological data and forecasts are obtained from measurements at the SSES's on-site and off-site monitoring stations and from the National Weather Service. Atmospheric dispersion is modelled using the MESOI Lagrangian puff model and a straight-line plume model. Dispersion modelling results, monitored and estimated release data, and dose factor information are used in STREAM's dose assessment modelling. To facilitate analyses, input data and model output products can be displayed graphically or numerically. Modelling results are coupled with available field monitoring data to assist emergency response personnel in developing protective action recommendations. The performance of STREAM will be evaluated during a federal field exercise and during a series of atmospheric tracer studies that will be conducted at the SSES in 1993. Results of these and other evaluations will be used to guide a planned upgrade of the STREAM system.