ANS 2.15

Abstract

<strong>Introduction and scope</strong> <br>In the decades prior to this standard, significant enhancements have been made in the area of atmospheric dispersion modeling. Considerable advances have occurred in our understanding of atmospheric processes that play a key role in the transport, dispersion, and deposition of atmospheric contaminants. In addition, dramatic advances in computer technologies have resulted in a significant increase in computational processing speeds and capabilities. Calculations that would have taken days or weeks of computation resources on a mainframe computer can now be completed in minutes on an inexpensive personal computer. Graphical displays of information that required hand drawing by graphics specialists are now available through the use of geographical information system ~GIS! software. <br>In addition to the advances in modeling, technological advances have occurred in the areas of meteorological monitoring and data sharing. New digital instrumentation allows for the measurement of atmospheric parameters that were not previously measurable on a routine and widespread basis e.g., direct measurements of turbulence!. Remote monitoring, satellite measurements, and numerical modeling of meteorological parameters provide new suites of data for atmospheric dispersion modeling. More data are available in real time or close to real time from meteorological monitoring stations that were not accessible in the past. Radiotelemetry, cellular networks, and the Internet provide routine access to new sources of data. <br>The purpose of this document is thus to establish criteria for evaluating the atmospheric effects of routine radioactive releases at or beyond the facility site boundary. The criteria incorporate the numerous advances in technical capabilities, computer technology, data access, and information sharing. <br>This document begins by describing a common modeling process that explicitly defines requirements and quality assurance ~QA! elements and then examines the need for more complex, variable-trajectory modeling. Ensuing document sections contain criteria for the selection of dispersion model types, relevant timescales, release modes, and removal mechanisms. The remaining sections contain criteria for geospatial data, meteorological data, meteorological networks, and finally QA. Several appendices provide additional information to help the reader choose modeling parameters.