Evaluation of the Split-H Approach to Modeling Non-Buoyant Releases from Vent Stacks.

摘要

Position C.2.b of Regulatory Guide 1.111 describes an approach to modeling the diffusion of effluents from roof top vents and short stacks using an elevated plume model under some conditions and using a ground-level source building wake model under other conditions. The approach is sometimes called a Split-H model. This report: presents the results of an evaluation of the technical basis for and utility of the concept behind the Split-H model, outlines the development of an upgraded Split-H model using existing plume rise and building wake models, compares ground-level, annual average concentrations estimated using the upgraded model with those estimated using the Regulatory Guide Split-H model and a ground-level building wake model, and discusses alternatives to the Regulatory Guide position that the NRC may wish to consider. Concentration comparisons are made using model results for meteorological data from 18 nuclear power plant sites.