SWIFT-RIMPUFF Modeling of Air Dispersion at a Nuclear Powerplant Site With Heterogeneous Upwind Topography

The SWIFT-RIMPUFF can provide refined atmospheric dispersion modeling for nuclear emergency response, but its performance for the mesoscale range in a nuclear power plant (NPP) site with highly complex topographies hasn’t been fully investigated. In this study, a validation of SWIFT-RIMPUFF was performed based on a wind tunnel experiment simulating a real China’s multi-reactor NPP site with heterogeneous upwind topography and dense buildings to understand the potential discrepancies or limits. The results demonstrate that the SWIFT-RIMPUFF can reproduce the sharp changes of wind flows for both speed and directions near the buildings, but usually overestimate the wind speed in the complex topography. For vertical wind profiles, the accuracies show high dependencies on the local topography and building layout, and the deviation of those near the building is more obvious. The simulated ground concentrations match the topographic changes of high-altitude mountains. The concentration predictions in the downwind building area are acceptable which displays that the influence of building effects can be well introduced, but the simulations in the building area still show noticeable discrepancies when compared with those in the sea area. However, such deviations do not propagate to the downwind mountainous and sea areas, which the accuracies are quite satisfactory.