Assessment of Nuclear Accident-Related Atmospheric Dispersion Methods and Models to Improve Level 2 PRA models

This study describes the technical, regulatory, design and methodological advancements that affect post-accident atmospheric dispersion modeling since the current EPZ technical basis was established in 1978. Specifically, the study provides the following:

• Reference for NRC acknowledgement of potentially more suitable atmospheric dispersion modeling parameters than those previously provided.

• References for recent advances in near-field effluent characterization.

• Identification and modeling techniques to characterize uncertainty in meteorological conditions.

• Identification of opportunities to address NRC questions regarding modularity through characterization of additional margin in atmospheric dispersion assessments.

• Identification of the potential for greater near-field deposition at SMR sites.

• Description of model fidelity improvement by characterizing dependent nature of various transport phenomena.