Dilution factor and atmospheric dispersion pattern for Kalpakkam site

Abstract

Assessment of radiological impact and for planning and preparedness programs, monthly atmospheric dispersion patterns at Kalpakkam have been studied using observed surface meteorological data during 2015–2020. The influence of meteorological factors such as wind speed, wind directions, percent of calm, atmospheric stability, and rainfall on dispersion patterns has been evaluated. The higher wind speed range (>4 m/s) is observed from 11:00 h to 19:00 h with an average wind speed of 4.17 m/s and the highest value observed in the month of May. Extremely stable F category and percent of calm observed to be lowest in the month of June. This study reveals that the high concentration area is toward seaside sectors during the southwest monsoon season from June to September and the remaining months, January to May and October to December, the most probable dispersion toward southwest, South, and North covering land sectors. Wet deposition due to maximum rainfall and more rainy days in the month of November during the northeast monsoon. The study provides site-specific information on dispersion patterns, an essential tool and crucial support for risk management with respect to radiological impact, monitoring and assessment in normal and emergency scenarios of a nuclear facility, and guiding resources for siting and design of the new facility in and around Kalpakkam.