Simulation of currents and aquatic transport of radionuclides in coastal waters near Kalpakkam coast of India using Delft3D

Abstract Modelling of transport of radionuclides in the coastal waters of nuclear facility sites (during routine releases of active effluents and in case of accidental discharges of radionuclide) is important for radiological safety analysis. In this study, the aquatic currents and associated transport of a contaminant has been modelled (considering a hypothetical release) for Kalpakkam region under different seasonal conditions [South-West (SW) and North-East monsoons (NE)]. The surface wind field which is important for setting up the aquatic currents has been simulated (using WRF model) and subsequently the outputs have been coupled with Delft3D hydro-dynamical model in offline mode. Simulations indicate that both the large scale monsoonal atmospheric flow and the local range land and sea breezes influence the coastal currents at the site. A correlation of 0.48 to 0.65 between the simulated and observed currents approximately at 600 m away from the coast has been noted for SW and NE flow conditions. Simulations indicate that the local currents influence the dispersion of contaminants near the Kalpakkam coast and this effect is predominant during the SW monsoon where frequent alteration in the direction of currents has been observed. Simulations indicate that the dilution factor after 48 h of continuous release at 1 km distance from the release point varies between 2.9E-3 and 5.1E-5 s/m 3 for SW and NE flow conditions.