Estimation of air-to-grass mass interception factors for iodine

Abstract

Air-to-grass mass interception factors for radionuclide are important basic input parameter for the estimation of radiation dose to the public around a nuclear power plant. In this paper, we present the determination of air-to- grass mass interception factors for iodine using a 2 m × 2 m × 2 m (l × b × h) size environmental chamber. The temperature, humidity, and rainfall inside the environmental chamber was controlled to required values to simulate different environmental conditions. Grass (Pennisetum purpureum, Schum), grown in pots, was kept inside the environmental chamber and stable iodine in elemental form was sublimed quickly inside the chamber to simulate an accidental release of iodine to the environment. The concentration of iodine in the air was measured periodically by drawing air through a bubbling setup, containing 1% sodium carbonate solution. The mass interception factor for dry deposition varied in the range of 0.25-7.7 m² kg^-1 with mean value of 2.2 m² kg^-1 with respect to fresh weight of grass, and that due to wet deposition varied in the range of 0.6-4.8 m² kg^-1 with mean value of 2.3 m² kg^-1. The mass interception factor was inversely correlated with the total iodine deposited through dry deposition as well as with the rainfall.

Keywords: Deposition rate; Deposition velocity; Emergency situation; Iodine; Mass interception factor.