Modeling liquid-gas iodine mass transfer under evaporative conditions during severe accidents

Abstract

During postulated severe accidents transfer of volatile iodine dissolved in containment water sumps to

atmosphere can be fosteredunder pool evaporative conditions. Scarcity of representative data has resulted

in semi-empirical models that relies on fitting parameters and still need of further validation. This paper

presents a mechanistic model based on: the two-film model, the heat-mass transfer analogy and the

surface renewal theory. Comparison to data fromthe SISYPHE program, performed at the French “Institut

de Radioprotection et de Sûreté Nucléaire”, has resulted in an accurate response, the error band being

9–25% for the aqueous steady state concentration. Likewise, the model performance has been compared

to the model implemented in the ASTEC code. In addition to yield similar results, some advantages have

been highlighted: the mechanistic nature, the estimates conservatism, and the thorough documentation

of model grounds and assumptions.