111 DESCRIPTION OF THE NATIONAL TECHNICAL UNIVERSITY OF ATHENS (NTUA), DISPERSION MODEL The NTUA model is an Eulerian dispersion model based on the solution of the equation: ? ?? (??) + ? ? (?????) = ? ? (????) (VII-1) where C is the radionuclide concentration, ? is water density, v is water velocity and ?s is the kinematic viscosity of seawater. The 137Cs sediment concentration was calculated using the relevant distribution coe?cient kd. The finite–volume method was implemented for the numerical solution of the di?erential equations.