Radionuclide re-entrainment at bubbling water pool surfaces

In case of a nuclear reactor accident involving a failure of the primary system, a liquidcoolant pool, contaminated by suspended or solved radionuclides, may be formed. For scenarios, where gas is injected into the liquid or bubbles are generated, the release of low volatile species from liquid surfaces into a gas atmosphere due to reentrainment/resuspension is identified as a decisive release mechanism. This aerosol source is relatively weak. However, in the late phase of an accident, where radionuclides are possibly accumulated in the pool, this weak but long-lasting source term may contribute considerably to aerosol generation. Depending on the gas flux through a pool, different droplet production mechanisms can be observed. With the modelling of the liquid release from the pool due to film and jet droplet generation as well as the droplet production in case of churn turbulent flow conditions, the resuspension of suspended radionuclides can be quantified as the product of their concentration at the pool surface and the liquid droplet mass flux released.