Predetermination of the thermodynamical state in the DEMONA-facility during aerosol injection with the improved containment code COCMEL

To calculate aerosol depletion in a wet post accident atmosphere, computer codes like NAUA need detailed thermohydraulic data. To meet these requirements the thermohydraulic COCMEL-code, which is a one volume code being widely used for predicting pressure time histories after severe accidents, has been improved by adding new models. This paper describes the models and shows its suitability by some postcalculations of the first DEMONA leakage test (A1). Furthermore, a prediction of the thermodynamical state within the model-containment after injection of aerosols is given. This is important, because aerosols are injected together with a carry gas (air or steam) that has to remove part of the aerosol generators waste heat. Therefore, the injection may change pressure and temperature within the model containment close to design pressure or to values where the instrumentation would no longer work before a sufficient concentration of aerosols might be obtained. It is shown, however, that these problems could be solved by the use of an air-fog resp. steam-fog mixture as a carry gas for the aerosols. (orig.)