Calculation of the operation mode of the emergency condenser (EC) of the INKA test facility with ATHLET

The KERENA(TM) boiling water reactor (BWR) is a proven further developed design, based on Gundremmingen NPP and the whole accumulated German BWR operating experience. Especially for the passive safety systems, which are described in the paper more in detail, not only an experimental testing and validation is needed, but also thermal-hydraulic system codes have to be qualified, to be able to consider the mostly gravity driven 3D-flow phenomena correctly. Since in some countries the code ATHLET is well established, it is useful to prove its capabilities or to enhance the capabilities, if necessary. Therefore the FZD in co-operation with E.ON and AREVA is performing a model development and calculations for code validation with help of test results from INKA test facility (INtegral test facility in KArlstein, Germany). The paper gives an introduction into condensation phenomena and describes the condensation models applicable for a special heat removal system driven by natural circulation, it presents a detailed description of the ATHLET-model for the emergency condenser and first results from an estimation of the heat removal power.