Overview on the development and application of the coupled code system ATHLET-QUABOX/CUBBOX

An overview is given on the development and the application of coupled codes in GRS on the basis of coupling the fluid-dynamic system code ATHLET and the 3-dimensional reactor core model QUABOX/CUBBOX. The features of coupling both codes are described and different types of coupling are discussed. Results and experiences of the coupled code ATHLET-QUABOX/CUBBOX for the international OECD LWR core transient benchmarks, the PWR Main Steam Line Break (MSLB) Benchmark and the BWR Turbine Trip (TT) Benchmark, are summarized. As best-estimate calculations should be supplemented by an uncertainty and sensitivity analysis, an example of such a study applying the GRS method for coupled codes is presented. In addition, further steps of coupled code development are discussed like implementing a switch between 3D kinetics and point kinetics, integrating direct neutron transport solution methods and coupling of multi-dimensional two-phase flow models. (authors)