The code system AC2 for the simulation of advanced reactors within the frame of the German EASY project

The reliable simulation of all relevant phenomena occurring during accidents in nuclear power plants (NPP) is an ongoing challenge for the development of computer codes. New generation reactor designs are using more and more passive type systems within their safety systems to cope with accidents. System codes such as the code system AC2 consisting of the modules ATHLET, ATHLET/CD and COCOSYS used in licensing procedures and for safety analyses have to be further developed and validated to be able to simulate such passive systems behaviour.
One aim of the German project EASY is the enhancement and validation of AC2 towards its use for reliable analysis of the behaviour of passive safety systems in nuclear power plants (NPP).
In this paper the work related on the extended coupling between the modules ATHLET and COCOSYS and first results showing the extended capability of the new design of coupling will be presented.
For that the coupling of both codes had to be extended to allow the simulation of the interaction between passive components linked to the primary system with interaction to the containment behaviour. The new coupling concept, using a full interlinked data network and an advanced data transfer between both modules, has in addition an user interface to implement additional modules into ATHLET code. Here new technologies are used to couple both codes improving the modular structure and maintainability.