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Development and Validation of Simulation Codes

One of the key issues of research and development at GRS is to provide reliable methods and procedures for the safety-related assessment of light water reactors. The work comprises the development and validation of computer codes for the analytical simulation of incidents and accidents concerning the reactor core, the reactor coolant system and the containment as well as for probabilistic safety analyses that are carried out for the integral determination of the risk of nuclear power plants. The monitoring and evaluation of national and international reactor safety experiments is an essential part of these activities, thereby forming part of the international reactor safety research network. The results obtained in this context provide the scientific basis for the further development and application of analytical simulation models. Our codes, developed and used at GRS:

•    ASTEC (developed in co-operation with IRSN): integral code for determination of the source term during core meltdown for the primary circuit and containment of LWRs
•    ATHLET: thermohydraulic safety analyses for the primary circuit of  LWRs
•    ATHLET-CD: analyses of accidents with core meltdown and fission product release for LWRs
•    ATLAS: analysis simulator for interactive handling and visualisation of several computer codes
•    COCOSYS: analyses of severe incidents in the containment of LWRs
•    DORT/TORT: solution of time-dependant neutron transport equations for 2D/3D transients analyses
•    QUABOX/CUBBOX: 3-D neutron kinetics core model
•    SUSA: uncertainty and sensitivity analyses
•    TESPA-ROD: core rod code for design basis accidents

The figure below illustrates the interaction of different code systems.

Overview Simulation Codes for Accidents (Source: GRS)