Multiscale Methods for Reactor Safety

Research goals

The overall goal is to improve the simulation of the multidimensional thermal hydraulic phenomena occurring with the core, reactor pressure vessel (RPV) and primary/secondary circuits of nuclear power plants by coupling thermal hydraulic solvers of different spatial resolution and physical models with each other and hence to perform a more realistic description of safety relevant phenomena.  According to this approach, CFD codes can be coupled with subchannel or system codes and a system code can be coupled with a subchannel code. Innovative coupling schemes based on domain decomposition and the ICoCo-method are investigated at KIT.

Potential applications

Multiscale coupled codes paves the way for the use of the different thermal hydraulic solvers in regions of a nuclear power plant where their physical models and spatial resolution assure the best results. For example, in a PWR, the downcomer and lower plenum spatial domain can described by CFD while the core and the rest of the plant by a system thermal hydraulic code. Another example is the simulation of the RPV with a system thermal hydraulic code and the core by a subchannel code.


For the validation of multiscale coupled codes, integral tests of plant data are needed.

Potential applications

Multiscale methodologies can be applied for the improved analysis of thermos phenomena in the core and RPV of different reactor designs e.g.  PWR, BWR, VVER, AP1000, SMRs.

Coupling methodologies