The VVER-1200 reactor is one of the leading Generation 3+ nuclear power plant technologies currently available on the market. In Europe several VVER-1200 type power plant units are being built or are being designed and licensed. The appropriate safety analysis of these reactors is crucial not only for the successful licensing but also for the safe long term operation of the power units. Important feature of the VVER-1200 technology is that active and passive safety systems are combined to cope with Design Basis Conditions and Design Extension Conditions and to fulfil the requirements set by the Nuclear Safety Codes.

For the analysis of thermal-hydraulics processes within the power units different system codes can be applied. One of the leading, state-of-the-art simulation tools is TRACE (TRAC/RELAP Advanced Computational Engine), which is the flagship thermal-hydraulics analysis program of the US Nuclear Safety Regulatory.

There is no system model available in TRACE for VVER-1200 reactors. The task of the PhD candidate is to develop, verify and validate a system model for VVER-1200 using TRACE, analyze DBC and DEC scenarios with special emphasis on small and large break loss of coolant accidents (SB/LB-LOCAs) and main steam line break events. A further task is to evaluate the operation and effectiveness of active and passive safety systems of the VVER-1200 reactors.

The PhD candidate would perform the following tasks:

• Study the latest development in the international literature on thermal-hydraulics and system analysis of pressurized water cooled reactors.
• Evaluate and compare the available publications on VVER-1000 and VVER-1200 thermal-hydraulics system code analysis.
• Develop the system model of VVER-1200 using the code environment of SNAP and TRACE. (If it is necessary for the analysis reactor kinetics model could be taken from other development.)
• Verify and validate the code environment and the developed system model.
• Select the exact scope of the safety analysis.
• Conduct best estimate calculations for the selected transients.
• Compare and analyze the simulation results. Set the calculations against the relevant regulations of the Nuclear Safety Codes.
• Evaluate the function and effectiveness of active and passive safety systems during the selected transients.
• Make an outlook how the developed system model and its results could be used for education and training purposes.