Validation of ice condenser model for CFD analysis of VVER-440 type containment

The Loviisa nuclear power plant is a unique combination of nuclear technologies, consisting of a VVER-440 reactor and an ice condenser containment. The Loviisa ice condenser is divided into two separate sections contrary to the original design applied in the USA and Japan where the ice condensers consist of a single section. The VICTORIA experimental facility is a 1/15th scale model of the Loviisa containment, which was constructed by Fortum to provide essential experimental information on the thermal-hydraulic behavior of the Loviisa ice condenser containment during small break loss-of-coolant accidents (SBLOCA) and severe accidents. Computational fluid dynamics (CFD) analyses can give detailed information on the flow, temperature and pressure behavior in the ice condenser containment of Loviisa. NRG has validated CFD models for analyzing the thermal-hydraulics in containments of NPPs, making use of the CFD code ANSYS Fluent. In a joint research project, Fortum and NRG developed an ice condenser model that was integrated in the CFD containment model of NRG. This extended CFD containment model, including the ice condenser model, is validated against two experiments from the VICTORIA facility: experiment 27, in which the facility is pressurized and heated by injection of steam without ice in the ice condensers, and experiment 44, in which steam and helium is injected into the facility with 50% ice loading in the ice condensers. It is shown that the evolution of pressure, temperature and helium concentrations in the VICTORIA facility can be predicted qualitatively well by the CFD model. Although this is a valuable first step, further development and validation is necessary before the CFD ice condenser model can be applied on real scale for safety analyses of the Loviisa NPP.