2019:03 Evaluation of the hydrodynamic model in PARET/ANL


The fuel rod analysis program SCANAIR has been developed by IRSN (Institut de Radioprotection et de Sûreté Nucléaire) for analysis of reactivity initiated accidents (RIA) in light water reactors. The Swedish Radiation Safety Authority (SSM) has access to SCANAIR in exchange for annual contributions for its further development. This ensures a possibility for SSM to do own analysis of fuel rods in reactivity initiated accidents. The development and administration of the program is done by Quantum Technologies AB on assignment from SSM.

SSM’s development of SCANAIR is primarily focused on the thermohydraulic models, with the aim of improving the analytical capabilities for fuel in boiling water reactors. In a previous work, a two-phase flow model was developed, which was incorporated by IRSN in SCANAIR V_7_5. The present work is the 2017 contribution to SCANAIR development and contains an evaluation of alternative models and concepts that will improve the aforementioned two-phase thermohydraulic model in SCANAIR. The model is based on the two-phase hydrodynamic model used in the PARET/ANL computer program developed by Idaho National Laboratory (INL) and Argonne National Laboratory (ANL) in the 1960s.


This current project has identified and assessed hydrodynamic models that would facilitate a better description of the effects of water density, the difference in velocity between water and steam and the friction in the water channel, if implemented in SCANAIR. Improvements like these lead to a better understanding of the phenomena that are acting during an event and will in the future result in better analytical models for the safety analysis of nuclear power plants.


Knowledge of phenomena occurring in a fuel rod during an event and how these phenomena are implemented in analytical tools is essential to SSM for the supervision of nuclear power plants. The current project also enables SSM to actively be a part of the large efforts that are made internationally with testing, understanding and improving the tools for analysis of reactivity initiated accidents.