Natural Circulation Characteristics at Low Pressure Conditions - PANDA Experiments and ATHLET Simulations

Natural-circulation characteristics at low pressure/low power have been studied by performing experimental investigations and numerical simulations.
The PANDA large scale facility was used to provide valuable, high quality data on natural circulation characteristics as a function of several parameters and for a wide range of operating conditions. The new experimental data allow for testing and improving the capabilities of the thermal-hydraulic computer codes to be used for treating natural-circulation loops in a range with increased attention.
This paper presents a synthesis of a part of the results obtained within the EU-Project NACUSP “Natural circulation and stability performance of Boiling Water Reactors”. It does so by using the experimental results produced in PANDA and by showing some examples of numerical simulations performed with the thermal-hydraulic code ATHLET.