PANDA vessel assembly (construction phase, 1993), PSI.

The PANDA project was launched in July 2021, following the NEA HYMERES project series, to contribute to the extension of the database on large-scale containment thermal-hydraulic phenomena. The data are used to enhance lumped parameters or CFD containment thermal-hydraulic codes. Experiments are conducted in the PANDA facility at the Paul Scherrer Institute (PSI), Switzerland. The thematic areas studied include jets or plumes impacting complex compartments, radiative heat transfer, activation of PWR containment spray systems, issues related to pressure suppression pools of BWRs and in-containment refuelling water storage tanks (IRWST) of PWRs, as well as tests related to SMR systems such as passive containment cooling systems (PCCS) and natural convection heat transfer (HT) from the external wall of the containment to the water pool. PANDA is a four-year project supported by 13 organisations from 10 countries. Significant facility upgrades to execute the tests programme, including the data acquisition system, were completed in 2023. The PANDA project is a follow-up of HYMERES 2 and continues to be a pilot project of the NEA Nuclear Education, Skills and Technology (NEST) programme.

In 2024, tests on jets or plumes interacting with a steam generator compartment model, tests to investigate the radiative heat transfer under complex conditions and tests to investigate several complex scenarios with and without containment pressurisation and depressurisation and involving various containment compartments were completed. Tests addressing natural convection heat transfer and SMR-related investigations are planned to be completed by mid-2025.

Discussions are at an advanced stage for a new project phase proposal, PANDA-2 (2025-2029), to extend the database on containment basic phenomena at large scale, on the activation of safety systems, on pressure suppression pools in BWRs, and on SMRs and SMR-related scenarios and systems.