Speaker
Description
Severe accident management (SAM) measures play a significant role in mitigating severe accidents in
nuclear power plants (NPPs). Their proper design requires a thorough understanding of processes
leading to severe accidents and the related phenomena. As SAM measures are being increasingly
considered in regulation of NPPs operation, it is of utmost importance that suitable database is
available for validation of safety analyses codes to facilitate a better understanding of mitigations
systems performance and their impact on progression of an accident.
In support of such activities, THAI research program aims at investigating open questions relevant for
safety assessment of water-cooled reactors, with specific focus on containment safety research under
severe accident conditions. Experiments are conducted in the frame of national project sponsored by
the German Federal Ministry for the Environment, Nature Conservation, Nuclear Safety and
Consumer Protection (BMUV), and international projects which run under the auspices of OECD
Nuclear Energy Agency (NEA). The ongoing THAI national project involves experimental research
related to water-cooled small modular reactor relevant topics, and OECD/NEA THEMIS project has a
specific focus on investigating effect of late phase conditions on hydrogen risk and source term related
issues, among others.
The present paper will discuss a selection of THAI experiments related to active and passive safety
systems performance, impact of late phase conditions (e.g., CO, O2 lean atmosphere), and fission
products remobilization from surfaces and/or water pools. The experimental database facilitating
assessment and validation of safety analyses tools towards mitigation, and management of severe
accidents will be highlighted with selected examples of international code benchmarks conducted
based on THAI data. Finally, planned re-orientation of THAI experimental research in the frame of
future national and OECD/NEA THEMIS follow-up projects will be briefly discussed with emphasis
on passive safety systems related investigations including those relevant for water cooled SMRs.
