PANDA experiments within the OECD/NEA HYMERES-2 project on containment hydrogen distribution, thermal radiation and suppression pool phenomena

Abstract

In this article, we summarize the experimental results obtained in the large-scale thermal-hydraulics PANDA facility (PSI, Switzerland) within the OECD/NEA HYMERES2 project. The experiments addressing hydrogen distribution allowed characterizing the flow patterns forming from jet flows impacting plates or grating platforms and the following interaction with a postulated hydrogen cloud in the containment dome. The experiments with activation of safety components allowed to compare the effects of multiple spray nozzles with a single spray nozzle or multiple cooler units with unique cooler and to assess the scalability of the related thermal hydraulics phenomena such as pressure histories, power removed, gas mixture distribution. The experiments related to thermal radiation confirmed that the presence of steam in a containment atmosphere even at very low concentration (in the order of 0.1 %) has a significant impact on the evolution of containment mixture temperature.The experiments studying pressure suppression pool phenomena provided insight on the formation and stability of thermocline under a variety of steam release conditions, e.g. from load reduction rings and from multi-hole sparger; moreover allowed to characterize containment pressure histories as function of sparger submergence in the suppression pool.