Qualification of RELAP5-3D Code Against the In-pool Passive Energy Removal System PERSEO Data

Improvements of RELAP5/Mod3.3 heat transfer capabilities for simulation of in-pool passive power removal systems

“…Several works are found in literature dealing with the application of different versions of RELAP5 for the simulation of PERSEO experimental tests. Still, similar outcomes were found by different researchers, namely, that the heat transfer model between HX and pool must be refined (Ferri et al, 2005;Narcisi et al, 2020b; Annals of Nuclear Energy 160 (2021) 108436 https://doi.org/10.1016/j.anucene.2021.108436 Bianchi et al, 2004;Bersano et al, 2020). Narcisi et al (2020b) focused the attention on the evaluation of the Heat Transfer Coefficient (HTC) in pool boiling and in condensation within vertical tubes under low flow regime.…”

“…The low accuracy of R5 in simulating film condensation in particular conditions have been mentioned in section 1. Bersano et al (2020) questioned the applicability of Eq. ( 7) to model such passive safety systems, characterized by relatively large tube diameter.…”

“…In this case, steam velocity is too low (around 2 m/s) and Nusselt HTC results higher than Shah formulation. Thus, Nusselt HTC is applied over the whole tube length, resulting in the miscalculate of the heat transfer (Bersano et al, 2020). Is worth noticing that Shah (1981) suggested to use Eq.…”

“…The enhancing factors assume the following values: 9 for pool boiling mechanism and 1.3 for condensation (applied to the Vierow and Schrock (1991) modification of the Nusselt model). Bersano et al (2020) interrelated the considerable underrate of the heat exchange to the condensation HTC. They analysed different sets of correlation to improve the HTC esteem, deriving an enhancing HTC factor of 3.54, applied to the Nusselt model.…”

Passive safety systems analysis: A novel approach for inverse uncertainty quantification based on Stacked Sparse Autoencoders and Kriging metamodeling

“…We show the application of the IUQ methodology to a TH RELAP5-3D model [51] developed by Politecnico di Torino [52] for the PERSEO test facility (sketched in Figure 4) [53]. For more details about the facility, please refer to [53,54].…”