In a&nbsp;severe accident of light water reactors, the loss of coolant and heat sink can cause core degradation. The molten fuel pellet (UO2), molten cladding material (Zr-ZrO2), and molten structural&nbsp;materials&nbsp;(stainless steel) form molten corium, and finally relocate in the lower head of the reactor pressure vessel (RPV). In case of coolant&nbsp;loss, the corium molten pool form in the lower plenum which will threaten the integrity of RPV. To prevent the RPV failure, the ex-reactor vessel cooling (ERVC) system, which floods the RPV with cooling water, is applied to ensure the survivability of RPV eventually achieve the goal of fission product retention.&nbsp;Therefore, the molten pool’s behavior is well studied by a large number&nbsp;of experiments, such as&nbsp;BALI, LIVE-2D, COPRA. Natural heat convection, which is related&nbsp;to the latent heat of fission products&nbsp;and the cooling&nbsp;of ex-vessel, will induce heat flux alone the RPV lower plenum. The peak value of heat flux&nbsp;is&nbsp;estimated at around 70°. However,&nbsp;there is still uncertainty to predict the Nuup/Nudn&nbsp;ratio especially when the result of the prototype molten pool (1017) to be extrapolated. This research&nbsp;aims at&nbsp;analyzing the scale effects based on Puckinhum’s PI theory. The molten pool phenomenon&nbsp;related to dimensionless parameters&nbsp;is firstly calculated. After rigorous calculation, the influence of each dimensionless parameter&nbsp;is&nbsp;evaluated according to the behavior of the corium pool. Finally, the experimental results&nbsp;of BALI and COPRA are obtained, in order to evaluate the uncertainty between the chosen simulant&nbsp;from those two experiments.

Research on Dimensionless Analysis Method of Scale Effects for Molten Pool Experiments

Paper Proceedings: https://asmedigitalcollection.asme.org/ICONE/ICONE28/volume/85246

2021 28th International Conference on Nuclear Engineering (ICONE28)

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