The simulation of melt spreading with THEMA code: Part 2: Assessment against spreading experiments

In the frame work of R&D on severe accidents for PWRs, definition of mitigation means for cooling of the molten core after a vessel melt-through is of utmost importance. In the case of spreading-based concepts, the THEMA code, which considers integrated balance equations over the fluid depth, aims at predicting the spreading extent of non eutectic mixtures under defined inlet conditions (pouring rate, temperature and composition). In a first part, the models and the assessment strategy of the code have been presented and the correct running of the main moduli of the code have been assessed by comparing the numerical results against known solutions of basic problems. In this second part, the results of the validation of the code against experiments conducted with low or high temperature simulating materials as well as prototypic melts are presented. It is concluded that the code has reached a sufficient level of confidence to make predictive reactor applications.