[en] The vessel structural integrity is one of the key issues in the analysis of possibility of the in-vessel melt retention. The system pressure and thermal hydraulic behavior of the relocated molten materials determine loads, stresses and displacements of the reactor vessel and finally failure mode and time to rupture. Recently several experiments have been conducted at Sandia National Laboratories on creep rupture of a pressurized reactor lower head scaled model (1:5). In the tests pressure was about 10 MPa and temperature was about 1000 K. Different thermal loads were simulated by resistive heating of the inner surface of the hemisphere. For the analysis of RPV structural integrity finite element codes are usually used for predictions of vessel failure. Data obtained in the SNL LHF experiments can be used for validation of models. The objective of this paper is to simulate LHF-1 and 2 experiments by the developed HEFEST code utilizing finite element approach. Results of FEM analysis of these experiments are supplemented with the studies of uncertainties of code predictions with the simplified approach realized in the LOHEY code. It was found that the main source of uncertainties in the analysis is high temperature material properties data. Results of analysis are compared with the experimental results. Previously the LOHEY code has been benchmarked and used for TMI-2 accident simulation