In this article the results of experiments on boiling off a coolant in the assembly of rods ADELA-2 and ALADIN test facility were considered. During the work, the ADELA-2 and ALADIN test facilities were simulated using the KORSAR and SOCRAT thermal hydraulic codes. The effect of the degree of spatial discretization on the calculation results was estimated and it showed that the results of the calculated data are in acceptably good accordance with the experimental data. Between the calculated and the experimental time of uncovering the rods and reaching the maximum temperature only small deviations appear. Moreover, the results obtained with the codes in most cases give an underestimation of the moment of exposure in comparison with experiments.