•Modeling of RELAP5/SCDAP and CONTAIN containment are prepared for VVER 1000/V446.•Double-ended loss of coolant accident is simulated.•The core degradation map and hydrogen generation are evaluated.•Distribution of H2, O2, N2, and H2O (liquid and steam) are investigated in the containment cells. In this paper, a double-ended loss of coolant accident with station blackout condition is modeled for VVER-1000/V446 using RELAP5/SCDAP mod3.4 as a best estimate nuclear code. Besides, the cells of containment rooms are modeled exactly according to safety reports of this reactor using the CONTAIN 2.0 computer code. The breaks mass flow rates of coolant in liquid and vapor phases, hydrogen generation rate, and oxidation heat generation data are extracted from RELAP5/SCDAP code and used as the input data for CONTAIN code. The hydrogen, vapor and liquid water release to the containment through the break. It can lead to the pressure of containment increases and failure can occur due to overpressure. The containment pressure and temperature in the containment dome are evaluated during the one day. In addition, the local hydrogen generation and mixture gases are investigated in the cells of containment after 24 h.