To substantially limit the release of fission products beyond the containment; a permanent under pressure is maintained in the inter-containment gap of the V-392 design. This safety function, one of the most important, is fulfilled by two systems: (1) an exhaust ventilation system equipped with a filtering plant with suction from the inter-containment gap and outlet into the stack; (2) a passive system of suction from the inter-containment gap. The first system is intended to control removal of a steam-gas mixture from the inter-containment gap under accidents with the total loss of power. The system is capable to remove at least 240 kg per hour that is equivalent to the inner containment leaks of 1.5% containment volume per 24 hours. The second system consists of the lines connecting the inter-containment gap with PHRS exhaust ducts, which are always in the hot state. This enables permanent removal and purification of inner containment leaks regardless of power supply and operator actions. According to estimations, the under pressure is maintained at any point of the inter­containment gap with inner containment leaks up to 2.8% of containment volume per day (the design basis for the containment is 0.3%). The technical solution described above in combination with the systems for the containment pressure decrease (traditional spray system and new passive heat removal system) allows us to give up the filtered venting system designed for V-392. Even though this system satisfies the current requirements to filtered venting; this should not increase the risk of containment failure. Filtered venting is not required within the short term of a core melt accident.