In the designs of the new-generation reactor facilities, including floating nuclear heat and electricity plants, new passive containment safety systems are used to increase operational safety. The objective of the present work is to validate experimentally the effectiveness of heat removal by a system which lowers damaging pressure levels in the protective shell under conditions of the maximum anticipated accident with loss of coolant in the first loop. The results of the experimental studies on a full-scale model of a secondary loop of the first cooling loop for lowering damaging pressure confirm the validity of the technical decisions made; all prescribed design characteristics of the cooling loop are upheld.