Experience in qualitatively appraising the effect that the quality of the coolant has on the reliability of items of the equipment at nuclear power stations with RBMK-1000 reactors is presented. A correlation between the quality indices of the coolant and the reliability of the most important items of equipment in the multiple forced circulation circuit (MFCC), including the fuel-rod assemblies, is established. The quality of the coolant depends on the operating reliability of the condenser installation, the sensitivity and adequacy of the pickups of automated chemical control (ACC), and the efficiency of condensate polishing. Using correction technologies improves the operating reliability of the items of the equipment.