FIELD: nuclear reactors using liquid coolant. SUBSTANCE: cooling circuit preferably has pressurizer tank 6 and at least one high-pressure pump 60, 62. Hydrogen makeup point 38 is provided in admission pipeline 32 on suction end of high-pressure pump 60, 62. Delivery side of high- pressure pump 60, 62 incorporates metering line 82 communicating with pressurizer tank 6 or with drain system 94. Coolant hydrogen content metering device is inserted in this line and connected to control device 52. Control valve 42 is provided in hydrogen feed pipeline 36. EFFECT: enhanced speed and precision of controlling coolant hydrogen content. 9 cl, 1 dwg
