Method of controlling the operation of a waste gas recombiner

Purpose: To enable to render the hydrogen concentration in a discharge gas condensator sufficiently lower than its burnable boundary when the thermal power of the nuclear reactor is lower than the rated thermal power. Constitution: The nuclear reactor has a monitor capable of measuring the thermal power for a wide range, and the opening degree of a flow control valve disposed to an air injection pipe is adjusted when the thermal power measured by the monitor is within the range from 0.01 to 5 % of the rated thermal power, and the air is injected to the downstream of a discharge gas recombiner. Further, when the hydrogen concentration in the discharge gas flowing into the recombiner is within a range from 4 x 10-4 to 0.2 volume %, the air is injected to the upstream of the recombiner. Then, it is confirmed by the hydrogen densitometer whether the hydrogen concentration at the downstream of the discharge gas condensator is sufficiently lower than the burnable boundary. (Yoshino, Y.)