Method of controlling for the burnable gas concentration

Purpose: To prevent damages in recombiner due to an excess of hydrogen concentration upon loss of coolant accident. Method: The gas temperatures at the inlet and the outlet of the hydrogen-oxygen recombiner are measured, and the flow rate from the reactor container to the recombiner and the recirculation flow rate are controlled so that the temperature difference is smaller than a critical temperature-difference in case where 4 vol.% hydrogen, i.e., the burnable limit gas flows into the recombiner. Thus, since the H2 concentration flowing into the recombiner can always be controlled so as to be less than the burnable limit, the recombiner can be protected from surplus recombination. (Ikeda, J.)