Reactor container

The present invention concerns a hydrogen explosion proof device in a reactor container. Change of hydrogen concentration with time is measured by a hydrogen densitometer and a time variation coefficient calculator disposed in the reactor container. When the amount of hydrogen generated is within a range of usual operation, local increase of the hydrogen concentration is prevented by actuating a blower thereby diffusing hydrogen into the reactor container. Further, if a great amount of hydrogen is expected to be generated, hydrogen is ignited by using an ignitor in a state where concentration of hydrogen in the ceiling of the container is still low, thereby burning hydrogen before the hydrogen concentration reaches a detonation limit. Accordingly, hydrogen in the container can be removed before it reaches the detonation limit thereby eliminating the danger of hydrogen explosion. (I.N.)