Q-9
What was the source of the hydrogen that caused an explosion at Unit 4 ?
A：
Because Unit 3 and Unit 4 shared the same exhaust stack, it is suspected that, during the venting of Unit 3's containment vessel, hydrogen from Unit 3 traveled through the exhaust line to Unit 4 and entered into Unit 4's reactor building.This has been substantiated by the fact that Unit 4's heating, ventilation and air conditioning system was contaminated more severely on the downstream side.