A hydrogen explosion refers to a powerful and dangerous event that occurs when hydrogen gas combines with oxygen and ignites, releasing a significant amount of heat and energy in a sudden burst. Full definition
Three reactors — Units 1, 2, and 3 — sustained severe core damage, and three reactor buildings — Units 1, 3, and 4 — were damaged by hydrogen explosions. (sciencedaily.com)
I'm not claiming that you should connect the negative to the battery terminal, just saying that the risk of hydrogen explosion is lower than what people think. (mechanics.stackexchange.com)
This can have negative safety consequences, including a greater probability of damage from hydrogen explosions. (ucsusa.org)