Nuclear reactor freezes game is overheating with 4 quad uranium cells

[inuyasha555]

I was messing around seeing how big a crater the reactor would make, 1-3 cells worked fine and it exploded as expected. The moment I put in 4 and it overheated, it showed the explosion FX but that was it. All mobs froze, destroyed blocks won't yield drops, attempting to close the game from the ESC menu failed to work.

I don't get if this is a bug or what...

EDITL Just happened with only 3 even though it's worked before.