[SPOILERS S3] This may be a bit of a silly theory but...

...is the reason that the meltdown in the nuclear power plants that produced the time travel matter, because it happened at the same time that Tannhaus invented time travel in the Origin World?

Granted, we don't know if it happened at the exact same time, but considering the events happened on the exact same date in each of the three worlds, I don't think that it's an unreasonable assumption to make.