Assuming no outside forces suddenly intentionally do something to it. Attacks against infrastructure aren't uncommon. Having infrastructure that is well known to take quite some time to spin down with the consequences being ten thousand years of salted earth is quite a big bullseye.

Which I would still argue is far from making a "when" realistic. This entire comment chain started on the matter of cost. If someone has a reactor, the enemies won't try to explode. They will go Temüjin on it and seize it.