Nuke refueling outages tend to run on 16 month cycles. If the outage is in the spring, then the next one will be a year (plus) in the fall and back and forth it goes.
I participated in 6 refueling outages. No two were alike in down time, but they always kicked off as planned on the 16 month cycle. The one I worked at- when down, lost a million dollars a day net for the inability to produce and sell energy, AND there was the added cost (loss) in the refueling expenses.
I defer to others who might correct me.
If you worked during the refueling outages, then you know more than I do. At the same time, the one nuke plant in Texas I have toured is on an 18 month cycle. Like you said, the planning is like clockwork, and it never stops. They start planning the next one as soon as the current one is complete.
The problem that caused the reaactor to trip and shut down was reported to be a disruption in feedwater pumps 11 and 12. And that disruption was caused by some equipment that hadn't been hardened for the extreme cold temperatures that occurred this week, despite warnings that such extreme weather was going to hit.
The details are in the Washington Examiner article, "How and why a nuclear reactor shut down in Texas cold snap when energy was needed most," and NRC EN Revision Text: AUTOMATIC REACTOR TRIP DUE TO LOW STEAM GENERATOR LEVEL.