Wow. OK, And you're modded "insightful"
Toshiba (Westinghouse) has decades of experience in the nuclear industry. Their Westinghouse division is one of the oldest players. I'm certain they understand the costs quite well. What you're seeing here is something else (accounting or engineering controls issues at the company they purchased, perhaps)
Reactors only go down for months at a time when something major needs to be replaced. Steam generators. Turbines. entire cooling towers. Same is true of any coal, petroleum, gas, or biomass fired steam boiler. So, to be clear, if you have to overhaul the turbine(s) on your gas fired plant, it's going to be down for a couple of months. Refueling a reactor takes a couple of weeks, a significant chunk of which is waiting for the core to cool off due to decay heat, and bringing the core safely back up to operating temperature afterwards.
Uh, uninhabitable for thousands of years? I think you're exaggerating a bit.