The good news is that after it is paid for, it will cost about $20-$25/MWh. The bad news is that at least for the few decades it will cost $75, which is about the same as solar+battery LCOE today.
Those numbers are wildly optimistic, these overruns mean the plant is going to be repaying construction costs over it’s full lifespan.
I don’t know where you messed up but if you’re running the numbers include the full cost not just the overrun, interest rates, increasing operating costs during loan repayment, capacity factor, and decommissioning costs. Opening costs late in life is a real killer as older power plants mean ever more equipment needs to be replaced which then lowers capacity factors etc.
