Refueling and maintenance are the "normal" things and both are planned to the time of year with least consumption/lowest electricity prices.
Then you have the rare non planned outages but once a new reactor has been running for a year or two and all the kinks have been worked out they should be very rare.
Then you have the rare non planned outages but once a new reactor has been running for a year or two and all the kinks have been worked out they should be very rare.