The nuke plant in Ocean County, New Jersey typically shuts down for maintenance in late fall. Thousands of warm water fish which failed to migrate south with the falling water temperatures die.
What is keeping them from simply rescheduling the shutdown to a point where the water has cooled just enough to trigger the migration, instead of waiting until it is cold enough to kill them?
There may be a valid reason, but I’ve never heard it.
Likely some water immersed parts that it would be too cold to service if they waited longer or have seen ice buildup on occasion in Nov. If anything is found in Sep/Oct time frame then they are limited by time to obtain necessary repair parts and complete service. Need to ensure you have time for unexpected discoveries when conducting maintenance.
This would fall during the time when summer peak Air Conditioning loads are over and before the peak heating demands begin.
Spring and Fall are a common times of maintenance for utilities around the nation.