They do. What happens is that either water levels drop sufficiently enough or the temperature of the water in the rivers that they’re drawing from rises to a point that it cannot provide sufficient cooling so they have to turn down or turn off the reactor.
Que? Heat waves don’t trim nuclear output
As this comment (https://feddit.org/comment/14419698) says
In France, Hungary, Romania Nuclear Plants have shut down due to concern over ecological impact or not enough water to cool the plant
Also the jellyfish situation for one of the plants as well.
They do. What happens is that either water levels drop sufficiently enough or the temperature of the water in the rivers that they’re drawing from rises to a point that it cannot provide sufficient cooling so they have to turn down or turn off the reactor.