Swedish nuclear reactors are all located at the North Sea or Baltic sea that's cold enough all year round, we don't have that issue.

This is mostly an issue for ("partially") landlocked countries. Those french reactors use rivers for cooling. Also the summer period neatly coincides with the yearly maintenance period, so...

This was to prevent the water in the rivers from heating up past the point where it's safe for wildlife. Nuclear plants that use ocean water for cooling don't have this problem.