Cooling can be extremely expensive, in the wrong locations. Diablo Canyon in California uses once-through ocean water for cooling, which is not allowed in new l

Cooling can be extremely expensive, in the wrong locations. Diablo Canyon in California uses once-through ocean water for cooling, which is not allowed in new licenses because of environmental damage. Building cooling towers in the challenging geography there would cost somewhere between $5B-$15B (I can't remember the exact numbers, nor find the source document with all the options evaluated since 2020, the decision was made many years ago). At that cost they decided to shut down the nuclear plant rather than try a cooling retrofit. This is probably an extreme case for costs, however.