Building more plants is a part of the solution to global warming, but we're nowhere near the warming peak and we are already seeing a crucial part of the solution - the cooling - failing.
Is this something that can be mitigated by building more cooling towers?
Extreme heat and a severe drought do two bad things:
1. Lowers the river level. This threatens to expose the intake pipes drawing in cool water. Those pipes must remain submerged for their pumps to work. They don't rest on the riverbed because they don't want to draw silt from the bottom of the river.
2. Raises the temperature of the water. Lower water levels mean the river has less thermal mass and so the hotter air is warming up the water that much more. That means the cooling water is hotter. This typically isn't a problem as far as cooling the plant itself is concerned but consider that To - Ti (temperature of output - temperature of intake) is constant, so if Ti increases then To must also increase, which as already noted impacts aquatic life. The water may simply be too warm.
Either (1) or (2) is problematic - the two together are a big problem and threaten to shut down the plant. This doesn't just apply to nuclear power units either - coal units, IGCC units and HSRG units face the same issue as do nuclear units. You're right though, this is a big problem getting very little attention. This is one of many reasons why utilities are investing so much into solar and wind - no cooling required.
Cooling towers don't recirculate the drawn water back to the river as far as I'm aware. They only draw the water in the basin depletes. Looking at the sources, 2% of it is lost to evaporation, the rest condenses back on the bottom.
So it doesn't actually draw that much water, and it doesn't dump the warm water downstream.
I have no idea how that stacks up to other nuclear plants, but 100,000,000 m³/y sure sounds like it needs a lot of water.
I wonder if they're considering refrigeration, or if that's even feasible. Conceivably, you could use the power from the nuclear plant to cool itself, since refrigeration has a higher-than-1 coefficient of performance.
You could recondense the steam by dumping the heat into the atmosphere, but that's bigger and more expensive.
You could also store it in thermochemical batteries and save it for winter. The logistics of moving 1t of NaOH every few seconds sound difficult.
You might be able to export it via steam pipe and charge thermochemical batteries on site. That requires logistics that don't exist.
Because apparently letting a river get above 28 degrees for a few kilometers is worth pumping more carbon dioxide into the air.