No it's an engineering problem, these plants were designed without cooling towers because it was assumed the direct cooling using river water would be sufficient in all but the rarest cases.

Presumably it's more of a financial/efficiency problem. Pumping water is expensive, less reliable and a heap of maintenance nightmare compared to passive options. You'd avoid it entirely if it was feasible.

> Presumably it's more of a financial/efficiency problem.

It's absolutely a financial decision, but it wasn't a financial problem. Cooling towers are not free but in the grand scheme of building a nuclear plant they're not expensive either (most power stations — including non-nuclear — have cooling towers).

And "Direct cooling" is not a passive option, you're still pumping water from and to the river or body of water in order to condense steam in the secondary circuit. What you're not doing is semi-closed cycling of that water through a cooling tower, you're feeding the condenser straight from the body of water, and sending water back into it more or less directly (possibly having gone through a radiator of some sort to shed some heat).

Don’t forget the PR aspect, and political cost. A lot of people in France believe nuclear power is carbon intensive because of the plume coming out of the towers.

You can always just evaporate the water, reducing the amount of water to around 0.5 m^3/s per GWe.

That's what's normally done when the body of water is too small, you add a cooling tower, cycle the tertiary coolant through it and compensate for evaporation from the water source.

The issue here is that the body of water is "intermediate", so it was large enough the designer felt they didn't need cooling tower as inflow would be sufficient in all but extreme case, except the extreme case is becoming the normal.