Pete,
like you, I'm more familiar with once-through cooling systems.

Actually, evaporative cooling systems, excluding latest 'keller'? models which
only consume 5% of the water they draw off, use about 20 to 30% of the water
they draw off. The salt washout is usually a very low flow leak off, a few
hundred gallons an hour...and back into the source water.

Once through has almost NO evaporation loss at all. The reason for this is that
in most places, regulations keep the outfall water as it passes through the
condensers within 10 to 25% of the input water temperature. At my plant, which
uses ocean water from a bay, the input water temp is approx 60 F in
summer...outfall water never exceeds 10 to 15 F more than that, often it's as
low as 7 F difference (winter time). This water mixes immediately with the bay
water and so evaporation is hardly more than what is natural given ambient air
temperature and humidity.

EDF is beginning to address this issue with more advanced cooling tower designs
and, multi form cooling such as a combination of river/air cooling and so on.
The best solution, of course, is to build coast side, with the vast and VERY
cold north Atlantic heat sink. Then it's totally a non-issue except for the very
localized area where temperatures could get raised, a bit.

D
David


--- In Know_Nukes@yahoogroups.com, "schedule80" <schedule80@...> wrote:
>
> This gets more questionable the more I look into it. There are descriptions,
usually with pictures, of the French nuclear stations in Wikipedia. Almost all
of them have cooling towers. Therefore, the vast majority of their waste heat is
going up the towers, not into the rivers. Sure, with an evaporative cooling
tower, they have to draw off a small amount of water to keep the salts from
building up, and that water is returned to the river, but how much could these
plants increase the downstream temperature?
>
> I'm more familiar with once-through cooling. Isn't the draw-off water from a
cooling tower taken out after the heat has been removed? And what percentage of
the circulating water flow is drawn-off? Maybe 10%? I can understand how a
once-through plant would have an effect on the river, but with cooling towers,
there just isn't that much heat going back.
>
> Anyone here have experience with cooling towers and the associated temperature
increases in a river?
>
> The French Cruas plant has very nice artwork on one of its towers.
> http://en.wikipedia.org/wiki/Cruas_Nuclear_Power_Plant
>
> More cooling towers. The French prefer to standardize their designs, no?
> http://en.wikipedia.org/wiki/Dampierre_Nuclear_Power_Plant
> http://en.wikipedia.org/wiki/Cattenom_Nuclear_Power_Plant
>
> It appears two of the plants at Bugey use once-through cooling, while two use
towers.
> http://en.wikipedia.org/wiki/Bugey_Nuclear_Power_Plant
>
> From what I can tell, cooling towers for their inland plants are the norm,
with just a few exceptions.
>
> - Pete
>
> --- In Know_Nukes@yahoogroups.com, "David Walters" <dave.walters@> wrote:
> >
> > Wow...considering fresh water IS radioactive, that would be a hard hurtle to
pass.
> >
> > Kind of like the panic over the Japanese earth quake in 2007 where there was
a "radioactive spill" of several hundred gallons. Only problem was that the
radioactive level of the spilled water was *less* than the notably radioactive
water in the Sea of Japan.
> >
> > Bureaucrats...
> >
> > david
> >
> > --- In Know_Nukes@yahoogroups.com, esbuck@ wrote:
> > >
> > > Yes, it is difficult to cool a reactor with intake water that is warmer
> > > than the discharge water. NASA had a small research reactor at their Plum
> > > Brook facility, but they were faced with regulations which demanded that
the
> > > output water be less radioactive than the input water. Needless to say,
> > > that reactor did not function and was a waste of money. Oh, well, that's
why
> > > we have taxes.
>