Re: [Phys-l] Eartquaque in Japan

[Hugh Haskell <haskellh@verizon.net>]

At 23:42 -0700 03/19/2011, Bernard Cleyet wrote:
> I thought it was a much smaller amount recycled, 
> as is in an automobile's radiator.
The water drawn into the cooling tower from a 
reservoir is sprayed over the pipes to condense 
the steam from the low-pressure side of the 
turbine, is mostly evaporated. So the water usage 
of 20 million gallons a day is evaporated water. 
Of course much of it comes down further downwind 
as rain--some of which falls into the ocean and 
is, for all practical purposes, lost--but it is 
certainly no longer available at the location 
where it was used to cool the steam. So the 
reservoir of cooling water must be replenished 
daily by that amount--20 million or so gallons 
for each reactor it serves.

Reactors that use a once-through cooling system 
pass about 100 million gallons a day through 
their condensers. The don't use cooling towers 
and there is little evaporation, but the water 
discharged is much hotter than when it entered 
the condenser--by 20-30 °C. This can have 
detrimental effects to the downstream ecology of 
the river, or sea that the water is discharged to.

So you pay your money and you take your 
choice--use a cooling water reservoir and the 
cooling towers and lose 20 million gallons a day 
to the atmosphere, or use a once-through system 
and dump 100 million gallons a day of hot water 
into the downstream waterway.

I think there have been some air-cooled reactors 
proposed and perhaps a pilot plant or two built, 
but air cooled reactors are not used in any 
commercial power generating systems today.

Hugh
--

Hugh Haskell
mailto:hugh@ieer.org
mailto:haskellh@verizon.net

It isn't easy being green.

		--Kermit Lagrenouille