How Climate Change May Affect Nuclear Power Plants

I usually see this argument presented as a nuclear-only problem and a safety risk: "but if the reactors aren't cool enough there'll be a disaster"! I note UCS only says it's "likely" there's a sound safety argument; I can't actually see any problem whatsoever, safety-wise.

I think it's worth mentioning that the reason there are temperature limits for coolant water in *all* thermal-cycle plants, fossil fuels included, is purely environmental. Water discharged above a certain temperature risks harming the local environment, and thus is not permitted; in warm weather the plant has to keep coolant water on site in cooling ponds for longer. Plants, obviously, have limited capacity to do this; so when the ponds are getting too full they need to shut down and stop producing heat - not because it'd be dangerous to do otherwise, but because without the coolant water in the turbine, the electrical output of the plant drops dramatically, and it becomes uneconomical to operate. Basic thermodynamics, the energy that can be extracted from the system is inversely related to the temperature gradient between the hottest and coldest points within it.

Reactors in particular operate at well above the boiling point of water, so you could literally use steam as a coolant if necessary, as long as the coolant pumps are still working (accidents occur only if the coolant pumps fail).

Good article as far as unexpected global warming impacts go; but a little light on some key facts, and sounding rather too much like it's purely a problem for reactors.

Not just nuclear plants, but all thermal plants require cooling, typically by water. These include coal plants, combined cycle natural gas plants, geothermal plants, and thermal solar plants.

Rather than heating rivers, lakes, or oceans, some thermal plants evaporate water in cooling towers in order to generate electricity from turbine/generators. 

Advanced nuclear power plants that operate at higher temperatures have high efficiency and need less cooling than today's plants. Direct air-cooled power plants are also possible at high temperatures generated by thorium molten salt reactors such as LFTR (liquid fluoride thorium reactor). A new book, THORIUM: energy cheaper than coal covers these topics. It is described at http://www.thoriumenergycheaperthancoal.com

"Drought and water shortages, also caused by the change in weather, could potentially become a problem ..."

Let's not forget the critical water dependence of hydro power and biomass/biofuels!  In fact, the problem effects all dispactable power except simple cycle natural gas turbines (which use almost double the fuel of a combined cycle gas plant with the same output).  Without dispatchable power, we simply have no practicle way to use variable renewables: solar PV, wind, & wave (at least for those communities that lack the geography or funding for pumped-hydro storage).

Of the important thing is not what happens at thirty year plants, but rather the choices we make for future plants.  As Robert's comment explains, with nuclear, we can choose dry-cooled plants that need no water.

I find it ironic that environmentalists insinuate that globlal warming is dangerous for nuclear power plants. Envirnmentalists ought to be embracing nuclear power as the best hope for reducing global carbon emmissions,