TVA reactor shut down; cooling water from river too hot

[phantom power]

A new way for climate change to suck:

The Tennessee Valley Authority shut down one of three units at the Browns Ferry nuclear plant Thursday because water drawn from a river to cool the reactor was too hot, a spokesman said.

The nation's largest public utility shut down Unit 2 about 5:42 p.m. CDT because water drawn from the Tennessee River was exceeding a 90-degree average over 24 hours, amid a blistering heat wave across the Southeast.

"We don't believe we've ever shut down a nuclear unit because of river temperature," said John Moulton, spokesman for the Knoxville, Tenn.-based utility.

http://www.chron.com/disp/story.mpl/business/energy/5061439.html

[snappyturtle]

1. I can't tolerate much more good news!

:sarcasm: Just in case anyone is wondering..........

[Donnachaidh]

2. We haven't had cold water all week

I'm nervous about using my tapwater filter because the cold tap ISN'T cold. We've had 100+ temps all week.

[phantom power]

3. you folk in the southeast have really been taking a beating.

I saw 107F in Tennessee last night -- WTF?

[Donnachaidh]

9. yup, and not much relief in sight

We had 110 heat index two days ago. A crazy electrical storm in the middle of the night only cooled things temporarily. But the faucet water being what I consider HOT (well, not burning hot but certainly NOT cold, even after running it) totally blew my mind. Critters had to have ice in their waterbowls.

[donsu]

4. and nuke water being too hot is going to happen more and more

the Gulf of Mex. water is so hot I'm surprised the Fl. nuke plant is still on. it must be near the limit.

unless the plants are stealing the cold water from the famous Springs?

[thunder rising]

6. and Hurricane Dean is out there

just about to hit the hot spot. FYI Wilma was the most intense storm recorded until just before landfall. But even as a Cat 2 it had enough power to cut a swath all the way across FL.

The tracks have to slightly moving northward perhaps missing the Yucatan peninsula. If it goes unobstructed into the gulf it will be interesting to watch this puppy.

Is the Preznit still on vacation? Katrina Part II is about to unfold and he could have a chance to show he actually gives a shit about the USA about now.

[phantom power]

5. This also raises the question about impacts on other industries...

nuclear reactors aren't the only industrial devices that use water for cooling.

[donsu]

7. interesting - is there a list of ind. that must use cold water?

nt

[phantom power]

8. I don't think the issue is "must" so much as "designed assuming"

I don't actually know of any specific examples, but people have been using water as a heat-exchange medium since the discovery of coal, if not before. I find it hard to believe that somebody out there isn't using river water, and that the original engineers simply assumed a historical temperature range when they designed the cooling systems.

I suppose I might be wrong. Maybe nuclear reactors are truly the only devices that do this, but it would defy my intuition.

[kestrel91316]

10. Summers here in the Valley, it's always so hot that you don't need

to run the HW tap. Just turn on the CW tap and it's warm enough for most purposes............sigh.

Tennessee River 90 degrees - that's just INSANE. The fish are gonna start dying.

[losthills]

11. Trout are in trouble

from the Appalachians to the Sierras because they don't do well in water that exceeds 60 degrees...

[Stinky The Clown]

12. Holy shit

I don't know what else to say.

[bonito]

13. Gee I wonder

Maybe we can build solarpower watercooling plants.

[BrightKnight]

14. 25k tons of CO2 per day required to offset 1 unit w/ coal

The unit produces about 9,000,000 MWh per year / 365 days = 25,000 MWh per day
Coal = 1 ton per MWh

[amandabeech]

15. A couple of years ago Europe had an extremely hot summer.

The French, who depend heavily on nuclear power, had to shut down reactors because the cooling water was too hot.

Siting of many things will become problematic as Global Warming goes further.

[phantom power]

16. I think it will mostly require increasing the size of the exchangers.

[amandabeech]

17. I hope that you're right.

I think that we're going to need all the non-direct-carbon-emitting electrical power that we can get, including both nuclear and renewables. And lots and lots of conservation and lifestyle changes.

[depakid]

18. "exceeding a 90-degree average over 24 hours."

[skids]

19. What's the safe output temp for reactors these days?

Mainly I want to know if they get thermophotovoltaics or any of the other emerging techs up to decent efficiency whether they'd be a practical alternative to current heat/steam/whatnot engines.

[NNadir]

20. It depends on what you mean.

There are some circumstances where you would want to use the heat to distill water for recovery or places where the waste heat is used for some other purpose.

I think more and more nukes are going to need to move away from rivers, which are dying anyway and to the coast line and inland bays.

Air cooling systems are feasible but expensive.

In any case the number of days under which these types of conditions prevail is still relatively low, although they will become more problematic in the future. Maybe we could run some of those brazillion cellulosic ethanol distilliaries off reduced pressure reactor water, although we nuke types would hardly like to sully the ethical purity of the "renewables will save" crowd.

[skids]

21. What I mean...

Is how hot could a reactor get a fairly large surface area of tungsten and still remain within its safe operational parameters?

Theoretical pre-conversion efficiency of heat-to-light (the solid red line):



They intend to use a GaSb cell. Their PR says they expect it could reach total heat-to-electricity system efficiency between 40 and 50% but I don't know if that factors in a later switch to quantum well cells:


http://www.sc.ic.ac.uk/~q_pv/tpv.html

I also don't know if they intend to put thermoelectrics along the cell cooling path to glean extra power off the waste heat from the first stage (the cooling only needs to keep the cell from overheating, and may only require a heat flux at a rate that might be acceptable to put a few thermoelectric layers between that and the final sink) or whether if they do that figure is included in their total system efficiency estimates.

But in order to drive this off a reactor requires 1000K to 2000K temps at the emitter. I have no idea what temps they drive their current steam/water systems at, and figured you would know (?) Are any of the plants use a liquid metal magnetohydrodynamic ("liquid rotor" or "liquid dynamo" in PR speak) system to date as a first stage, BTW?

[NNadir]

23. Oh. I see.

Most steam reactors use sub supercritical steam, meaning outlet temperatures of less than 650K.

Thermoelectric devices drive most nuclear powered deep space craft such as Cassini, New Horizons, Voyager I and II and the Pioneers I and II.

I don't think the TVA will install all kinds of shit until this event becomes common.

HTGC type reactors could get at this point you are talking about, but I'm not sure there'd be a point if they ran off Brayton cycles and were fitted with secondary steam systems.

[philb]

22. Florida base load plants are being shut back because of warming ocean cooling water

coastal utilities cooling water source temperatures increasing at coal plants.

[donsu]

24. interesting - thanks

nt