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Power Science

Heat Wave Shuts Down Alabama Reactor 401

Posted by CowboyNeal
from the weathering-the-heat dept.
mdsolar writes "In a first for the US, one of three nuclear reactors at the Browns Ferry nuclear plant in Alabama has been shut down because the Tennessee River is too hot to provide adequate cooling for the waste heat produced by the reactor. This is happening as the TVA faces its highest demand for power ever, reports the Houston Chronicle. This effect has been seen in Europe in the past, forcing reduced generation, but the US has until now been immune to the problem. The TVA will buy power elsewhere and impose higher rates, blaming reduced river flow as a result of drought."
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Heat Wave Shuts Down Alabama Reactor

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  • by Anonymous Coward
    As for a while, they were planning to use one engineer's idea of cooling it with ice cold beer.
  • by davidwr (791652) on Saturday August 18, 2007 @11:15AM (#20276187) Homepage Journal
    In Soviet Russia, overheating nuclear reactor [wikipedia.org] shuts down YOU!
    • by cluckshot (658931) on Saturday August 18, 2007 @02:46PM (#20278445)

      A little noted fact of the cold war is that a very large amount of the US total electrical generation capacity is in the TVA region (Tennessee River - Dependent) The loss of this reactor is serious as the whole USA has no reserve capacity at peak load and with the heat wave over the East USA this is a critical loss. If it were the only reactor in danger this might be of no concern. The US TVA operates 5 big reactors and numerous coal fired plants all of which have the Tennessee River at thermal capacity to cool them and the river is dropping daily.

      If heavy sustained rain does not fall on the Tennessee River Valley over the next 3 to 4 months an event which is historically unlikely, the loss of something close to 15 times the Browns Ferry reactor in capacity is likely to hit the USA. There is nothing to pick up the load. The loss of this one reactor is nearly equal to all the wind energy the USA generates. This loss threatens the operations of every one of the 48 US States. With the possible loses in Alabama Power pools and their reactors etc as well as Georgia Power, this poses the very real risk of cutting the energy supply of the USA by a very large fraction. As I write the North Alabama region is short 60 inches of rain over the past 18 months. The US TVA has been drawing down storage for 5 years now. There is no reserve and little prospect of one for some years to come.

      I had warning of this imminent event when the City of Huntsville requested from TVA more water for its treatment plant and was turned down for supply. I knew then that the supply was gone.

      • by yusing (216625) on Saturday August 18, 2007 @10:04PM (#20282089) Journal
        Huh. Gosh. See, if we'd invested in a MIX of power instead of depending so heavily on coal and nuclear (which the industry is trying to bump up in significance), we wouldn't be facing such a predicament.

        Germany has wisely seen fit to invest one-seventh of its power money in wind energy. And it has legislated, and many Germnans have benefited for years already, from a solar-energy subsidy.

        Too bad we don't have uncorrupted, uncronyed leadership in the US with the courage and vision to diversify the energy portfolio. Pay now or pay MUCH MUCH more later.

        Nuke-lovers are always griping that wind-energy is too unreliable. Huh, guess what?
        • Re: (Score:3, Insightful)

          by UbuntuDupe (970646) *
          Too bad we don't have uncorrupted, uncronyed leadership in the US with the courage and vision to diversify the energy portfolio

          What do you call the energy futures market?
        • by Ecks (52930) on Sunday August 19, 2007 @01:25AM (#20283357)
          TFA has the engineering wrong. The problem isn't the river temperature as much as the air temperature. A nuclear power plant needs to be located near a river so it can have a large supply of relatively cool water to use as a working fluid. The river water gets boiled into steam by reactor water in the nuclear reactors primary coolant loop. This is steam is what turns the turbines and generates the electricity. When it exits the turbines it's still steam, it's just cooler and wetter. You can't return it in this state because doing that would dramatically raise the river's temperature. You have to cool it down before you can put it back. To do that you use a passive air to water heat exchanger. But they're having a heatwave down there. Between the starting temperature of the river and the reduced efficiency of the passive heat exchanger using all three reactors in the plant would heat the river to unacceptable levels.

          Unacceptable is not boiling it's probably something in low 90F range because if the mean temperature of the river was over 90F for any period of time you raise the risk of algae blooms and fish kills.

          Physical conditions are not preventing the plant from running, environmental considerations are. And if the river's temperature is close to or exceeds the contracted discharge temperature without being heated by the plant then reevaluating the environmental decision may be in order.

          -- Ecks
        • Using this to impeach nukes is profoundly wrong.

          I'm in favor of alternative, renewable energy sources, but each source has varying degrees to which it is useful in particular situations for technology and production cost reasons. (For example, many places just don't make a good wind farm - and some places make an extremely mediocre and very expensive one.) I think we're going to have a bloom of much better solar at some point, but there's definitely still some room for improvement there.

          I'm also certainly
  • not immune (Score:4, Insightful)

    by thhamm (764787) on Saturday August 18, 2007 @11:16AM (#20276191)
    >but the US has, until now, been immune to the problem.
    no, not immune. it just hasn't happend until now.
  • Reasons right? (Score:5, Informative)

    by Anonymous Coward on Saturday August 18, 2007 @11:18AM (#20276209)
    I work at a nuclear power plant. We have a limit for the temperature of the river downstream of our returned cooling water for environmental reasons, not reasons related to the power generation process. I suspect the TVA has a similar requirement.

    I noted from the nrc website (www.nrc.gov) that their other reactors are operating at reduced load, which is what our reactors must do to limit the heat input into the river.

    So this is nothing remarkable.
    • Re:Reasons right? (Score:4, Interesting)

      by Toad-san (64810) on Saturday August 18, 2007 @11:31AM (#20276341)
      I see those huge cooling towers and water cooling systems .. and I have to wonder ...

      How efficient is a power generation plant that throws away gigawatts of power as waste heat?

      Isn't it about time you find a more efficient way to generate power, turbines and generators that don't waste so much heat that we just went to all that trouble to make in the first place?

      I don't expect 100% efficiency, but what we're doing now is crazy.
      • Re:Reasons right? (Score:5, Informative)

        by Wonko the Sane (25252) * on Saturday August 18, 2007 @11:45AM (#20276469) Journal
        Physics: It's not just a good idea, it's the law [wikipedia.org].
        • by Colin Smith (2679) on Saturday August 18, 2007 @12:12PM (#20276735)
          To heat domestic water, space heating and even to power adsorption chillers which can reduce AC requirements. Even coal power stations can hit 88% efficient.

          http://www.helsinginenergia.fi/en/tuotanto/benefit s.html [helsinginenergia.fi]

          US power stations are still only 40% efficient because ... Well you decide for yourself.

           
          • You are just playing word game with the definition of "efficient". There is a fundamental limit of how much work can be extracted by heat flow between two temperatures.

            I would expect a country with a colder climate to be able to extract more work out of a nuclear reactor. Those super-efficient reactors won't do so well with a 90 Fahrenheit cooling medium
            • by Colin Smith (2679)

              You are just playing word game with the definition of "efficient".
              No. I am not. It's energy used for a useful purpose.

              There is a fundamental limit of how much work can be extracted by heat flow between two temperatures.
              And extracting work isn't the only use for heat...

               
          • That works great assuming that you're close enough to a power plant so that it makes economic sense to dig a tunnel full of big fat steam pipes to your house. Unfortunately, only a tiny fraction of the population lives that close.
            • Re: (Score:3, Informative)

              by Colin Smith (2679)

              Unfortunately, only a tiny fraction of the population lives that close.
              Not necessarily the case.

              In Denmark they have a truly *huge* "district heating" network.

              e.g.
              http://www.dbdh.dk/ [www.dbdh.dk]

               
              • by Waffle Iron (339739) on Saturday August 18, 2007 @12:50PM (#20277087)
                That's because so many people in Denmark are close enough to a power plant to run steam tunnels to their locations. The trend in the US over the past decades has been to build huge power plants in the middle of nowhere, so it just wouldn't work here.

                Recently, a new trend has been to build smaller cogeneration facilities in populated areas in the US, but due to valid political and environmental concerns, the only viable fuel for these is natural gas. That fuel is already in short supply and dwindling fast, so that's not going to solve the problem by itself.

          • by fabu10u$ (839423) on Saturday August 18, 2007 @02:56PM (#20278565)

            Some people sell their "waste" heat
            To heat domestic water, space heating and even to power adsorption chillers which can reduce AC requirements.
            Try selling the US public on steam heat from a nuke. Yes, the coolant loop neither touches the core nor picks up radioactive ions, but see if you can get the unwashed masses to believe they'll be safe with it!
        • by timeOday (582209)

          Physics: It's not just a good idea, it's the law.

          Oh brother. It's past time for a Godwin's Law [wikipedia.org]-style rule about thermodynamics on slashdot. Every time [google.com] somebody propses conserving wasted energy, somebody else retorts that perpetual machines are impossible or something to that effect.

      • Re:Reasons right? (Score:5, Informative)

        by hankwang (413283) * on Saturday August 18, 2007 @11:48AM (#20276517) Homepage

        How efficient is a power generation plant that throws away gigawatts of power as waste heat?

        From the heat source to electrical power output is usually in the range 35--50%, depending on the plant design. A fundamental problem is the theoretical limit of the efficiency of a heat engine, a device that converts a temperature difference into mechanical power. It is 1 - Tcold/Thot, where Tcold and Thot are the temperatures of the cold and hot parts, in kelvin. For a steam-operated heat engine, the cold end is around the boiling point of water (373 K), and the hot end might be 1000 K, which limits the efficiency to 63% if there are no other losses. But one can use the waste heat for other purposes in a cogeneration plant [wikipedia.org], for example for residential heating in cold climates or for the industry.

        • by Colin Smith (2679)
          The "waste" heat can power adsorption chillers in hot climates.
           
      • Re:Reasons right? (Score:4, Informative)

        by Cyberax (705495) on Saturday August 18, 2007 @11:49AM (#20276519)
        Nope. You can't beat http://en.wikipedia.org/wiki/Carnot_cycle [wikipedia.org] in efficiency. The practical upper limit for nuclear power plants is about 50%. And we're already getting closer to this limit.

        We can use some insane things like high temperature (thousands degrees) reactors with gas cooling to get another 10%-15% of efficiency, but it is just not practical.
        • We can use some insane things like high temperature (thousands degrees) reactors with gas cooling to get another 10%-15% of efficiency, but it is just not practical.

          Never, ever, ever dismiss that sort of technique (i.e. engineering problems) as "not practical". It may not currently be a good business decision under the evaluation rules being used by the management at a particular company, but that doesn't mean that a significant performance improvement that requires new techniques isn't a viable (and essen

      • by turgid (580780)

        Isn't it about time you find a more efficient way to generate power, turbines and generators that don't waste so much heat that we just went to all that trouble to make in the first place?

        There is a British design called the AGR [wikipedia.org] which operates at thermal efficiencies of up to 40% compared with 30-33% in a PWR (what they used in the USA). The thing is, it's terribly expensive and no more will ever be built.

        As another poster has already stated, look up the Carnot Cycle to learn about thermal efficiency of

      • Especially considering the coming energy crunch.

         
      • Heat is disorganized motion, right? Atoms and molecules just bumping around any which way. If you want organized motion, which is useful energy -- such as an organized motion of electrons, a.k.a. electricity -- then you have to get that heat motion organized, flowing in one direction.

        You do this by making the heat flow from one place to another. But here's the catch: you need a source and a sink to have a flow. The hot reactor core is the source. The river is the sink. Heat flows from the former to th
    • by mdsolar (1045926)
      According to the article, this is different from environmental requirements on the down stream temperature. This is a lack of cooling capacity problem. The the energy transfer rate for the waste heat is just not high enough with the river temperature at 90 F.
      --
      Better electricity: http://mdsolar.blogspot.com/2007/01/slashdot-users -selling-solar.html [blogspot.com]
      • by TheLink (130905)
        Sounds strange to me.

        In other countries it's usually because the water _released_ will be too hot. I bet the reactors could take water in as long as it's liquid, release steam and not blow up, but the stuff in the river won't be happy.

        90F is pretty cold compared to the temperatures the turbines run at, not even comparing the reactor core. I'd thought the safety margins would be higher.

        If the river has too little water, then it's a bigger problem.
        • The temperature inside your condenser is always higher than temperature of the water you send back into the river.

          The temperature of your condenser is directly related to the pressure of saturated steam/condensate mixture. Higher temperatures correlate to higher pressures in the condenser.
          1. Condensers are only designed to withstand a certain amount of pressure
          2. The work your turbine can produce is directly proportional to the difference in pressure between the steam supply and the condenser.
      • Re:Reasons right? (Score:4, Informative)

        by Dachannien (617929) on Saturday August 18, 2007 @12:15PM (#20276759)
        Actually, if you really do read the article carefully, nowhere does it state that the water itself is incapable of cooling the reactor. It merely states that the river water is "too hot", which could just as well indicate that adding more warm water - especially in drought conditions where the river level is probably lower than normal - would make the river temperature too hot to safely sustain its ecosystem.

    • Yeah the big question to me is what other options are there for cooling a power plant other than using river water, and are they more sustainable / resilient to climate change? I don't think that underground cooling would be sufficient. I looked at how some of the desert plants operate and they too use running water - from the sewage lines of "nearby" cities, which is treated before use in the plant and then returned for reuse.

      Seeing as how nuclear is really the only option we have for decreasing our power-
  • by MMC Monster (602931) on Saturday August 18, 2007 @11:18AM (#20276219)
    Why not just run the river through a refrigerator to cool it down? After all, you can generate the electricity for the refrigerator in the plant.

    (I'd patent the idea, but the patent office has a silly rule regarding perpetual motion machines that gets in the way...)
    • Re: (Score:2, Informative)

      by Anonymous Coward

      Why not just run the river through a refrigerator to cool it down? After all, you can generate the electricity for the refrigerator in the plant.

      Actually, it would be quite possible to do such a thing and you wouldn't even violate the second law of thermodynamics since you are only pumping the heat. One example of such a mechanism is the electrically powered fan on radiators in cars that improve cooling when the car is not moving.

      However, it wouldn't change the problem: Where to dump the waste heat. Inste

  • by Anonymous Coward
    This is not that unusual for power plants. Some coal fired units are off as well, for example Dynegy's Wabash River is currently experiencing similar problems. Obviously this hurts everyone (the company loses generation during times when wholesale power prices are high and, if load gets too high, the consumer might experience brown outs or black outs). This problem will likely get worse as well as global warming takes hold.
    • by FooAtWFU (699187)
      By what mechanism will global warming make rivers sooooo much warmer? I mean, I'm hearing about projections that say it will be about half a degree (C) warmer by 2030.....and, mapping this directly to the river as well, I just doubt that this sort of pathetic little increase in water temperature is enough to prevent the proper operation of their reactor (or its compliance with environmental regulations limiting how hot their cooling processes are allowed to make the river). Do you propose an alternative mec
  • To anyone arguing that Climate Change is actually a good thing - in general, it isn't, and this is an example. Especially in the US, our entire infrastructure, agriculture and manufacturing is built and created under the assumption that things will stay the same. Pipelines in Alaska were built under the assumption that permafrost was, well, permanent. Nuclear reactors were built under the assumption that the temperature changes of rivers are known and won't change. Levies are built with certain assumptions
    • Um...isn't this the nature of time, life, existence, et cetera? Things change. Even if there were no such thing as man-made global warming, the Sun would still vary its output, the continents would continue to drift, evolution would continue to produce new and interesting diseases, et cetera and so forth.

      What do we call individuals who run their lives under the assumption that things will always stay the same? That they'll never get old or sick, that their job will never disappear or their skills become
  • by mdsolar (1045926) on Saturday August 18, 2007 @11:34AM (#20276377) Homepage Journal
    The cooling problem is a result of TVA's interest in building more reactors. Browns Ferry is now operating with two reactors instead of three because they recently added a reactor. They are also planning on adding a reactor upstream at Watts Bar http://www.tva.gov/news/releases/julysep07/wbu2.ht m [tva.gov] adding to the heat load on the Tennessee River. So, next time, they may have to take two Browns Ferry reactors off line at seasonal peak demand. This makes electricity more expensive because it requires buying rather than selling electricity when it is most expensive.

    But, the fairly natural solution to the problem, reducing summer demand through net metering of customer generated solar power, a solution being implemented in 41 states and DC, is hampered in the TVA service territory by TVA's net metering policy: http://www.tva.gov/purpa/net_metering.htm [tva.gov] which is a billing period-by-billing period policy rather than an annual carryover policy used in net metering states. Adopting a reasonable net metering policy would allow TVA to become a summer time peak demand power exporter and gain by arbitrage, reducing the risk of higher overall rates it is building for itself by not paying attention to the capacity of the river system to handle the 60% of wasted energy nuclear power generation creates.
    --
    Power when you want it most: http://mdsolar.blogspot.com/2007/01/slashdot-users -selling-solar.html [blogspot.com]
    • by b0s0z0ku (752509)
      Can't they use air cooled condensers (aka cooling towers) rather than using river water to cool the steam directly? River water is only one way to cool a power plant.

      -b.

      • Almost always the river water is cooler than the air temperature and has a much larger specific heat capacity. If the plant was modified to run completely on air cooling, it would be far less efficient 99.9% of the time,
        • by b0s0z0ku (752509)
          If the plant was modified to run completely on air cooling, it would be far less efficient 99.9% of the time,

          But nonetheless, there are air cooled plants that were designed as such and work just fine.

          As far as river water, yes on the higher specific heat, but no on it being almost always cooler than the air -- in winter, it's normally warmer. A static body of water will have the same year around average temperature as the air, but the instantaneous temperature will lag the air temperature due to the he

          • A static body of water will have the same year around average temperature as the air, but the instantaneous temperature will lag the air temperature due to the heat capacity of the water.

            Not true; besides the effect of snow melt you mentioned there is the effect of evaporation which keeps the river cooler that the ambient air on average.
      • by mdsolar (1045926)
        Cooling towers are usually part of the design of a power plant, but they need to be run hot enough to to get a good energy flow rate and cool enough so that steam is properly condensed. Final cooling is usually handled by the river or tidal system. Apparently what is happening here is that the cooling towers can't do the last stage. More cooling towers might help but this increases costs so looking at other options for power generation becomes important.
        --
        A better way: http://mdsolar.blogspot.com/2007/ [blogspot.com]
  • River's too hot to adequately cool their equipment, yet they're...

    blaming reduced river flow as a result of drought.
    Curious, no?
    • by mdsolar (1045926)
      The drought in the southeastern US has not yet been conclusively linked to global warming. The problems described in Europe have been linked. It takes time to get that stuff figured out and it was not until the most recent IPCC report (this year) that the heat wave deaths in Europe were strongly linked. The main problem is that TVA is overloading the capacity of the river system as it is by over reliance on nuclear power so that it is increasing costs for rate payers.

      Because nuclear power involves such
  • by fantomas (94850) on Saturday August 18, 2007 @11:50AM (#20276529)
    Interesting in the article that the journalist doesn't include power generated by hydroelectric dams as renewable energy...

    "TVA gets about 60 percent of its electricity from coal-fired power plants, 30 percent from nuclear plants and 10 percent from its 29 hydroelectric dams. Renewable energy sources such as wind and solar account for less than 1 percent."

    Any idea why that might be? Political slant? ignorance?

    Umm, I mean the water flows through the dam, it goes out to sea, it evaporates, and it rains back up in the mountains and comes through the dam again. Seems pretty renewable to me.... at least some of it is coming back up through that cycle if not all...

    • Interesting in the article that the journalist doesn't include power generated by hydroelectric dams as renewable energy...

      Journalists ain't scientists, and scientists ain't journalists... in general. So if you're reading something in the news that's science related, don't count on it being accurate.
    • Re: (Score:3, Informative)

      by belg4mit (152620)
      It's renewable in some sense, but not others. More specfically, big hydro genereally ends up not being sustainable:
      fish spawning, methane, changes to the microclimate. On the other hand, we've not done enough with run-of-river.
      • Re: (Score:3, Informative)

        fish spawning, methane and changes to the micro climate don't effect the dam's ability to generate electricity, so it is still renewable energy.
        Renewable != earth loving hippy compatible.
  • It sounds like its time for the nuclear industry to do some testing of the atmospheric vortex engine (see slide 18 (warning PowerPoint) [vortexengine.ca]:
    • delivers the performance of a $60 million natural draft tower at the cost of a $15 million mechanical draft tower
    • eliminates need for fans, saving 1% of the energy produced by a power plant
    • eliminates need for tall chimney, saving 2/3 of the capital cost
    • replaces conventional cooling towers
    • delivers the heat to the upper atmosphere where it radiates into space
    • solves probl
  • by tetrahedrassface (675645) on Saturday August 18, 2007 @01:21PM (#20277459) Journal
    I have supported the restarting of Browns Ferry Unit 1 for a long time. Because despite the issues nuclear power is an immediatly available and fairly clean power source. Browns Ferry Unit 1 has had a bumpy road to travel since it was commissioned, and then shut down, and then restarted. Since its restart it has contributed clean energy at a time when the Tennessee Valley has been hammered by record high temperatures.record rainfall deficits that have severely curtailed hydroelectric production and made for conditions calling for record power demand levels.

    One occurance that also recently occured at Browns Ferry [wate.com]was the automatic shutdown of the reactor due to a coolant leak. TVA reported to the NRC that an unknown amount of reactor cooling water had indeed leaked and they spent last weekend repairing it. After restart the high water temps forced this shutdown. In fact this is nothing new though. We had the Sequoyah reactor [tva.gov]using its cooling towers last year due to elevated water temps.

    But yeah its been hot for sure. Also of interest is it looks like we are going to get the newest reactor in the US and that it be at Watts Bar [nrc.gov]. Unit 1 has been online there since 1996, and produces enough juice for 250,000 homes. Unit 2 at Watts Bar was roughly 80% complete when construction stopped. TVA is currently and exploring finishing the construction of Unit 2 giving us yet another clean power source. In September 2000 Watts Bar Unit 1 set a record for continuous operation of TVA reactors of similar design.
  • Actually... (Score:3, Informative)

    by danwesnor (896499) on Saturday August 18, 2007 @09:07PM (#20281647)
    The reactor was shut down because the water exiting the plant's cooling system exceeded an average of 90 degrees F over a 24 hour period. The plants have an agreement with the state to limit the temperature of the water they put into the river. The water in the river is not even remotely 90 degrees F.

    Brown's Ferry also just recently started one of its reactors after a long downtime, so this only kicked us back a few months. It's not a big impact to the nation's grid, not even to the local area.

    As for why we don't recapture the energy in the heated water to make even more power, well, they just didn't think it was necessary back when we used to build power plants back in the 60's. Investing money in anything nuclear in the US is political suicide.

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