Shh! Secrets of the Cooling Towers

, director, Nuclear Safety Project | August 25, 2015, 6:00 am EST
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Nuclear Energy Activist Toolkit #62

Go up to almost anyone on Main Street, Anytown, USA and ask them what this picture shows and the most common answer you will hear is “a nuclear plant cooling tower.”

Fig. 1. (Source UCS)

Fig. 1. (Source UCS)

The tall, concrete chimney emitting vapor clouds have become the iconic image for a nuclear power plant.

UCS used the iconic image a time or dozen for the covers of reports about nuclear power safety issues (Fig. 2).

It’s ironic that the image is iconic because the tall, concrete chimney is a more accurate indication of plant age than of plant type. Yes, some nuclear power plants have tall, concrete chimneys. But so do some coal-fired power plants and some oil-fired power plants.

The National Environmental Policy Act of 1969 (NEPA) required, among many other things, that power plants be designed and constructed to lessen the adverse consequences from their operation on the environment. Power plants built before NEPA did not feature cooling towers and used once-through cooling instead. Power plants permitted after NEPA typically had cooling towers to reduce the amount of water drawn from the nearby lake, river, or ocean and to also reduce the amount of thermal pollution discharged from the plants back into those bodies of water. Plants under construction at the time NEPA was enacted may or may not have added cooling towers.

Fig. 2. (Source UCS)

Fig. 2. UCS report covers  (Source UCS)

Secret #1

Cooling towers indicate whether a power plant is pre-NEPA or post-NEPA.

From left to right, the aerial photograph in Fig. 3 shows the Unit 1 reactor at the Nine Mile Point nuclear plant, the Unit 2 reactor under construction at the Nine Mile Point nuclear plant, a cooling tower, and the James A. FitzPatrick nuclear plant in upstate New York.

Fig. 3. (

Fig. 3. (Source: Nuclear Regulatory Commission)

The three reactors did not share the cooling tower—it was used only by Nine Mile Point Unit 2. The Nine Mile Point Unit 1 and FitzPatrick reactors draw water from the lake and discharge warmed water back into the lake. But Unit 2—a post-NEPA reactor—required a cooling tower to lessen the amount of water it pulled from the water and the amount of heat it returned to it.

From left to right, Fig. 4 shows the Unit 1 and 2 reactor containment buildings at the Salem nuclear plant, the reactor building for the Hope Creek nuclear plant, and a cooling tower in southwestern New Jersey. The tower belongs exclusively to Hope Creek, a post-NEPA plant. The two Salem reactors draw water from the Delaware River and discharge warmed water back into it.

Fig. 4. (

Fig. 4. (Source: PSE&G)

Secret #2

Not all cooling towers are tall, concrete chimneys.

Fig. 5 shows the three reactors of Alabama/s Browns Ferry nuclear plant in the foreground and its six mechanical-draft cooling towers in the background. Water from the Wheeler Reservoir is drawn in by the nine circulating water pumps in the lower right, sent through the plant to pick up waste heat produced by the three reactors, passed through the six cooling towers to transfer that heat to the atmosphere, and routed via the canal on the left back around to the intake structure to be re-used by the plant.

Fig. 5.  (Source UCS)

Fig. 5. (Source UCS)

There are two cooling tower types: natural-draft (i.e., the tall, concrete chimneys) and mechanical-draft. Both types transfer heat from water to the air by different methods with the cooled water being reused by the plant.

Distribution pipes carry water that has been warmed to about 130°F in the unit’s main condenser to the natural-draft cooling tower and spray it through an array of nozzles onto fill material located about one-eighth of the way up the 500-plus feet tall tower (Fig. 6). Air enters inlets around the entire base of the tower and flows upward through the fill material. The fill material breaks up the water into as many small droplets as possible to promote contact between air and water, which in turn enhances transfer of heat from the water to the air. The warmed air rises by convection and exhausts from the top of the tower. The cooled water drops into the tower’s basin. Pumps draw water from the basin and send it back to the main condenser to sustain the cycle.

Fig. 6. (

Fig. 6. (Source: Niagara Mohawk)

Mechanical-draft cooling towers, like this broken one at Vermont Yankee (Fig. 7), also have distribution pipes that spray warm water onto fill material for the heat transfer function. But instead of the chimney effect that natural-draft cooling towers use to move air through them, mechanical-draft cooling towers use large fans. At the base of each cylinder in the photograph is a large-diameter fan blowing air upward. Air enters the base of the tower, flows upward through the fill material, passed the fans and out the top. Cooled water drops into the tower’s basin for re-use.

Secret #3

The origin of cooling towers is uncertain.

The photograph shows the stilt-like supports at the base of a natural-draft cooling tower at the Watts Bar nuclear plant in Tennessee. The stilts support the weight of the tall, concrete chimney while promoting air inlet flow.

Fig. 8.  (Source UCS)

Fig. 8. (Source UCS)

Some scholars suspect that ancient people in Great Britain began constructing the world’s first cooling tower long ago, but abandoned the effort when an elder returning from spring break at Borchinton-on-Sea pointed out that power plants had not yet been invented. So, the ancient people left their cooling tower base to befuddle less-ancient people for centuries.

Fig. 9. (

Fig. 9. (Source: Flicker photo by Waaghals)

Bottom Line

Cooling towers have almost nothing to do with nuclear safety.

Cooling towers are typically found at power plants—nuclear and non-nuclear—built after the National Environmental Policy Act was enacted.

Power plants that boil steam to spin a turbine/generator are about 32 to 40 percent efficient; meaning for every 32 to 40 units of electricity put out on the transmission power lines, about 60 to 68 units of waste heat must be dissipated to the environment.

Pre-NEPA, most power plants used water—lots and lots of water—to carry away the waste heat.

Post-NEPA, most power plants used cooling towers to lessen the amount of water they consumed from the nearby lake, river, or ocean. Water is still needed (e.g., to replace the water vapor emanating from the cooling towers, but consumption rate is nearly 90 percent lower.

Cooling towers largely dissipate the waste heat from the main condensers. The main condensers at nuclear power plants have no safety role to play in preventing or mitigating accidents.

It is odd that cooling towers that are widely used at all types of power plants and that have no safety function have become iconic nuclear plant symbols.

Because luck plays a larger safety role at nuclear power plants, future covers for UCS’s nuclear safety reports should feature four-leaf clovers, rabbit’s feet, horseshoes (oriented with the opening upward to hold the luck rather than downward to let it run out), and other symbols of good fortune.

The UCS Nuclear Energy Activist Toolkit (NEAT) is a series of post intended to help citizens understand nuclear technology and the Nuclear Regulatory Commission’s processes for overseeing nuclear plant safety.

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  • Debra Erenberg

    Thank you for all of your work on nuclear safety! If you were moving to an area with a nuclear plant (say, the CT shoreline), how far would you want to be from the plant to feel safe?

    • Unlike proximity with a fossil fueled power plant, proximity to a nuclear power plant has no meaningful safety implications. If you want to “feel” safer, stop driving and flying. Both activities are vastly more dangerous than living near a nuclear power plant. Roughly 40,000 Americans are killed in cars every year.

      In the half century that nuclear has been providing low carbon energy, there have only been three incidents of note: Chernobyl, Three Mile Island, and Fukushima. Only one caused fatalities.Chernobyl was a primitive Soviet era design optimized for weapons production and didn’t even have a containment dome. It killed in total, roughly one tenth the number of people killed in our cars every year. The other incidents caused no fatalities.

      In Japan, a nuclear power plant with containment domes, struck with a magnitude 9 quake and 60 foot tsunami, resulting in not one, but three core meltdowns, caused no fatalities. Imagine that.

      • Garry Morgan

        Actually Russ your comments are a fallacy, particularly this one – “…proximity to a nuclear power plant has no meaningful safety implications.” If that were the case then why are there 2-10-25 mile disaster preparedness zones?
        There have been many deaths and sickness attributed to nuclear power, nuclear fuels and the nuclear weapons industry. You prefer to tell the NEI deceptive line.

        There have been deaths as a result of the nuclear disaster at Fukushima. Unfortunately, there are those in the nuclear industry who attempt deception and facilitate the decline of Human Reliability.

        Indications of sickness and death as a result of radiation exposures, Energy Employees Occupational…Act, involving nuclear industry workers is not all inclusive, and up to 2001 all sickness and death cases related to the nuclear industry were restricted information. The current death and sickness claims reflect 107,846 individual workers with a total of $11.7+ billion paid in claims. Not all of the cases are reflected in the Department of Labor Statistics as that cohort grouping only allows certain employees or their families. http://www.dol.gov/owcp/energy/regs/compliance/weeklystats.htm

        That is just a drop in the bucket. There are many more exposures, sickness, deaths and treatment which are not reflected as to an end prognosis as those medical records are restricted. We will never know the exact numbers in the United States nor anywhere else as government regulators have intentionally covered up the facts.

        Concerning the disaster at Fukushima Japan. The IAEA is complicit in covering up the facts, it is a supporter of the nuclear industry, not a protector of human health and life. Reference – “According to data collected by the Fukushima Prefecture, 2014 saw 1,232 nuclear-related deaths. The two towns with the greatest number of deaths were both near the Fukushima plant: Namie, with 359 dead; and Tomioka, with 291 dead…The term “nuclear-related” means a death that does not result directly from radiation exposure but is caused by a disease later caused by that exposure. Indeed, it is radiation-related diseases — including cancer, tumors and genetic damage — that often cause the bulk of health problems and fatalities in cases of radiation exposure.” Source http://www.presstv.ir/Detail/2015/03/10/401156/Deaths-tied-to-Fukushima-disaster-up-18 source – http://www.news24.com/World/News/Japans-nuclear-related-deaths-rise-by-18-20150310-2

  • Because luck plays a larger safety role at nuclear power plants, future
    covers for UCS’s nuclear safety reports should feature four-leaf
    clovers, rabbit’s feet, horseshoes (oriented with the opening upward to
    hold the luck rather than downward to let it run out), and other symbols
    of good fortune.

    Word of advice; keep your day job. You should consider bringing your four leaf clover when you fly ; ). Luck plays a larger role than what? Your sentence just sort of died there. The cooling tower pictures on the Union of Concerned Scientists and Citizens reports strongly suggest to me that these “experts” were unaware that cooling towers are not unique to nuclear power plants.

    I took some photos of the cooling towers at the unfinished Satsop power plant. Beautiful structures.

    http://www.energytrendsinsider.com/wp-content/uploads/2014/05/SatsopCoolingTower.jpg?00cfb7

  • Garry Morgan said:

    Actually Russ your comments are a fallacy

    Actually, Gary, your comments are a fallacy.

    Garry Morgan continues:

    There have been many deaths and sickness attributed to nuclear power, nuclear fuels and the nuclear weapons industry. You prefer to tell the NEI deceptive line

    I don’t know what this NEI line you refer to is. Your safety argument, like the argument against freeing slaves, is a little behind the times my friend. In light of the overwhelming statistics, the safety argument against nuclear energy has become largely outdated. Look around. Most anti-nuclear energy groups today (including Greenpeace) have begrudgingly ceded that it is one of the safest, if not the safest, forms of energy production we have. That’s why the more defensible cost argument has largely replaced the safety argument in most circles, although the cost argument is also deeply flawed. See graphic below this comment.

    Garry Morgan continues:

    If that were the case [proximity to a nuclear power plant has no meaningful safety implications] then why are there 2-10-25 mile disaster preparedness zones?

    The zones are not necessary. They are there thanks to the anti-nuclear energy groups terrifying the public …half century of low carbon cost effective energy with only three incidents of note on the entire planet Earth, of which only Chernobyl resulted in fatalities.

    It’s a deceit to conflate nuclear weapons with nuclear energy. One has been safely producing gargantuan amounts of affordable low carbon energy for over half of a century …the other is a bomb. Let’s hope you don’t start conflating nuclear medicine with nuclear weapons.

    The tactic of terrifying people by conflating bombs with peaceful energy production evolved as a result of the anti-nuclear weapons activists losing their cause to weapons reduction treaties. It’s why this site “All Things Nuclear” (originally founded by real scientists at MIT to limit the arms race) mixes the two together. Much of our electricity comes from dismantled Soviet weapons, a real-world example of swords to plowshares.

    Garry Morgan continues:

    There have been deaths as a result of the nuclear disaster at Fukushima

    Not from radiation. This is your second deceit. Blaming the “reactors” instead of the tsunami for premature deaths statistically linked to the stress of an evacuation is like blaming the “water” for the roughly 20,000 deaths from drowning instead of the tsunami. Most of the stress and anxiety can be blamed on anti-nuclear groups accepting and passing on misinformation about nuclear energy risk. So, in conclusion, those additional stress related premature deaths are in part the result of anti-nuclear energy groups. The anti-nuclear energy groups have become the bad guys.

    Unfortunately, there are those in the nuclear industry who attempt deception and facilitate the decline of Human Reliability

    What is a “decline of Human Reliability?” This mindset that the nuclear energy industry, unlike all other industries, is somehow partnered with the devil is part of the anti-nuclear energy problem/strategy. No such partnership exists. It’s just another branch of the energy industry.

    Garry Morgan continues:

    Indications of sickness and death as a result of radiation exposures, Energy Employees Occupational…Act

    This is your third deceit.

    Your link to the Department of Energy shows a total of 107,000 DOE employees or their survivors over the last half century have received compensation from excessive exposure to ” …chronic beryllium disease, beryllium sensitivity, or chronic silicosis. ” What is silicosis you may be too lazy to Google?

    Silicosis (previously miner’s phthisis, grinder’s asthma, potter’s rot and other occupation-related names) is a form of occupational lung disease caused by inhalation of crystalline silica dust, and is marked by inflammation and scarring in the form of nodular lesions in the upper lobes of the lungs. It is a type of pneumoconiosis… Silicosis resulted in 46,000 deaths globally in 2013 down from 55,000 deaths in 1990

    What is the primary component of solar panels? Silica sand. You might guess that in half a century that some fraction of the 107,000 DOE employees would also have accidently been exposed to excessive levels of radiation in the making, or transporting of fuel, etc, and you would be right. On the other hand, about 3 million people were killed in car crashes in that time frame with tens of millions maimed for life. Health problems related to uranium mining were for uranium mined for nuclear bombs (not fuel for nuclear energy) prior to nuclear power plants becoming a major source of energy around 1970.

    List of nuclear and radiation accidents by death toll over the last half century on the entire planet Earth:

    https://en.wikipedia.org/wiki/List_of_nuclear_and_radiation_accidents_by_death_toll

    Garry Morgan continues:

    That is just a drop in the bucket. There are many more exposures, sickness, deaths and treatment which are not reflected as to an end prognosis as those medical records are restricted. We will never know the exact numbers in the United States nor anywhere else as government regulators have intentionally covered up the facts. Concerning the disaster at Fukushima Japan. The IAEA is complicit in covering up the facts, it is a supporter of the nuclear industry, not a protector of human health and life.

    None of this is true and I don’t waste a lot of time debating conspiracy theorists.

    Garry Morgan continues:

    The term “nuclear-related” means a death that does not result directly from radiation exposure but is caused by a disease later caused by that exposure.

    No it doesn’t and nobody in Japan will die from radiation related illness due to the Fukushima incident.

    The link you provide above goes to an Iranian news site that contains no sources and this is your fifth deceit. Your quote marks are fake. The article does not say “Indeed, it is radiation-related diseases — including cancer, tumors and genetic damage — that often cause the bulk of health problems and fatalities in cases of radiation exposure.” The article says “Nuclear radiation exposure can cause serious health problems. The first signs of nuclear radiation exposure are nausea and vomiting” which is ridiculous because none of the evacuation stress related deaths involving elderly evacuees included radiation sickness.