The Science of Sustainability

What's Next for Nuclear?

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Despite the accident last year at a nuclear plant in Fukushima, Japan, here in the United States, some policymakers – including President Obama – are pushing to expand nuclear energy as a source of abundant carbon-free electricity.

“To meet our growing energy needs and prevent the worst consequences of climate change, we’ll need to increase our supply of nuclear power. It’s that simple,” said Obama in Feb. 2010, during a press conference at a Maryland nuclear plant.

Work has started on four new multi-billion dollar reactors in Georgia and South Carolina, the first to begin construction in the United States in more than 30 years. But observers disagree over exactly what this means.

“Today, we don’t know if there is a nuclear renaissance,” said Per Peterson, chair of the University of California, Berkeley’s Department of Nuclear Engineering. “That will depend on whether these new plants that are under construction now can be built on schedule, on budget, at a reasonable cost.”

Overall, nuclear energy provides 20 percent of U.S. electricity – far more than all solar, wind and other renewable sources combined. And a recent EPA study shows that in order for the country to reduce its carbon emissions enough to slow down climate change, it will need to boost its nuclear energy production.

But skeptics argue that the country doesn’t need nuclear energy to meet its goals.

“The notion that nuclear is the only option we have to reduce our greenhouse gas emissions is preposterous,” said Ralph Cavanagh, co-director of the energy program at the Natural Resources Defense Council, in San Francisco.

Cavanagh said that cost and risk have pushed utilities around the country away from nuclear energy and towards other renewable energy sources, energy efficiency and natural gas.

California has two nuclear plants, the Diablo Canyon Power Plant, near San Luis Obispo, and the San Onofre plant, near San Diego, which has been closed since Jan. 2012, after problems were found with some of the tubes that carry steam.

Per Peterson, member of the Diablo Canyon Power Plant's Independent Safety Committee, in the plant's turbine room. Photo: Gabriela Quirós.

Prospects for the development of new nuclear plants in the state stalled long ago. The Rancho Seco nuclear plant, in Sacramento, was closed in 1989 after a public vote. And California still has in place a 1976 moratorium on building any new nuclear plants until the federal government creates a permanent site to dispose of nuclear waste.

In California and the rest of the country, nuclear accidents from the past continue to cast a shadow on the technology. The worst one to date happened with a devastating explosion and fire at the Chernobyl plant in Ukraine in 1986, which released radiation across Europe.

Twenty-eight rescue workers died from radiation exposure. Other health effects started to show up a few years later.

“The primary finding so far is an increased risk of thyroid cancer and other thyroid diseases in those who were children and adolescents at the time of the accident,” said Dr. Lydia Zablotska, an epidemiologist at the University of California, San Francisco.

Interview Transcript

The radiation increased the risk of leukemia among the 600,000 workers who cleaned up after the accident.

Researchers predict that the Chernobyl accident will cause 4,000 to 6,000 cases of thyroid cancer and 3,000 to 4,000 cases of leukemia. Fourteen deaths from thyroid cancer have been documented so far. And scientists are still following the population for other health effects that might appear later.

Proponents of nuclear energy say that the risks of an accident should be weighed against the health effects from burning fossil fuels. The American Lung Association estimates 13,000 people die in the United States each year from breathing soot particles from coal-fired power plants.

“The public health and environmental consequences of using fossil fuels are so enormous that they dwarf even the consequences of nuclear accidents,” said Per Peterson. “That said, we need to be moving towards new nuclear energy technologies that do not have the potential to release radioactive materials into the environment.”

Per Peterson and his students at UC Berkeley's Department of Nuclear Engineering are working on a new type of nuclear reactor they say would be safer and cheaper than those operating today.

Today’s nuclear reactors are cooled by water, which can cause problems if a plant loses power. The explosions at the nuclear plant in Fukushima, Japan, following an earthquake and tsunami on March 11, 2011, were brought on by a chemical reaction between water and the metal that protects the uranium fuel.

Steam rises from a reactor at Japan's Fukushima Daiichi nuclear plant, in March 2011. Photo: TEPCO.

“At Fukushima, water reacted with the metal cladding of the fuel to release hydrogen, which ultimately caused explosions,” said Peterson.

And the water inside a nuclear plant can be problematic in other ways too.

“The water pressure built up inside the containment to very high pressures, causing leakage and requiring venting, which released radioactive materials,” said Peterson.

Whether it’s fueled by coal, natural gas or nuclear reaction, the goal at any power plant is to produce heat and turn water into steam. During a May visit to Pacific Gas and Electric’s Diablo Canyon Power Plant, Peterson stood on a hill above the plant’s two dome-shaped structures.

“Below us are the two reactor containment buildings that contain the nuclear reactors that are producing heat and boiling water,” he said. “The steam is going into that large turbine building behind and turning the turbines that turn generators and make the electricity that is going out over our heads into the center of California.”

The Diablo Canyon Power Plant's two nuclear reactors are inside the containment domes. The brown building behind the domes is the turbine room. Photo: Gabriela Quirós.

In the mid-1980s, Diablo Canyon’s two reactors were the last to go into operation in California. Today, they produce 16 percent of Northern California’s electricity, enough to power about 2 million homes.

Nuclear reactions are an efficient way to produce heat. In a nuclear reaction, a particle called a neutron hits the nucleus of a uranium atom. The reaction – known as fission — breaks the nucleus in two and releases heat, as well as more neutrons that go on to create a chain reaction of nucleus-splitting.

Peterson aims to make nuclear plants safer by cooling the reactor’s core – where the nuclear reaction takes place – with a liquid other than water.

“The fluoride salts that we’re developing as coolants boil at extremely high temperatures – above 1,400 degrees centigrade – which means that under the conditions we operate at, they’re always at low pressure,” he said.

To further reduce risk, Peterson proposes storing the fuel inside graphite pebbles, which wouldn’t melt down in an accident.

Per Peterson, chair of the University of California, Berkeley's Dept. of Nuclear Engineering, examines his model of a pebble-bed reactor. Photo: Gabriela Quirós.

The pebbles would also offer another advantage over today’s reactors, said Peterson. In a room at the nuclear engineering department, his students have built a model of the pebble-bed reactor they’re testing. They use colored plastic balls slightly smaller than golf balls in place of the graphite fuel pebbles. And for research purposes, they’ve replaced the fluoride salts with water, which is easier to work with.

The yellow, green and gray plastic balls move through a narrow plastic tank, mimicking the way in which graphite pebbles full of fuel might one day float through liquid fluoride salts in a real pebble-bed reactor. The moving pebbles would be an improvement over current reactors, which have to be closed down every 18 months to bring in fresh uranium rods, said Peterson.

“It takes about 30 days for a pebble to go through the core, before it’s removed, inspected, and possibly reinserted,” he said. “That means you’re continuously replacing the fuel and you don’t need to shut down for refueling outages.”

Peterson’s pebble-bed reactor could be in operation in 20 years, he said.


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Category: Energy, Engineering, Physics, Television, Video

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Gabriela Quirós

About the Author ()

Gabriela Quirós is a TV Producer for KQED Science & Environment. She started her journalism career in 1993 as a newspaper reporter in Costa Rica, where she grew up. She won two national reporting awards there for series on C-sections and organic agriculture, and developed a life-long interest in health reporting. She moved to the Bay Area in 1996 to study documentary filmmaking at the University of California-Berkeley, where she received master’s degrees in journalism and Latin American studies. She joined KQED as a TV producer when QUEST started in 2006 and has covered everything from Alzheimer’s to bee die-offs to dark energy. She has shared two regional Emmys, and four of her stories have been nominated for the award as well. Independent from her work on QUEST, she produced and directed the hour-long documentary Beautiful Sin for PBS, about the surprising story of how Costa Rica became the only country in the world to outlaw in-vitro fertilization.
  • Matthew Swyers

    am disappointed in your unbalanced and somewhat misleading portrayal of nuclear
    energy’s future. Your unequivocal statement that nuclear is an essential part in
    dealing with carbon is not accurate. There is already a plan to do just that
    outlined in the book Carbon-Free and Nuclear-Free: A Roadmap for U.S. Energy
    Policy by Arjun Makhijani. Furthermore, your claim that
    nuclear power is “carbon” neutral is misleading. Many gases contribute to
    climate change, some more potent than CO2. Uranium enrichment also
    produces 88% of the CFC gases emitted from the U.S., a potent global warming gas
    and a significant ozone depleter in the upper atmosphere. Also omitted is any
    discussion of the carbon production produced during the entire nuclear cycle. In your statements about Fukushima you fail to mention the 74
    similarly designed and aging reactors in our country, and the NRC’s irresponsibility
    in re-licensing many of these plants beyond their safe operational lifespan. A
    further even more dangerous problem is the lack of a plan for the 70 years of
    waste that have accumulated, and the much more vulnerable pools of used reactor
    rods. A real comparison of the subsidy disparity between nuclear and other real
    renewables: solar, wind, offshore wave energy and geothermal was never
    mentioned. If the total subsidies lavished on nuclear energy from it’s
    inception had been invested in real renewable energy, we would see a very
    different energy present and future. Nuclear is a dinosaur from a time when
    bigger was better, centralization was chosen over dispersed systems, and fetishism
    with technology trumped appropriate technology in harmony with the biosphere. Nuclear
    has had it’s future and found wanting.

    • Lindsay Dempsey

      Nice to see such an open minded agenda free response to the topic. If I recall correctly Prof Peterson mentioned that we needed to do all these things, and I agree with that position. If we are talking about economically acceptable outcomes, nuclear power is the only workable 'big hammer' solution to driving carbon out of power generation. Renewables can definitely be a part of that and should be there, but not at any price. For technologies like solar and wind they cannot keep the lights on if they are the only generators on the system, they need support from other systems or other generators to maintain a continuous electrical supply at an acceptable price. So let's take a balanced view on these issues, please.

    • Chris Pieronek

      Ooh, "fetishism"! Now there's a word for you–where'd you learn that one, that freshman anthropology class you took back in the mid-seventies?

      You do realize that by throwing around subjective, culturally contingent
      notions like "appropriate technology" and "harmony with the biosphere"
      you're guilty of the very same faulty reasoning of which you (wrongly) accuse
      supporters of nuclear energy? Seriously, think about it–for a little peek at the difficulties involved with the ideas you seem to be trying to articulate, just try coming up with a consistent definition of "nature." You just happen to have a different axe to grind. I am sorry that the blue glow of Cherenkov radiation around nuclear fuel rods does not give you the same warm fuzzies as your backyard composting drum. But that is not adequate reason to shelve the only technologically mature energy source we possess that is cleaner and safer than fossil fuels (in terms of people killed in the US for all time, which is ZERO for nuclear) and can be readily deployed on the same scale.

      Fortunately, my generation understands this. After Fukishima, there was a demonstration in front of the nuclear engineering building here at Berkeley: there were about ten people there for an hour or two, all with gray hair and looking to be in their sixties. And that brought to mind the words of the great Max Planck: "A new scientific truth does not triumph by convincing its opponents and making them see the light, but rather because its opponents eventually die, and a new generation grows up that is familiar with it." The future's going to be okay. But probably not for the reasons you'd think.

  • Raul Parolari

    Very interesting post, Gabriela. I add this: fluoride salts are not only usable as "coolant", but also as "Fuel". This was proven in the '60s, by Alvin Weinberg and its "Molten Salt Reactor" (MSR). Unfortunatley, that research was shut down (by the Nixon administration in 1973) as the choice was the Plutonium Breeder reactors (the MSR did not produce Plutonium).

    The extraordinary news is that the Chinese Academy of Sciences has invested 350 million dollars to build both a liquid molten salt "Cooled" reactor and a liquid Thorium molten salt "Fuelled"reactor (dates: 2017 for the first one, 2020 for the second). They have placed on the project more than 400 scientists and engineers. And the DOE (Us dept of defense) and the University of Berkeley are participating in the project.

  • David

    Thanks Gabriela, the Japanese picked up an Iodine 131 in October 2011, the french believe that the experimental sodium reactor melted down just north of Beijing….back to the drawing boards boys…..

    If anyone is contact with the the 400 scientists or engineers in China, perhaps you could recommend liposomal vitamin c to help clean up some the damage to their cells….

  • marimbadearco

    I cruise around KQED and fine a pro-nuclear power article. Where are the spent fuel rods going to go? where are the many produced now? why isn't this up front?
    Look at this biased sentence:

    "Overall, nuclear energy provides 20 percent of U.S. electricity
    – far more than all solar, wind and other renewable sources combined.
    And a recent EPA study shows that in order for the country to reduce its
    carbon emissions enough to slow down climate change, it will need to
    boost its nuclear energy production."

    1. of course the EPA happens to be strongly, to put it mildly, pro-nuclear: THEY are the only source here?

    2. look how this is written. Solar and wind have been starved for decades, only getting some decent funding in the last few years. If you are going to compare nuclear with "all solar, wind and other renewable sources combined", then include how much GOVERNMENT INVESTMENT has gone into each. What do you think the ratio has been over the last 4 decades? and beyond?

    This is kind of pro-corporate stenography that has residents in the still very polluted Gulf calling NPR National Petroleum Radio.