Callaway II and Nuclear Power: Separating Fact from Opinion
A conversation with Turk Storvick, MU Professor Emeritus of Chemical Engineering
[This interview with Prof. Storvick is intended to clarify some of the questions that we should be asking about building a second nuclear plant in CallawayCounty. Dr. Storvick favors nuclear power, but the following questions and answers are not intended for advocacy. The purpose is to give all of us some basic information so we are in a better position to make judgments for ourselves.]
If a second reactor (Callaway II) were built, how would it differ from Callaway I?
Callaway I was built using 1960s science and 1970s technology. Callaway II would be built using third-generation nuclear reactor technology. This new technology incorporates many passive safety features to reduce the opportunities for human error. An American subsidiary of the French firm AREVA is designing Callaway II using the newest Generation Three pressurized water technology. AREVA has built or is building over 100 nuclear plants around the world and is currently designing four plants similar to Callaway II in the United States.
How would the electrical output of Callaway II compare to Callaway I?
Callaway I produces 1000 megawatts for the electrical grid plus about 200 megawatts to run the plant itself. Callaway II would produce an additional 1600 megawatts for the grid. The power produced by Callaway II would be sufficient to power about 1,000,000 homes. A newly built coal plant could produce a comparable amount of power.
How much fuel does a nuclear plant use and how does that compare with a coal plant?
Callaway I uses 6-7 pounds of fuel (uranium) per day. Callaway II would use about 10-12 pounds per day.
A coal plant would use 12,000 tons of high-grade coal per day to produce the same 1000 megawatts of power as Callaway I. Consider that one railroad car of coal holds about 100 tons, so a 120-car train would be required daily to fuel a comparable coal plant. Most of the coal for Missouri’s coal plants is mined in Wyoming and transported to Missouri in unit trains.
Where do we get the uranium for reactors?
Most uranium is mined in the US, Canada, or Australia. Natural uranium extracted from the mined rock contains about 0.7% uranium, which must be enriched to 3-5% for use as nuclear fuel.
Another source is to reprocess spent nuclear fuel. France has reprocessed the fuel from its reactors. The US has experimented with this technology, but has not built a commercial application. Reprocessing also addresses the storage problem of spent fuel from reactors. The spent fuel contains 95% of the energy of the original fuel, providing another strong incentive for reprocessing.
How is spent fuel stored?
Spent fuel is stored in what looks like a huge swimming pool, about three times the size of the Olympic pool at the MU recreation center. The Callaway I pool is about 35 feet deep, and contains all the spent fuel since the Callaway plant began producing electricity in 1984. A similar pool would be built for Callaway II and could hold all spent fuel for 50 years. The life of the spent fuel pool would obviously be greatly extended if the spent fuel were reprocessed.
What about emissions?
A nuclear plant uses water for cooling and the only emission from the cooling tower is water vapor. Callaway I evaporates about 16,000 gallons of water per minute from the Missouri river, which is first purified to remove sediment.
A coal plant producing 1000 megawatts would produce approximately 26,000-30,000 tons of carbon dioxide per day. The emissions are scrubbed, but some nitrogen oxides, sulfur dioxide and mercury are released. Interestingly, almost all coal contains some uranium and the fly ash remaining after burning the coal contains more uranium by weight than would be needed to fuel a nuclear plant producing the same amount of electricity.
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If You Want to Get More Technical…
Prepared by T. Storvick
April 13, 2009
Why is there such a big difference in the energy produced by:
- a ton of coal (burned) in a power plant and
- a few ounces of uranium (fission) in a nuclear reactor?
For comparison:
Callaway I is rated at 1,000 megawatts of electricity, generating 24 million kilowatt hours per day.
Nuclear:
The source of the energy difference between coal and nuclear is in the structure of an atom. Let’s visualize an atom as a small, “fuzzy ball.” All atoms are composed of three particles: electrons, protons, and neutrons. The center or core of an atom (the nucleus) is very small and contains all the protons and neutrons. The nucleus represents nearly all of the mass (weight) of the atom because the mass of the electrons is also very small. The “fuzz” of our atom represents the electrons in constant (very rapid) motion close to the nucleus. An atom is about 25,000 times larger than the tiny nucleus. The protons and neutrons in the nucleus are held together by a very short-range “strong force” (strong force is the technical term since we don’t know how to describe it) that holds the nucleus together. When an atom of uranium fissions (splits its 92 protons into two pieces, with each piece forming a new atom that we call “fission products”), there is a huge repulsive force that releases about 200 million eV (an electron volt is an energy unit per atom – like calories per gram assigned to energy in food). Six or seven pounds of uranium atoms that fission in a reactor will produce the 1,000 megawatts of electricity in a plant such as Callaway. You’ll have to trust a scientist to do this calculation!
Coal:
Most of the energy released from coal comes from burning the coal’s carbon. When one atom of carbon combines with two atoms of oxygen (burning), about 4.5 eV of energy are released. The change in the arrangement of the “shared electrons” going from carbon to carbon dioxide produces energy. The difference in energy release between the fission of uranium and burning of carbon is the reason for the huge difference in the amount of fuel needed.
Coal contains many elements in addition to carbon, so it is best to compute the tons of coal required to produce 1,000 megawatts per day of electricity. The Energy Information Administration (U. S. Government statistics on energy) reports that about half of the electricity produced in the U. S. was produced by coal in 2006. The United States burned 1.3 billion tons of coal to produce 1.99 billion megawatt hours of electricity in 2006. Extrapolating from these data, a coal-fired power plant would require 12,300 tons of coal per day to produce the 1,000 megawatts of electricity that the Callaway I plant produces when six pounds of uranium fission.
Fuel Supply:
Specialists say the U. S. has enough coal to last between 200 and 450 years. Compare this estimate to the uranium metal that has been mined and extracted from uranium ore since 1940. Currently, about 70,000 tons of uranium in spent fuel is stored at the 104 nuclear reactors sites in the U. S. Spent nuclear fuel is about 95% uranium and it can be recovered by chemical processing. About 450,000 tons of uranium remains from the “enrichment” process used to make domestic nuclear fuel. There may be 100 to 500 tons of excess military uranium and weapons grade plutonium, both of which can be processed to make nuclear fuel. With new reactor designs (Generation IV reactor systems) and estimating that one half of this uranium might be available to be processed into nuclear fuel, the United States potentially has the fuel to produce all of the electricity used today for about 1,500 years without further mining of uranium.
Nuclear fuel is not the issue. Investing in spent fuel reprocessing technology and installing advanced design nuclear reactors would make it possible.