Home/blog/An Introduction to Nuclear Energy

This is Part 4 of a paper written about the projected US Energy profile in the year 2050. In this chapter, we take a look at Nuclear fuel as an energy source. This was written in 2010, prior to some of the nuclear accidents that have taken place since. 

History of Nuclear Energy

Following the Second World War, the United States began to invest heavily in nuclear energy to prove that it could be used for commercial purposes. In 1946, the Atomic Energy Commission (AEC) was created by Congress to develop civilian uses for nuclear energy. The first nuclear electricity reactor, the Experimental Breeder Reactor I, generated electric power on December 20, 1951. This success marked the beginning of nuclear as a commercially viable energy source.

Two years later, President Eisenhower delivered his “Atoms for Peace” speech at the United Nations, which underscored his commitment to promoting civilian use of nuclear energy. He said, “It is not enough to take this weapon out of the hands of the soldiers. It must be put into the hands of those who will know how to strip its military casing and adapt it to the arts of peace. The United States knows that if the fearful trend of atomic military build up can be reversed, this greatest of destructive forces can be developed into a great boon, for the benefit of all mankind. The United States knows that peaceful power from atomic energy is no dream of the future. That capability, already proved, is here–now–today. Who can doubt, if the entire body of the world’s scientists and engineers had adequate amounts of fissionable material with which to test and develop their ideas, that this capability would rapidly be transformed into universal, efficient, and economic usage,” (Eisenhower).

President Eisenhower highlighted areas in which nuclear energy could change lives. He said, “A special purpose would be to provide abundant electrical energy in the power-starved areas of the world. Thus the contributing powers would be dedicating some of their strength to serve the needs rather than the fears of mankind.” This commitment to use nuclear to build instead of destroy (as it was used during WWII), aimed at changing global mentalities and serving as an example for other nuclear states. The “Atoms for Peace” speech also touched on President Eisenhower’s vision for a nuclear regulatory agency, the International Atomic Energy Agency (IAEA), which was later established by the UN in 1957.

Domestically, Congress established the Atomic Energy Act of 1954. This bill gave the private sector more access to nuclear technologies for civilian purposes and led to the opening of the first large-scale commercial plant in December of 1957 in Shippingport, Pennsylvania. And in 1959, the Dresden-1, the first nuclear power plant funded entirely by the private sector, commenced operations. Nuclear plants continued to be built, with a surge of contracts in the 1970s surrounding the oil crisis. By the mid-80s more than 100 nuclear power plants were in operation.

In 1979, a large accident occurred at the Three Mile Island plant in Pennsylvania. Although no one was directly hurt by the accident, the US became wary of relying too heavily on nuclear power. The United States has not started construction on a new nuclear power plant since the 1970s. However, recently interest in expanding nuclear power has resurged.

The need for decisive leadership in promoting the safe use of nuclear power is more urgent considering increase climate change concern and lack of energy legislation during the Bush administration. Also, the OECD has failed to establish agreements with emerging economies regarding nuclear proliferation concerns. If the US does not devise a comprehensive plan for increasing nuclear energy in its energy portfolio, it could soon be too late to make a material contribution to climate change risk mitigation. Though no new plants have broken ground, the Browns Ferry Unit One in Athens, Alabama was put back into operation in 2007 after having closed more than a decade before due to a fire. Another US reactor has recently been refurbished and another that was ordered the 70s, the Watts Bar-2, is being completed.

Current Role of Nuclear Energy

Nuclear energy accounts 19.4 percent of United States electricity production and 17 percent of electricity worldwide, (EIA AEO 2010). It has maintained a steady share of electricity generation over the last several decades. Though new plants have not been built for years, the United States has very successfully implemented plant life extension programs that have extended some plant lives up to twenty years longer than expected.

Today in the US, 104 nuclear reactors are in operation. Currently, 17 applications for 26 new reactors have been submitted to the Nuclear Regulatory Commission (NRC). However funding and definite commitment from the companies is far from secure. President Obama’s administration has acted to provide incentives for first starters. On February 16, 2010, President Obama announced $8.33 billion in loan guarantees for two new nuclear reactors at a plant in Burke, Georgia. Reaffirming his commitment to expanding our nuclear energy capacity, he said, “Enhancing America’s nuclear capacity is a critical component of our strategy to develop alternative energies that create jobs and reduce our dependence on foreign oil,” (Obama).These plants could be the first to open ground in over three decades. However, loan guarantees may not alone overcome the high risk of opening a nuclear power plant and uncertainty of construction costs.

Internationally, nuclear energy is a strong force. It plays a variety of roles in the energy portfolios of different countries. Some nations rely very heavily on nuclear power. Currently nuclear provides 77 percent of France’s electricity production. Because it produces the cheapest nuclear energy, France is the largest global exporter of electricity, exporting around 18 percent of its produced electricity. Many developing countries are jumping on the nuclear bandwagon and have been constructing new plants. Globally, 57 plants are under construction, mostly in China, Korea, and Russia, with China accounting for 23 of the 57.

Others, such as Germany and Sweden, have been phasing out their nuclear operations. Germany enacted the Nuclear Exit Law in 2000 to carry through with this phase out. In conjunction with the phase out, the government of Germany has heavily invested in renewable energy sources such as wind and solar. However, recent price volatility of oil and natural gas has lead many German leaders to rethink their strategy, and there is speculation the new administration will delay the phase out.

Resources for Nuclear Energy

The 2003 MIT report commissioned by President Bush recommended a comprehensive local uranium resource evaluation program with the goal of bolstering confidence in public reserves. Although no such program has been conducted, every several years the IAEA and the OECD Nuclear Energy Agency (NEA) have teamed up to produce the Uranium Resources, Production and Demand, commonly referred to as the Red Book. The 2007 “Red Book” update confirmed that known uranium resources are growing faster than demand for resources and that we have at least eighty years of reserves, (MIT 2009, 12)

Australia, Canada and Kazakhstan combined have more than half of the world reserves of Uranium-235, (Lake, Bennet, and Kotek).The US also has abundant resources with 7 percent of world reserves.

How Nuclear Energy works

A process called nuclear fission powers nuclear energy. Uranium is the most often used substance for inducing nuclear fission. Uranium-238 is the most common isotope of uranium, accounting for nearly 99 percent of naturally found uranium. However, Uranium-235 is one of the few materials that can undergo induced fission, (Brain and Lamb, 2). During nuclear fission, a Uranium-235 atom absorbs a low energy neutron. This new Uranium-236 atom then breaks up into fragments, which releases energy in the form of heat. “The decay of a single Uranium-235 atom releases approximately 200 MeV (million electron volts).” Because there are millions of uranium atoms in an atom of uranium, “a pound of highly enriched uranium as us­ed to power a nuclear submarine is equal to about a million gallons of gasoline. The heat energy comes from the fact that the sum of the weights of the fragments weigh less than the original atoms. This difference in masses is converted to energy.  Two or three of these fragments are neutrons, which trigger fission of other Uranium-235 isotopes.

However for nuclear fission to work, uranium must be enhanced to have 2 to 3 percent Uranium-135 atoms.

A nuclear reactor is constructed to maintain a constant rate of fission. Generally enriched uranium is formed into inch-long pellets about the diameter of a finger-tip. The pellets are organized into long rods, which are grouped together into bundles. These bundles are surrounded by water, which acts as a coolant. Control rods help technicians prevent the reactor from overheating by absorbing neutrons. When the control rod is raised out of the uranium bundle, the bundle produces more heat. When the rod is lowered into the uranium bundle, it produces less heat. If the rods are completely lowered into the bundle, the reactor shuts-down.

Other than getting its heat energy from nuclear fission, a nuclear power plant operates the same as a traditional coal-burning power plant. It uses the heat from nuclear fission to heat water into pressurized steam, which in turn drives a turbine generator. Some turbines have a heat exchanger, which is a second loop to convert water to steam. This way, the radioactive stem never contacts the turbine. Sometimes the coolant fluid is carbon dioxide or liquid metals.

The reactor’s pressure vessel is usually housed in a concrete containment vessel, which is housed in a larger steel containment vessel. These precautions are taken to ensure that harmful radiation does not escape from the plant. The steel vessel is then housed within a larger concrete building, which is able to survive an earthquake or a plane crash. The absence of this final container caused the damage at Chernobyl to be so great.

High-level radioactive waste is temporarily stored onsite in steel-lined concrete pools filled with water or in airtight steel or concrete and steel containers. These onsite containers are not meant to be permanent. From here the government has plans to transfer the waste to permanent storage in a deep geological repository. Transporting the radioactive waste to the repository in trains and trucks could be very dangerous to accidents and terrorist attacks.

Low-level radioactive waste is classified as A, B, or C level waste and consists of water purification filters, resins, tools, protective clothing and plant hardware. The NRC regulates all low-level waste and the four domestic facilities licensed to dispose of such waste. Some low-level-waste has beneficial uses such as “electricity and medical treatment and diagnosis, biomedical and pharmaceutical research, and manufacturing,” (NEI, Low-Level Radioactive Waste).

Nuclear Energy Technologies

So far there are four generations of reactors. Early prototype reactors built from the 1950s to the early 1960s were Generation I reactors. Generation II reactors were commercial designs in large-scale production constructed in the late 1960s through the early 1990s. Generation III and Generation IV reactors are only in the R&D stages in the US. Generation III began in 1996 and consists of advanced light water reactors and other systems with inherent safety features. The Generation IV program was launched by the federal government in 1999. These reactors are only in their planning stages. They are smaller scale and are expected to be built commercially in two decades from now. In 2000, the US joined a nine country coalition- Argentina, Brazil, Canada, France, Japan, South Africa, South Korea, U.K., and U.S.- to develop peaceful Generation IV reactors.

The new prototypes are based on three types of reactors. The first of which is a gas-cooled reactor. Only a few have been built. These reactors use gas as a core-coolant. One of these reactors being developed is the pebble-bed modular reactor. One is in construction in China. However, plans for a pebble-bed reactor in South Africa just halted due to financial and technical difficulties.

Inside a pebble-bed reactor are billiard-ball sized “pebbles,” each containing 15,000 uranium oxide particles with the diameter of poppy seeds. Each particle has several high-density coatings, including porous carbon buffer, inner pyrolytic carbon layer, silicon carbide barrier coating), and outer pyrolytic carbon layer. 330,000 of these pebbles plus 100,000 unfueled graphite pebbles are put into a metal vessel surrounded by graphite blocks. The unfueled pebbles are shaped out to control temperature distribution.

These gas-cooled pebble-bed reactors are able to operate much hotter than water-cooled designs of the past (900 degrees Celsius compared to 300 degrees Celsius) and at 40 percent efficiency levels (1/4 better than current light-water reactors). The plants are also about ten times smaller than Generation II plants. In part this is because of a simpler design with fewer subsystems than today’s reactors.

These Helium-cooled pebble-bed plants are touted for having new safety features. As a noble gas, Helium does not react with other materials even when hot. Its fuel elements and reactor core are made of refractory material, which retain their strength at high temperatures, and only degrade above 1600 deg. C. Every minute one pebble removed from the bottom of the reactor core as one is added to the top. It takes six months for a pebble to travel through. Because the system has exactly the right amount of fuel to run, it eliminates excess-reactivity accidents. Afterwards the pebbles are easily put into long-term storage.

The second type of reactor being developed is a form of water-coolant reactor. The Generation IV model is a simplified version of past plants. One American design of this type is the Westington Electric International Reactor Innovative and Secure (IRIS) Concept. The Three Mile Island Accident occurred because of loss of coolant. These Generation IV models make sure that that isn’t possible by putting the entire cooling system within a pressurized vessel. Even if a pipe breaks, there is no loss of coolant, and pressure is better maintained.

Finally, the fast-spectrum (or high-energy neutron) reactor is a design for the far future. Fast-spectrum reactors must be supported by metal coolants, such as liquid sodium or lead. The advantages to using liquid metal coolants are that they have exceptional heat-transfer properties which enhance safety in case of an accident and are less corrosive than water. However, the system can be prone to accidents if the sodium mixes with the water, creating a lot of heat. Lasoo, they cost more than traditional water cooling systems.

The other large technological dilemma going forward is whether the US should invest and incentivize open or closed fuel cycle plants. Open fuel cycle plants are conventional nuclear power plants. They avoid dangerous reprocessing and plutonium production. Open fuel cycle plants are also cheaper and more predictable because they have been built in the US before. Their disadvantage is that the process does not fully utilize the energy potential of uranium. Closed fuel cycle plants, like those being built today in France, can produce 30 percent more energy per uranium input, (Lake, Bennet, and Kotek). They also have the advantage of producing less radioactive waste to store. However, recycling fuel is more dangerous than using raw uranium. And reprocessing produces uranium that could be used for nuclear weapons.

Plutonium-239 can also be used in nuclear fission. If used in the future it could increase energy per kilogram by 150 times conventional uranium power plants, (Lake, Bennet, and Kotek).  However, safety and weapons proliferation concerns are greater with plutonium.

Nuclear Environmental and Safety Considerations    

Nuclear energy releases no greenhouse gases or criteria pollutants. From this perspective, nuclear could be a crucial alternative to fossil fuel powered electricity generation. Perhaps, more than domestically, nuclear could be developing countries’ solution to producing low cost energy without extreme environmental costs. A 2003 MIT report commissioned by President Bush studied what steps would need to be taken to expand US nuclear generating capacity three times, to 1000 billion watts by 2050. If the US followed the report’s suggestions, it would avoid 1.8 billion tons of carbon emissions from coal,(Lake, Bennet, and Kotek).

Uranium mining has the same concerns that other mining has, such as land disturbance and acid rain drainage. Also, radioactive minerals can get in contact with air and water during mining. Often miners use acidic and toxic chemicals. Also, uranium mining produces enormous quantities of waste because many mines have ore grades of less than 1 percent, and low grade ore is energy intensive to mine.

However, developing a solution for storing nuclear waste is the pressing environmental concern of nuclear energy. In the United States all of our nuclear waste is being stored in temporary, on-site concrete or steel containers. In 1987 the Nuclear Waste Policy Act designated Yucca Mountain in Nevada as long-term nuclear waste repository. In 2002, Congress approved the use of Yucca Mountain as a nuclear waste repository, and the Department of Energy submitted a license application for the site in 2008. However, in 2009 the Obama administration blocked the use of Yucca Mountain, declaring that it would not approve the use of Yucca Mountain to for waste storage.

This decision has provoked anger from the states of Washington and South Carolina, who are caught storing most of the nation’s nuclear waste in short-term, aging containers. On April 13, 2010, Washington State filed a ruling against the federal government, citingdepartment’s violation of the Nuclear Waste Policy Act and the Natural Environmental Policy Act by its decision to withdraw the license application. The next day, Secretary of Energy Steven Chu announced the department’s decision to delay closing the Yucca Mountain repository for three weeks while the department and court had a chance to prepare, (Greene).

There are many pros and cons towards using Yucca Mountain as a storage location. Transporting waste to Yucca Mountain is not straight-forward, cheap or entirely safe. Politically, the people of Nevada are against its use. Also, the Basin and Range Province of Nevada is prone to earthquakes. Experts do not fear full-scale quakes at the Yucca Mountain location, but there is a possibility of fractures which could cause water leaking into the storage facilities. Lastly, in the far future, tens of thousands of years down the line, risk models cannot accurately predict of what will happen.

The advantages to using the Yucca Mountain storage facility follow. On-site interim storage can only last so long. The US must find a long-term storage location, and the government has already spent $10.4 billion in researching and preparing Yucca Mountain, (Ward). The area is sparsely populated. The government already owns the land. And risk assessments have concluded that the site with be safe for at least the next 10,000 years, (Wheelwright).

Of course, the use of closed cycle plants could significantly reduce the amount of long-term nuclear waste. However, the benefits of closed-cycle plants do not necessarily outweigh the costs. In addition to financial costs, there are numerous safety risks associated with reprocessing nuclear waste in closed-cycle plants.

Nuclear power has had a great safety track record over the last three decades. However, the United States should lead the way in establishing international safety standards because an accident in one country will affect public attitudes everywhere. The 2003 MIT study also suggested using a probabilistic risk assessment method to analyze the relative risk of nuclear plants. Also, in an age of increased threat of terrorist attacks, nuclear plants are vulnerable targets. The September 11, 2001 attacks heightened concern about nuclear security. In 2002, Congress established the Office of Nuclear Security and Incidence Response under the Department of Homeland Security to prepare for any such attack.

Nuclear Economics

Like wind and solar, nuclear power has high fixed costs but little maintenance costs. Because a new plant has not been built since the 70s, construction costs are uncertain. Also, construction costs have gone up around 15 percent per year over the last decade, (MIT 2009, 6). In addition to rising construction costs, the track record for construction of nuclear plants in the 1980s and 1990s not good. Actual costs ended up far exceeding estimated costs due to delays in construction, high interest rates, and high financing costs. This chart below shows the estimated price of nuclear power compared to traditional fossil fuels.

Though it lags far behind the fossil fuels in terms of affordability, nuclear could become more competitive if a carbon tax or a cap and trade system was imposed, (MIT 2003, 7).

The 2009 Update to the MIT study said “The challenge facing the U.S. nuclear industry lies in turning plausible reductions in capital costs and construction schedules into reality…The risk premium will only be eliminated only by demonstrated performance,” (MIT 2009,8). To account for these risks, the study used a 10% weighted cost of capital versus 7.8% for coal or natural gas.

To reduce the risk, the Energy Policy Act of 2005 actually put incentive in for first-movers (first 6 GWe capacity of new plants). However, this incentive has been unsuccessful in its attempt to spur energy companies to action for several reasons. First of all, the Department of Energy was slow in putting such incentives in place. Secondly, an improper emphasis was placed on renewable portfolio standards (RPS) at federal and state level which don’t include nuclear or coal with carbon sequestration. Finally, increased construction costs have increased the risk of building a new plant. Reducing the risk premium could also make nuclear competitive, potential reducing prices by almost 2 cents/K We-h even without a carbon emissions tax.

Nuclear Energy Security

The nuclear energy security concern with is nuclear proliferation. The 2003 MIT report concluded that the “current international safe-guards regime is inadequate to meet the security challenges of the expanded nuclear deployment contemplated in the global growth scenario,” (MIT 2003, ix). The reprocessing system and transportation to long-term storage repositories present proliferation risks.

At the 2005 G8 Summit, President Bush took a lead role in advancing nuclear security solutions, such as having supplier states offer fuel cycle services to new user states, like Russia to Iran. The US should also take the lead on strengthening the International Atomic Energy Agency and establishing an international nuclear fuel bank. The Obama administration’s commitment to reduce the US nuclear arsenal is another step towards promoting peaceful not violent use of nuclear power.

Nuclear Political Viability

Public acceptance of nuclear power is low but growing. Negative associations with nuclear weapons detract from public acceptance. Also, the accidents in Chernobyl and Three Mile Island went a long way towards making the public wary of nuclear power. However, there seems to be little public awareness of the benefits of nuclear power, such as being carbon free or abundance of reserves. And national politicians have recently come out in favor of major expansions to nuclear power. Reduction in cost could be the necessary trigger for increasing public acceptance. Also, state and federal portfolio standards do not currently include nuclear as a carbon free energy source. If nuclear were included in the renewable portfolio standards state and federal government would have more incentives to direct subsidies and R&D towards nuclear.

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