Alternative Energy. Editor: K Lee Lerner, et al., 2nd Edition, UXL, 2012.
Introduction: What is Nuclear Energy?
Nuclear energy is energy that can be released from the nucleus of an atom. There are two ways to produce this energy, either by fission or fusion. Fission occurs when the atomic nucleus is split apart. Fusion is the result of combining two or more light nuclei into one heavier nucleus. Most often, when people discuss nuclear power, they are talking about nuclear fission. Power production from fusion is still in its infancy.
Atoms are made up of several parts: Protons and neutrons bound together within a nucleus, and electrons bound to the nucleus, but outside it. A nucleus is the positively charged center of an atom. Protons are positively charged particles, and neutrons are uncharged particles. Electrons orbit around the nucleus and are negatively charged.
Fission can occur in two ways. First, in some very heavy elements, such as rutherfordium, the nucleus of an atom can split apart into smaller pieces spontaneously. With lighter elements, it is possible to hit the nucleus with a free neutron, which will also cause the nucleus to break apart.
Either way, a significant amount of energy is released when the nucleus splits. The energy released takes two forms: light energy and heat energy. Radioactivity is also produced. Atomic bombs let this energy out all at once, creating an explosion. Nuclear reactors let this energy out slowly in a continuous chain reaction to make heat, which is then used to produce electricity. After the nucleus splits, new lighter atoms are formed. More free neutrons are thrown off that can split other atoms, continuing to produce nuclear energy. The first controlled nuclear reaction took place in 1942.
Nuclear fission
Since at least the 1920s, scientists had believed that it might someday be possible to produce energy by splitting atoms. They based this belief on their growing understanding of the physics of the atom. They knew that atoms contain energy. These scientists believed that by “splitting” the atom, or breaking it apart, they could release that energy. The process would come to be called nuclear fission.
As stated earlier, an atom is made up of three kinds of particles: neutrons, protons, and electrons. Two of these particles, neutrons and protons, are found in the nucleus, or center, of an atom. A neutron does not have an electrical charge. It is called a neutron because its electrical charge is neutral. A proton has a positive electrical charge. Circling around the nucleus of an atom in layers are electrons, which have a negative electrical charge. To keep the overall electrical charge neutral, an atom has to have the same number of protons and electrons.
Positive and negative electrical charges attract each other. Within an atom, the electric charges bind the electrons to the positive nucleus, which is positively charged due to its protons. Inside each nucleus, protons and neutrons are bound very tightly to one another by what is called the “strong nuclear force.” When an atom is split, some of this binding energy within the nucleus is released.
The atoms of different elements have different numbers of particles. Some elements are very simple and light. Hydrogen is the simplest and lightest element because it has only one proton, one electron, and, for the vast majority of hydrogen atoms occurring naturally on Earth, no neutrons. (Deuterium and tritium are “isotopes” of hydrogen, and respectively have either one or two neutrons residing next to the single proton.)
In contrast to hydrogen, the heaviest element occurring naturally on Earth (at least in any significant quantity) is uranium. (Some heavier elements have been artificially produced in laboratories, but these elements do not normally exist on Earth.) Uranium atoms contain 92 protons and 92 electrons. The number of neutrons can vary, depending on the isotope of uranium under consideration. An isotope is a “species” of an element. It contains a different number of neutrons from other isotopes of the same element. Generally, uranium nuclei contain either 143 or 146 neutrons.
For nuclear energy, uranium is the most important element. Uranium is used as fuel to produce nuclear reactions. It makes a good fuel source because uranium atoms are so big and heavy. They are easier to break apart. These large atoms can be thought of as a house built with playing cards. The house becomes increasingly unstable as cards are added. It is more likely to fall apart the bigger and heavier it gets. In a nuclear power plant, the goal is to create fission from uranium fuel and to be able to speed the reaction up (or slow it down) to control the amount of energy being produced.
Historical Overview: Notable Discoveries and the People Who Made Them
Scientists such as Enrico Fermi (1901-1954) noticed that the free neutrons released by radioactive decay in elements such as uranium bombard other uranium atoms. This bombardment causes the other atoms to split and release additional neutrons. These additional neutrons then bombard other atoms. The process continues in a chain reaction, or a reaction that keeps going on its own. A neutron in this way can be thought of as similar to a cue ball on a pool table. The cue ball bombards the cluster of balls at the other end of the table, causing the cluster to break apart. All the balls then bounce around, bumping into one another, causing further collisions, and so on.
Fermi had conducted experiments in nuclear fission in 1934 while he was still living in Rome, Italy. He had bombarded uranium with neutrons and discovered that what was left were elements that were much lighter than uranium. This led him to believe that the uranium atoms had been split. The mass number of the leftover elements was smaller, so the uranium must have transformed into different elements as it broke down.
In 1938 German scientists Otto Hahn (1879-1968) and Fritz Strassman (1902-1980) conducted a similar experiment. They discovered that what was left over after bombarding uranium with neutrons was the much lighter element barium. This experiment confirmed that the uranium atoms had split.
Other scientists such as Lise Meitner (1878-1968) from Austria and Niels Bohr (1885-1962) from Denmark achieved similar results. But they also made a startling discovery. When the atomic weights of the by-products of their experiment were added together, something was missing. If every piece of a broken window is swept up and weighed, the total weight of the pieces should be the same as the weight of the original window. Scientists expected that the same principle would apply to atoms. If atoms broke down because of fission, the atomic weight of the new elements formed, when added together, should be the same as the atomic weight of the original uranium.
However, Meitner and Bohr found that the elements in the reaction lost mass. Some of the mass had changed to energy. In this way they proved the truth of the famous equation from Albert Einstein (1879-1955), E = mc2. This equation says that energy (E) is equal to mass (m) multiplied by the speed of light (c) squared. Mass, or matter, could be converted into energy.
None of these experiments produced a chain reaction, or a continuing fissioning of atoms. However, in 1942 Fermi thought of a way to create such a chain reaction. He took 40 tons of uranium, a nuclear “pile,” and surrounded it with 385 tons of graphite blocks to contain the uranium. (A “pile” of nuclear materials is not literally a pile in the sense of being a heap or mound of something. Instead, as used here “pile” refers to a quantity of nuclear materials arranged to form a nuclear reactor.) This would provide him with the “critical mass” needed to produce an ongoing atomic reaction.
Fermi’s main concern was to make sure that the reaction did not get out of control. A controlled chain reaction produces a flow of energy, but an uncontrolled chain reaction produces an explosion (but not necessarily a nuclear explosion, or nuclear bomb—stringent conditions must be met before an actual nuclear explosion is produced). Fermi needed a way to make sure that he did not create a disaster by letting his planned reaction get out of control. The graphite blocks would help, but he also inserted rods made of cadmium, a soft bluish-white element, into the pile. Cadmium absorbs neutrons, so it can keep nuclear fission reactions under control.
On the afternoon of December 2, 1942, Fermi and his team slowly pulled a few of the cadmium rods out of the pile. Now some of the spontaneously released neutrons in the uranium could bombard other uranium atoms. Each collision produced two or three free neutrons (for an average of 2.5 neutrons per collision), which in turn bombarded other atoms, releasing on average 2.5 more free neutrons, and so on. More rods were slowly pulled out, and the pace of the reaction increased. When rods were pushed back in, the reaction slowed as the cadmium soaked up neutrons. Fermi had created the world’s first nuclear reactor.
From the Manhattan Project to Atoms for Peace
Fermi conducted his successful experiment almost exactly one year after the Japanese attacked the U.S. naval base at Pearl Harbor, Hawaii, on December 7, 1941. This attack pulled the United States into World War II. The war actually began in September 1939 in Europe, when German dictator Adolf Hitler (1889-1945) ordered his troops to invade Poland. In the years that followed, Germany occupied much of Europe. Meanwhile, the Japanese empire was spreading throughout Asia and the Pacific.
Most of the leading scientists involved in nuclear research were from Germany. U.S. policymakers learned that German scientists were trying to develop an atomic bomb, a bomb whose enormous destructive force would come from an uncontrolled fission reaction. Such a bomb in the hands of Germany could have changed the outcome of the war. Thus, American policymakers developed a plan for the United States to create such a bomb first. This is the reason for the secrecy surrounding the message informing the government that Enrico Fermi’s experiment had been successful.
The research program to develop the bomb was called the Manhattan Project. (The name Manhattan has no particular meaning. The branch of the army that oversaw the project was based in Manhattan, New York.) Beginning in 1943, the nation’s top scientists, many of them from top-ranked universities, gathered in Los Alamos, New Mexico. Physicist J. Robert Oppenheimer (1904-1967) directed the research. The scientists worked in shacks and lived in primitive conditions, all the while keeping their work top secret.
Continuing the research of Fermi and others, the scientists succeeded in building an atomic bomb, which they tested in the New Mexico desert on July 16, 1945. By this time, though, Germany had surrendered and the war in Europe was over. However, the war continued to rage in the Pacific as the United States and its allies fought a determined Japanese empire. During the final months of the war with Japan, both countries lost large numbers of troops in bloody island battles, such as those on the Japanese island of Iwo Jima. The Japanese were defeated, but refused to surrender.
The United States sought a quick end to the war. Ultimately, the country decided to drop an atomic bomb on the Japanese city of Hiroshima on August 6, 1945, followed by a similar bomb on Nagasaki three days later. Together, the two bombs instantly killed more than 100,000 people. Many more would later die as a result of burns and radiation sickness. Additionally, the Soviet Union attacked Japanese forces in Manchuria on August 9, having just declared war on Japan late the previous day. Faced with the destructive capability of the American nuclear bombs, as well as the Soviet attack and declaration of war, Japanese Emperor Hirohito (1901-1989) announced the surrender of Japan on August 15, 1945.
The decision to use the atomic bomb was highly controversial. Many U.S. policymakers urged use of the bomb as a way to save the lives of U.S. soldiers as well as Japanese troops and civilians, who faced the possibility of massive casualties in a planned Allied invasion of Japan. Others, including many nuclear scientists, believed that using the bomb would cause too much destruction and death, especially among the civilian population. Many believed that it was just a matter of time before Japan surrendered.
After the Soviet Union developed its own atomic weapons, the world’s two superpowers began to stockpile them. Each country accumulated far more nuclear weapons than would ever be needed to defeat the other side. In the 1950s and beyond, the world lived in fear that a nuclear war would erupt, with devastating consequences. Many scientists, though, searched for peaceful ways to use nuclear energy.
On December 8, 1953, U.S. President Dwight D. Eisenhower (1890-1969) addressed the United Nations. In his speech, he outlined the “Atoms for Peace” program. He suggested that atomic development and research be turned over to an international agency and that research be conducted to find peaceful uses for atomic energy. This speech gave a major push to efforts to harness atomic energy for the benefit of humankind rather than as a weapon.
Atomic energy development
Those efforts had already begun in the United States. In 1946, the government created the Atomic Energy Commission. Its job was to oversee the development of nuclear power. One of its first steps was to authorize the development of Experimental Breeder Reactor I in Arco, Idaho. On December 20, 1951, the reactor produced the world’s first electricity fueled by nuclear power, lighting four 200-watt lightbulbs. On July 17, 1955, Arco, home to 1,000 people, became the world’s first town to be powered by nuclear energy.
Until this time, nuclear energy had been firmly under the control of the military. The first civilian power plant began operation in Susana, California, on July 12, 1957. The world’s first commercial-sized nuclear power plant reached full operating power in 1957 in Shippingport, Pennsylvania. (Most nuclear power plants, for safety reasons, operate at about 70 to 90 percent of their maximum capacity.) Meanwhile, on July 14, 1952, the keel had been laid for the world’s first nuclear-powered submarine, the U.S.S. Nautilus. On March 30, 1953, the sub powered up its nuclear generators for the first time.
Nuclear power developed rapidly in the late 1950s and into the 1960s. On October 15, 1959, the Dresden-I Nuclear Power Station came online (that is, began to operate) in Illinois. This was the first nuclear power plant to be built entirely without money from the government. On August 19, 1960, the Yankee Rowe Nuclear Power Station in Massachusetts became the nation’s third nuclear power plant.
On November 22, 1961, the U.S. Navy commissioned the U.S.S. Enterprise, the world’s largest ship. Powered by nuclear energy, the aircraft carrier could operate at speeds up to 30 knots for as far as 400,000 miles (643,738 kilometers) without having to refuel.
Another milestone was passed on December 12, 1963, when the Jersey Central Power and Light Company launched construction of the Oyster Creek nuclear power plant. The Oyster Creek plant became operational in 1969. This was the first nuclear power plant to be ordered as an economic alternative to a fossil-fuel plant. In 2010, the company that operates the Oyster Creek plant announced that it would be shut down in 2019, marking some 50 years of service by that time.
By 1971 the United States was operating 22 nuclear reactors that provided 2.4 percent of the nation’s electricity. By the end of the 1970s, 72 reactors were producing 12 percent of the nation’s electricity. And by the end of the 1980s, 109 reactors were generating 14 percent of the nation’s electricity. These numbers peaked in 1991, when the number of reactors rose to 111, together supplying about 22 percent of the nation’s electricity. By the early 1990s, nuclear power plants were generating more power in the United States than all power sources combined generated in 1956. From the early 1990s through 2010, nuclear power in the United States averaged about 20 percent of the nation’s electricity output.
Similar developments were taking place worldwide. As of 2010, 430 nuclear reactors produced 2,630 billion kilowatt-hours of electricity in 31 countries. The United States led the way with 104 nuclear reactors operating within 65 nuclear power plants spread across 31 states. However, due to the country’s size, that amount of power provided only 20 percent of the nation’s electricity output. The nation that generated the highest percentage of its electricity needs from nuclear power was France, at about 74 percent. After France, the countries with the highest proportion of nuclear electricity production in 2010 were Belgium, Slovakia, and Ukraine, with each country meeting about half its electricity needs with nuclear power.
Setbacks
In the 1950s and 1960s, scientists around the world believed that nuclear power had unlimited potential. Along with most of the public, they believed that nuclear plants would provide an endless source of cheap, renewable, clean energy. The 1980s saw a dramatic rise in the construction of new nuclear power plants. That decade saw 218 new commercial reactors begin service, which averaged out to about one new reactor coming online somewhere in the world every 17 days!
The new reactors included 47 installed in the United States, 42 in France, and 18 in Japan. In 2011, more than 60 new commercial reactors were under construction in 15 nations, but only two of those were in the United States. The two U.S. reactors under construction were the Watts Bar 2 reactor, located in Tennessee, and the Bellefonte Unit 1 reactor in Alabama. It was anticipated (in 2011) that the Watts Bar 2 reactor would commence commercial operations in 2013, while the Bellefonte Unit 1 reactor would begin operations between 2018 and 2020. When construction of the Watts Bar 2 reactor is completed, it will be the first new reactor (as opposed to an existing, refurbished reactor) in the United States since 1996. In early 2012, the Nuclear Regulatory Commission approved the construction of two new reactors in Georgia.
The electricity produced by nuclear power worldwide in 2010 amounted to around 14 percent of total world electricity production, which was less than the 16 percent that nuclear power contributed in 2005. The nuclear energy industry seemed to be stagnating. However, due in part to concerns about greenhouse gas emissions and the availability and rising costs of fossil fuels, more nations were considering increased use of nuclear power. According to the World Nuclear Association, in mid-2011, there were plans to build 154 nuclear reactors worldwide, with an additional 343 reactors proposed for construction.
Safety Concerns
Starting in the late 1970s, and continuing into the early 2010s, public apprehension about the safety of nuclear power escalated. Those doubts initially arose with the industry’s first major setback, which took place on March 28, 1979. On that day an accident occurred at the Three Mile Island nuclear power plant near Harrisburg, Pennsylvania. No one was injured or killed, and no one was overexposed to radiation from the plant. Still, the accident forced the plant to shut down.
If plant workers had failed to contain the accident, a meltdown could have occurred. (“Meltdown” refers to an out-of-control reaction that overheats the reactor, causing it potentially to melt into the earth below, releasing radiation into groundwater and the atmosphere.) Many Americans started to distrust nuclear power, believing that the possibility of a catastrophe was too great.
Fears were stoked when a major Hollywood film was released that year called The China Syndrome. The movie dramatized events at a fictional California nuclear power plant that were eerily similar to the Three Mile Island accident. Its title referred to the theoretical possibility that an overheated nuclear reactor could melt its way through the earth to China.
In 1986, a major disaster struck. On April 26 an explosion took place in reactor number 4 at the nuclear power plant in Chernobyl, a city in Ukraine (formerly part of the Soviet Union) about 70 miles (112 kilometers) north of Kiev. In this accident, a large amount of radiation was released into the atmosphere. Scientists estimate that the amount of this radiation was 100 to 150 million curies. (Although the curie unit is well known by scientists and engineers, the becquerel is now the standard unit of radiation.) The radiation was primarily in the form of radioactive cesium and iodine. Thirty-one people were killed in the immediate aftermath of the incident, including firefighters, and 135,000 people within a 20-mile (32-kilometer) radius had to be permanently evacuated.
Several years later, an additional 110,000 people were evacuated. Entire villages had to be decontaminated. Radioactivity spread over large areas of the Soviet Union, into Eastern Europe, and as far away as Scandinavia. It is estimated that the accident cost the Soviet Union $12.8 billion. The human costs—stress, lost homes, poor health—cannot be fully measured. The governments of Belarus, Ukraine, and Russia—the three countries most affected by Chernobyl’s radioactive fallout—have reopened some of the land that was previously closed to human habitation and agriculture. However, according to the International Atomic Energy Agency (IAEA), around 3,861 square miles (10,000 square kilometers) of land in those three countries will remain “substantially contaminated” for decades beyond 2010. These substantially contaminated areas, which will require ongoing monitoring of their radiation levels, will remain dangerous for people to live in, as well as for crops and farm animals.
Various organizations have attempted to accurately determine any diseases caused by Chernobyl’s radioactive fallout. For instance, the World Health Organization (WHO) issued a report in 2011 marking the 25th anniversary of the Chernobyl disaster. The report relied on information from a variety of scientific studies to reach conclusions about the negative health effects caused by the radiation released from Chernobyl. Scientists with the WHO found that the rates of thyroid cancer for people who were 18 and younger at the time of the incident were considerably higher in the parts of Belarus, Ukraine, and Russia that were most contaminated by radioactive fallout.
In addition, researchers estimate that several thousand cases of thyroid cancer have resulted from the radiation released in the 1986 disaster. Other ill health effects, such as increases in other types of cancer or increased birth defects, could not be supported by the results from scientific studies. However, since some cancers (such as leukemia) can take decades to develop, WHO scientists assert that more diseases may eventually be attributed to Chernobyl’s radiation.
Despite such tragedies, the use of nuclear power to replace fossil fuels (such as coal) for the large-scale generation of electricity continued to be advocated by many people. By the start of the 2010s, the memory of the Chernobyl and Three Mile Island disasters had faded for much of the general public. Furthermore, the election of Barack Obama (1961- ) in 2008 meant that greater attention would be paid to greenhouse gas emissions than had been the case with the previous administration of George W. Bush (1946- ). Since the use of nuclear power in place of fossil fuels can help reduce greenhouse gas emissions, many advocates for nuclear energy had hoped that the Obama administration would expand the use of nuclear power plants in the United States.
However, on March 11, 2011 a massive earthquake and tsunami hit Japan. The tsunami, which killed many thousands of people outright, caused extensive property damage. Severe damage claimed many homes, farms, businesses, and other facilities, including the Fukushima Daiichi Nuclear Power Plant complex located on the east coast of Japan.
The Fukushima Daiichi power plant (also called Fukushima 1 since “Daiichi” means “number one” in Japanese) contains six nuclear reactors. The reactors are labeled 1 through 6. At the time of the tsunami, reactors 5 and 6 had been shut down for maintenance work. Reactor 4 was also not operational at the start of the disaster. Reactors 1 through 3, however, were up and running when the earthquake struck. Even though the magnitude 9.0 earthquake triggered the automatic shutdown of the three operating reactors, and auxiliary diesel generators then began supplying electricity to run the power plant, the subsequent tsunami swamped the entire Fukushima 1 complex, flooding many buildings, as well as the diesel generators.
All power to the Fukushima 1 power plant was lost. Within a few days of the tsunami, all three reactors (1, 2, and 3) that had been operational were in full meltdown. The buildup of hydrogen gas in several reactors resulted in explosions when the hydrogen was ignited. Fire swept reactor 4. The disaster halted production of the considerable amount of power that the Fukushima 1 plant had previously produced—some 4.7 gigawatts (4,700 megawatts) of electrical power.
Radiation leaks from the damaged Fukushima 1 complex spurred the evacuation of many tens of thousands of people living within 12.5 miles (20 kilometers) of the nuclear power plant. Due to the radioactive contamination, people may not be allowed to return to live in the evacuated area for decades.
Within days after the reactor meltdowns, measures were taken to cool the damaged reactors by using fire trucks and helicopters to douse the reactors with water. In the weeks that followed the plant’s shutdown, workers reentered the nuclear complex to try to restore power for pumps and other essential equipment, as well as put out any remaining fires. The workers who returned to the plant were volunteers. These people all understood that they were risking death from acute radiation poisoning, since radiation levels in and around the damaged reactor cores were very high. Workers rotated in shifts at the Fukushima plant, but were unable to enter the buildings housing the nuclear reactors due to the high radiation readings.
In early April 2011, about three weeks after the disaster started, the bodies of two young men were found in the nuclear complex. They had been employed at the plant and their deaths were attributed to the tsunami. As of early 2012, no deaths due to radiation poisoning had been reported either inside the nuclear plant or outside it, in the rest of Japan. However, some workers at the crippled nuclear plant received excessive doses of radiation during cleanup operations.
The efforts to gain control of the disabled reactors at Fukushima continued throughout 2011. Workers were finally able to enter one of the buildings housing a disabled reactor on May 5, 2011. By that date, approximately 2.91 million gallons (11 million liters) of seawater had been pumped into reactor 1 alone in order to cool it. Leaks of radioactive particles and water from the damaged reactors continued throughout the summer of 2011 as workers made slow, but steady, progress in containing and cooling them.
By late September 2011, a milestone was reached when all three damaged reactors at Fukushima achieved temperatures below 212°F (100°C)—a condition known as a “cold-shutdown.” Despite such progress, the complete cleanup of the Fukushima complex is going to be a long-term process. In November 2011, Japan’s Atomic Energy Commission announced a plan to remove all of the radioactive fuel from Fukushima’s damaged reactors by 2021. The commission further stated that the effort to completely decommission (clean up) the entire Fukushima complex could take 30 years (that is, until 2041).
After the disaster at Fukushima 1, the Japanese government shutdown many of its nuclear power plants in order to carry out safety inspections. The loss of nuclear power for electricity generation prompted the Japanese to import much more liquefied natural gas (LNG) in order to make up the shortfall in the country’s energy needs.
In June 2011, estimated costs for dealing with the Fukushima disaster were announced. Costs included compensating the people evacuated from their homes due to radiation contamination, as well as the costs of permanently closing the plant’s reactors. The estimates were produced by different organizations, and ranged from a low of $71 billion, all the way up to the highest estimate of $250 billion.
These accidents burst the nuclear industry’s bubble. People began to fear a major accident that would dwarf the kinds of accidents that took place at conventional coal-fired. electric-generating stations. In the aftermath of the Fukushima nuclear disaster, for instance, public sentiment in Germany turned decidedly against nuclear energy. Bowing to public opinion, the German government announced in May 2011 that all of the nation’s nuclear power plants would be decommissioned by the year 2022. This action was taken in spite of the fact that in 2011 nuclear power supplied nearly a quarter of Germany’s total electrical power.
Other Concerns
The nuclear industry began to face other problems from the 1980s and beyond. The cost of building nuclear power plants was spiraling out of control. Most new plants went far over budget. This trend continued with a new generation of power plants being built in the early 2010s.
A prime example can be found in France. In July 2011 the French utility company EDF announced delays and cost overruns in its effort to add a third nuclear reactor at the site of an existing nuclear power plant in Flamanville, France. The new reactor—with a power output of 1,650 megawatts—constitutes an updated reactor design called the European Pressurized Reactor (EPR). The new reactor was originally slated to cost around $5 billion and begin operation in 2013. The announcement of July 2011 projected final costs of $9 billion, with a new operational date of 2016.
In the 1980s and 1990s, the first aging nuclear plants had to be shut down and taken out of operation. It was discovered then that the cost of decommissioning (shutting down) a nuclear power plant was high because extreme care had to be taken to dispose of radioactive components properly.
On top of these problems, the radioactive waste from nuclear power plants was beginning to accumulate, often at the site of each nuclear plant. In the United States, wrangling over where to dispose of the nuclear waste meant that there was no agreed-to solution in sight, even by the start of the 2010s.
Because of these problems, plans for construction of new plants were canceled in many cases. Nuclear power had become an emotional issue. Its supporters believe that by the year 2050, the energy needs of the United States will triple. They believe that other forms of alternative energy can help, but only nuclear plants can provide power on a sufficiently large scale. Opponents of nuclear power, however, believe that its costs and inherent risks are too high.
Despite of opposition to nuclear power, the nuclear industry continues to play a prominent role in supplying America’s energy needs. According to the U.S. Energy Information Agency (EIA), in 2010 about 20 percent of U.S. electrical power was provided by 65 commercial nuclear power plants. Those 65 nuclear power plants housed a total of 104 licensed nuclear reactors. There are more reactors than power plants because some plants contain more than one nuclear reactor. For instance, the Fukushima 1 Nuclear Power Plant, disabled by the March 2011 earthquake and tsunami, contained six separate nuclear reactors.
The U.S. Government Accountability Office (GAO) released a report in 2011 stating that all U.S. nuclear power plants have caused some degree of groundwater contamination due to leaks of radioactivity. In many cases, leaky underground pipes at the nuclear plants were to blame. Unless preventative steps are taken, the corrosion of pipes and other equipment at nuclear power plants can be expected to increase as America’s nuclear plants continue to age. The GAO recommended that government officials do more to monitor the condition of pipes and other equipment at nuclear plants, as well as develop technologies to prevent leaks and other failures in the future.
How Nuclear Energy Works
Generating electricity through nuclear power is an enormously complex technical feat. It takes the combined skills of geologists (scientists who study Earth’s structure, especially rocks), mine operators, engineers, and scientists, as well as large numbers of highly trained and skilled plant operators. The federal government oversees the construction and operation of these plants to make sure that they are built and operated to the very highest standards.
Uranium
Producing nuclear power begins with the fuel, uranium. Uranium was discovered in 1789 by German chemist Martin Klaproth (1743-1817). He discovered uranium in a mineral called pitchblende. The element was named after the planet Uranus, which had been discovered just eight years earlier. Scientists’ best guess is that the naturally occurring uranium found on Earth was formed in supernovas (or exploding stars) about 6.6 billion years ago. In the earth, radioactive decay of uranium is the planet’s main source of internal heat.
Uranium is used primarily in the nuclear industry, but it has other uses as well. Because it is a dense, heavy element (18.7 times as dense as water), it is sometimes used in the keels of boats as a weight to keep them upright. (Density refers to weight relative to volume. A ton of feathers weighs as much as a ton of lead, but because lead is denser than feathers, it takes up far less volume.) Uranium’s density also makes it useful as a counterweight in such applications as airplane rudders, and it makes a good radiation shield.
So-called “depleted uranium” (DU) is used by the U.S. military as well as the militaries of many other countries. Depleted uranium—which has a much lower proportion of the radioactive isotope 235U than naturally occurring uranium—is usually obtained from the processing of uranium for fuel in nuclear reactors, or for use in making nuclear bombs. DU emits about 40 percent as much radiation as naturally occurring uranium.
Uranium’s exceptionally high density and relative abundance has made it a good material for penetrating tough materials such as armor, and it is also incorporated into armor for protecting military vehicles. However, the use of DU in military applications has its critics since it still possesses some radioactivity that can constitute a long-lasting, hazardous material on battlefields. In some weapons systems, depleted uranium has been replaced by dense, strong materials such as tungsten. In 2009, Belgium became the first country in the world to ban the use of DU for military applications. However, many nations, including the United States, continued to use DU in military systems in the early 2010s.
The uranium atom
Uranium is relatively abundant, and it is the heaviest naturally occurring element on Earth since it has the highest atomic number (92 protons). (Plutonium actually has a higher atomic number—94 protons—than uranium and can be also be found naturally on Earth, but only in extremely trace amounts.)
Uranium has 16 different isotopes, although the most common ones are 235U and 238U. 234U is found in trace amounts and results from the decay of 238U. The more abundant isotope, 238U (which accounts for 99.3 percent of the uranium in Earth’s crust) plays a role in keeping the earth warm.
Like any radioactive substance, 238U decays, but it decays very slowly. Its half-life is about the same as the age of Earth, 4.5 billion years. (“Half-life” is a term scientists use to refer to the rate at which a radioactive substance decays, or breaks down. Thus, half of all of Earth’s 238U has broken down over the past 4.5 billion years. Half of the half that is left will break down over the next 4.5 billion years, and so on.) From the standpoint of nuclear energy, the important isotope of uranium is 235U.
The nucleus of a 235U atom consists of 92 protons and 143 neutrons. This is the isotope of uranium whose atoms can be split relatively easily. When a 235U atom is struck by a neutron, the atom splits, releasing energy. It also releases two or three neutrons of its own, which in turn split other atoms, and on and on in a chain reaction.
In a nuclear reactor, the released energy is at first kinetic energy. Kinetic energy is the energy contained in anything (such as water, wind, or a neutron) that is in motion. But the submicroscopic neutrons and other decay products in a nuclear reactor travel only tiny distances, so the kinetic energy is rapidly converted to heat (similar to the way the brakes on a car get hot when they stop the kinetic energy of a moving car). This heat is then used to produce steam, which turns a generator to produce electricity. Heat makes up about 85 percent of the energy released. Most of the rest of the energy is in the form of gamma rays. A gamma ray is a photon similar to visible light, but of much higher frequency (and therefore of much higher energy). Gamma rays are often released by a radioactive substance. Photons, including gamma rays, possess energy but not mass.
In many respects, the process as described is much more complex. For example, physicists note that only isotopes with an odd number of particles in the nucleus, like 235U, are fissile (able to be split). Further, not every neutron that hits a uranium atom causes fission. Sometimes the neutrons are absorbed by the atoms they strike, so no fission takes place. Other neutrons simply escape and do nothing. Another complication has to do with the speed of the neutrons. Some are called “prompt neutrons,” but others experience a delay of up to 56 seconds.
The challenge for nuclear engineers is to keep the ongoing fission reaction in precise balance. When the reaction is in balance, scientists say that it has reached “criticality.” At criticality, the neutrons are doing their work in balance, meaning that their numbers remain constant and under control. The pace of the reaction can be speeded up or slowed down by increasing or decreasing the number of neutrons. If the increase is too rapid, the reaction can almost instantaneously get out of control.
Plutonium
Named after the planet Pluto, plutonium (chemical symbol Pu) is an element that forms in a reactor core as the isotope 239Pu. It forms when 238U, which is also present in nuclear fuel, absorbs a neutron. Now the atom has an odd number of particles in the nucleus, making it fissile (capable of sustaining a nuclear reaction) in the same way that 235U is fissile. Both 235U and the artificially produced 239Pu can split apart (fission) when impacted by a neutron. However, both isotopes sometimes just absorb a neutron. In the case where 239Pu absorbs a neutron, the isotope 240Pu can be created; but 240Pu is not a fissile isotope of plutonium (meaning that it cannot directly sustain a nuclear fission reaction.
Over time, the amount of 240Pu builds up in the fuel rods. When the rods are “spent,” meaning no longer usable as fuel, this plutonium (which includes the 239Pu and 240Pu isotopes, as well as other plutonium isotopes) can be recycled. The spent nuclear fuel rods undergo a conversion process that makes their nuclear material usable as nuclear fuel once again. Not all nuclear reactors are designed to allow this recovery and conversion process. Those that do are called “breeder reactors,” for they “breed,” or produce, additional fuel.
Plutonium is perhaps the most highly toxic substance that exists. The smallest amount can cause such diseases as lung cancer. Workers who handle plutonium observe the strictest safeguards to avoid exposure.
Uranium: From the ground to the reactor
Although uranium can be found in seawater, it is found most commonly in rocks and is as common as the elements tin and gold. It exists in concentrations of about two to four parts per million. Uranium is mined in at least two ways. One is to dig up the ore that contains it, crush the ore, and then treat it with acid, which dissolves the uranium to remove it from the ore. The other is a process called in situ leaching (in situ is Latin for “in place”). In this process, the uranium is dissolved from rock and pumped to the surface of the earth. Either way, the end result is a compound called uranium oxide, or U3O8. This material is often referred to as “yellowcake.”
The uranium, though, cannot be used as fuel in this form. The uranium found in uranium ore consists of approximately 99.3 percent 238U and about 0.7 percent 235U. The concentration of 235U (which is fissile, while 238U is not) has to be increased, or “enriched.” To achieve the desired enrichment, mine operators sell the yellowcake to uranium enrichment plants.
The first step in converting yellowcake into a usable fuel is to convert it into a gas, uranium hexafluoride, or UF6. This gas is then subjected to some process (often a centrifuge) that tends to sort out molecules of different weights. 238U is heavier than 235U, and this fact is exploited in the separation system to achieve a nuclear material with a higher concentration of 235U. The enrichment process increases the amount of 235U from its natural concentration of 0.7 percent, to 3.5 to 5 percent. The uranium is then said to be “enriched.”
The next step is to convert the uranium hexafluoride to uranium dioxide, or UO2. Uranium dioxide can then be processed into pellets that are about the size of a knuckle on a person’s finger. The pellets are then inserted into thin, 12-foot-long (3.5-meter-long) metal tubes, called fuel rods. Bundles of these tubes are then inserted underwater into the core of the nuclear reactor.
Inside the reactor
Imagine that a nuclear power plant has been constructed at a cost of many billions of dollars. (In 2011, the construction cost of a large nuclear power plant in Jaitapur, India, was projected to be around $10 billion.) Construction of our hypothetical plant took at least four years, possibly up to 10 years. Geologists have carefully considered the site of the plant to make sure that the chances of it being damaged by an earthquake or volcanic activity are small. Engineers and construction workers have carefully built the plant. The materials used were of the highest standards. Every weld in metal components was closely examined and even x-rayed to be sure it is as close to perfect as possible.
In this hypothetical plant, provisions were made to ensure that the plant is secure, so that terrorists or others cannot enter and take it over. Provisions have also been made for the safety of the plant’s employees so they can quickly shield themselves from radiation in the event of an accident. The plant is built with “redundant,” or repetitive, safety systems, so that if something breaks down, there is a backup. The most critical of these systems is water that can be used to cool an overheated reactor. Ideally, no detail has been overlooked.
As the time approaches for the plant to come online and begin producing power, the fuel is inserted into the tubes. Then the tubes, up to 200 of them, are inserted into the reactor core. After the tubes have been successfully put in place, the control rods are slowly pulled out. These rods are generally made of graphite or boron, and they control the pace of the nuclear reaction by absorbing neutrons. The farther the rods are inserted, the more neutrons they absorb, slowing down or stopping the reaction. As they are withdrawn, more and more neutrons make it to their target, and the chain reaction begins.
At this point the plant is nowhere near ready to operate at maximum power output. For weeks, the plant’s engineers will fire up the reactor very slowly. They will check and recheck every component of the plant to make sure that everything is operating properly and safely. After a period of several weeks of testing, the reactor will begin producing power at its normal operating level, and consumers will begin enjoying the benefits of the electricity it produces.
Current and Future Technology
Nuclear power plants come in many different shapes and designs. Many of the first plants to be constructed were huge, enabling them to produce the greatest amount of power possible. Some recent designs are smaller, making them less costly and easier to build.
Despite their many technical and engineering differences, nuclear reactors come in two basic types: pressurized water systems and boiling water systems.
Pressurized water reactor system
One system in common use is called the pressurized water reactor system. It is given this name because it relies on water under pressure to produce the heat needed to create electricity. In such a system, the fuel rods are inserted into a steel pressure tank that contains ordinary water. The water acts as a coolant, but it also moderates the reaction because it can absorb neutrons. Protruding through the lid of the pressure tank are the control rods.
As the control rods are slowly pulled out, the chain reaction begins. The reaction produces heat, which heats the water in the pressure tank. The water is heated to a temperature of 518°F (270°C). The water does not boil, though, because it is under intense pressure.
The heated water is then channeled to a heat exchanger in a closed circuit. The water in the heat exchanger is then heated up, producing steam. The steam drives a turbine generator that is little different in principle from a turbine used in a coal-fired power plant. As the generator turns, it produces electricity. Meanwhile, the steam is condensed, usually by cool water from a lake or river, and returned to the heat exchanger.
Boiling water reactor system
The other major system, the boiling water reactor system, is more efficient than the pressurized water system. One noticeable difference is that with a boiling water system, the control rods protrude from the bottom of the containment chamber. Inside the chamber is the reactor core. The control rods are at the bottom because the water inside the chamber is allowed to boil. The steam created by the boiling water is allowed to rise to the top of the chamber. Pipelines carry the steam directly to the turbines, where its heat causes them to turn to create electricity. The steam then condenses and is channeled back into the containment chamber.
Underneath the reactor is a circular tunnel filled partway with water. This tunnel is a safety mechanism. If any steam or water were to escape from the containment chamber, it would fall into the tunnel, where it could do no immediate harm.
The possibility of nuclear fusion
Nuclear fission refers to the splitting, or breaking apart, of atoms. Fission-based reactors produce long-lived radioactive by-products that are difficult to store, and that can be highly toxic to people and the environment if released. Furthermore, there are concerns that rogue nations or terrorist groups could build and use nuclear weapons by illicitly obtaining nuclear materials like uranium or plutonium.
Instead of the fission process that is used today to produce nuclear power, many people would like to see nuclear fusion take its place, since fusion could theoretically supply great amounts of energy for the world while producing far less dangerous by-products than the fission process. But despite decades of research, by the beginning of the 2010s the large-scale generation of power using nuclear fusion was still restricted to the research and development phase.
Nuclear fusion, as the name suggests, involves the fusing, or joining together, of atoms. The light nuclei of two or more atoms bind together during nuclear fusion to form a single, heavier nucleus. One example is the fusing of hydrogen atoms to form a larger, heavier helium atom. When this happens, energy is released. When a helium atom is formed through fusion, its mass is less than the combined mass of the original hydrogen atoms from which it was formed. The mass that disappears is released as energy.
What appeals to scientists seeking to harness nuclear fusion is that such reactions occur throughout the universe, particularly in stars. Fusion takes place in stars because of the high temperatures and pressures found near the star’s center, or core. The temperature of the sun’s core is calculated to be around 27,000,000°F (15,000,000°C). Some stars have core temperatures that are much higher. The problem encountered by scientists in trying to harness the potential of fusion for energy is that while enormously high temperatures and pressures can be found in the centers of stars, including that of the sun, they do not occur naturally on Earth.
Despite the high temperature thought to be needed for fusion to occur, scientists have tried to reproduce fusion reactions on Earth. The process they formulated was to use two isotopes of hydrogen. These isotopes, called “heavy hydrogen” because they contain either one or two neutrons, are deuterium and tritium. Although a “normal” hydrogen atom consists of a single proton in the nucleus orbited by a single electron, deuterium contains one neutron in the nucleus next to its proton, while tritium has a nucleus of two neutrons and a proton. These hydrogen isotopes fuse at lower temperatures than do the nuclei of “regular” hydrogen atoms, and they are relatively abundant. In the ocean, about one in 6,500 or 7,000 hydrogen atoms are deuterium, and they can be easily extracted. The source of tritium is an element called lithium, which is abundant in Earth’s crust.
Scientists discovered that when a mixture of deuterium and tritium is raised to a high enough temperature, or when the elements are accelerated to a very high speed, one deuterium nucleus fuses with one tritium nucleus. The result is a new element, helium. More importantly, excess energy is given off in the form of a neutron that moves at a very high speed.
Scientists believe that fusion could be the “fuel of the future” because the fuel—deuterium and tritium—contains an enormous amount of energy, called “density” by scientists. It has been estimated that a single thimbleful of heavy hydrogen contains the same amount of energy as 20 tons of coal. An amount that would fill the bed of a pickup truck would provide the same amount of energy as 21,000 rail cars full of coal or 10 million barrels of oil. Further, using such fuel would be extremely safe. The only by-product is helium, and there is no danger of a fusion reaction spinning out of control. If the fuel escapes, the fusion reaction simply stops.
A joint project known as the International Thermonuclear Experimental Reactor (ITER) is to be built and operated as a cooperative venture between the European Union, the United States, Russia, China, Japan, and South Korea. The goal of the ITER project is to demonstrate the first successful nuclear fusion reactor by producing 10 times more power than is fed into the fusion reactor. Specifically, for a 50-megawatt power input into the ITER fusion reactor, 500 megawatts will hopefully be produced.
In 2010, construction of buildings for the ITER project was begun in Cadarache, France. As of late-2011, the first fusion experiments at ITER were scheduled to commence in 2019. The successful completion of the ITER fusion reactor is hoped to be a major step in the development of fusion as a potential large-scale source of electricity that will not contribute to climate change, while also producing very little nuclear waste as compared to current fission technology.
The United States has a major experimental fusion facility located at the Lawrence Livermore National Laboratory in California. The fusion facility there is known as the National Ignition Facility. In 2011, it contained the world’s largest and most powerful laser. The laser is used to heat and compress pellets containing both deuterium and tritium. Like the ITER project, the goal of the National Ignition Facility is to obtain a net energy gain from a fusion process—in other words, to get more energy out of the apparatus than was put in. Unlike the ITER project, however, the National Ignition Facility would not create commercial-scale electrical power. Instead, it is a research facility whose findings are intended to advance the science of fusion power production.
As of late 2011, fusion experiments had failed to produce any power in excess of the power needed to produce the fusion reaction. In other words, there was a net power loss.
Cold Fusion
For many scientists, the enormous energy demands of hot fusion make it impractical. Instead, some scientists have searched for a way to create fusion reactions at low temperatures, called “cold fusion.” The term cold fusion was coined in 1986 by Dr. Paul Palmer of Brigham Young University in Utah. It is the popular term for what scientists call “low energy nuclear reactions” in a field that is sometimes called “condensed matter nuclear science.”
In 1984 two scientists, Stanley Pons of the University of Utah and Martin Fleischmann from Britain’s University of Southampton, began conducting cold fusion experiments at the University of Utah. On March 23, 1989, Pons and Fleischmann made an announcement that startled the world. The two claimed that they had successfully carried out a cold fusion experiment. This experiment supposedly produced excess heat that could be explained only by a fusion reaction, not by chemical processes. Many scientists, though, disputed their claim. They tried to duplicate the Pons-Fleischmann experiment and failed.
So the question remains: Is cold fusion possible? Some scientists answer with a no. Many other scientists, though, disagree. They point out that cold fusion research is still ongoing. Some of the problems reported with duplicating the Pons-Fleischmann findings have been the result of normal uncertainties about how to design and conduct experiments to get consistent results.
Meanwhile, many scientists have made claims that they have produced cold fusion. Some of the most prominent researchers in the field are in Japan, where the level of funding for cold fusion research has been much higher than it is in the United States. As of 2012, though, no commercial fusion reactor, whether based on the hot or cold fusion concepts, had been constructed, nor did a successful fusion reactor seem likely to be built anytime in the immediate future.
Benefits and Drawbacks
In the imaginations of many people, nuclear power plants are surrounded by a field of radiation. As they drive down the highway and see the characteristic cooling tower of a nuclear power plant rising on the horizon, some people feel a slight twinge of anxiety. They know that they are not being exposed to radiation, yet their emotions make them wonder if maybe they really are.
Supporters of nuclear energy dismiss these concerns. They argue that nuclear power plants are fundamentally safe and that nuclear power offers many significant benefits. At the same time, nuclear power has significant drawbacks, particularly the potential for accidents, the problem of nuclear waste disposal, and the possibility that terrorists could attack nuclear power plants.
Benefits
The benefits of nuclear energy include the following:
First, many scientists believe that nuclear energy remains the best way to provide large amounts of power for a large and growing world population. A typical nuclear power plant produces 1,000 megawatts, or 1 billion watts, of electrical power. To produce as much power as a nuclear power plant, most other forms of alternative energy require much more land.
For instance, in 2011 the world’s largest wind farm (in terms of power output) was the Roscoe Wind Farm located near Roscoe, Texas. Its rated power capacity is 781.5 megawatts, which is more-or-less the same electrical power output as an average nuclear plant. But the Roscoe Wind Farm uses 627 massive wind turbines and covers nearly 100,000 acres, whereas a nuclear power plant takes up only a tiny fraction of that amount of land—perhaps 500 to 1,000 acres (200 to 400 hectares). Moreover, because of changing wind conditions, the wind turbines do not always operate at peak capacity. To provide the power equivalent to that of nuclear power plants, immense numbers of large wind farms would have to be built.
Second, nuclear energy is reliable. In contrast to most other forms of alternative energy, nuclear energy can be provided on a consistent, predictable basis nearly anywhere in the world. It is not subject to weather conditions. In contrast, solar power requires consistent sunshine, so not all areas are suitable for solar power. Wind power has similar limitations. Hydroelectric dams provide large amounts of power worldwide, but the number of rivers that remain suitable for damming is limited. Such alternatives as ocean wave power and tidal power are likewise limited by geography and unpredictable weather patterns.
Third, the supply of fuel for nuclear power is abundant. Uranium exists throughout Earth’s crust, although in some places, it can be mined more easily than in others. Scientists estimate that the amount of uranium known to be readily available is enough to last 50 years. However, they also point out that its relative abundance has not made it necessary for mining companies to search very hard for it. Scientists are confident that more intensive searching will yield abundant new reserves of uranium. Although uranium is not renewable, as wind and solar power are, enough probably exists for many centuries to come. Further, nuclear plants produce plutonium as a by-product of the nuclear reaction. This plutonium can be reprocessed into fuel.
Fourth, the price of nuclear fuel remains relatively constant, and its sources remain relatively consistent. Uranium is mined extensively in about 20 countries throughout the world. The relatively large number of suppliers ensures that prices do not change rapidly and unexpectedly.
In contrast, the world’s petroleum reserves are in the hands of a small number of countries. Many of these countries are politically unstable. As the Arab oil embargoes of the 1970s showed, oil supplies to the United States and other countries can be cut off overnight for political reasons. Uranium is not subject to these uncertainties, and nations such as the United States and Canada can mine their own uranium. In fact, Canada leads the world in uranium mining. Another leading producer is Australia, which, ironically, had no nuclear power plants in 2011.
Fifth, nuclear power plants have a low impact on the environment in terms of emissions. A chief advantage of nuclear power is that it does not require the burning of fossil fuels such as coal. Thus, it is cleaner than fossil fuels and does not contribute much to greenhouse gas pollution.
Sixth, nuclear power plants are relatively safe. As of late 2011, the only deaths that have resulted from a major nuclear power plant accident occurred at the Chernobyl plant in Ukraine and at the Fukushima 1 plant in Japan. Nuclear experts, though, note that the design of the Chernobyl plant was extremely outdated and that the plant was not very well constructed. This was a common problem for all types of construction under the Communist regime of the old Soviet Union. They believe that the kind of accident that happened at Chernobyl is much less likely with more modern and better built plants.
Regarding the nuclear disaster at the Fukushima 1 nuclear power complex in 2011, the dual events of an unusually large earthquake followed by a tsunami were necessary components to the ensuing nuclear failure. In response to the 2011 Fukushima disaster, officials around the world began taking measures to prevent disasters at nuclear power plants that could be subjected to similar natural cataclysms. Despite worries among the public, some politicians have increasingly seen modern nuclear reactors as a source of energy that can provide reliable power for their countries, while avoiding the emission of harmful greenhouse gases.
Seventh, although a major concern for nuclear plant workers is exposure to radiation, people in general are exposed to radiation every day of their lives. Radiation reaches Earth from the sun, and it radiates from rocks in the earth. This radiation is referred to as “background radiation,” and it varies with altitude (height above sea level) and geography. People living in countries at high latitudes, such as Finland, are exposed to three times as much background radiation as people living in countries at low latitudes, such as Australia.
Drawbacks
Despite its many benefits, nuclear power has significant drawbacks as well. Many scientists, environmentalists, and the public have focused more of their attention on these drawbacks. As a result, nuclear power has become an emotional political issue. Its opponents are passionate in their belief that nuclear power poses a significant danger to the world. Some of their concerns include the following.
Catastrophic accident
The potential for a catastrophic accident continues to exist. By the summer of 2011, the world’s nuclear power plants had accumulated around 14,500 reactor-years of operation. A “reactor-year” represents the continuous operation of a nuclear reactor for one full year. For instance, if 8 reactors operate continuously for 10 years, their cumulative operation represents 80 reactor-years (8 reactors times 10 years of operation). But if the same 8 reactors only operated continuously for 6 months (one-half year), then that level of service would represent 4 reactor-years (8 reactors times 0.5 years).
During those 14,500 reactor-years of operation, there were only three significant accidents: Three Mile Island in 1979 (although the public was not exposed to radiation during that accident), Chernobyl in 1986, and Fukushima in 2011. Supporters of nuclear power point out that far more people lose their lives in accidents at conventional power plants in one year than have lost their lives in nuclear accidents.
The problem is one of public attitudes rather than statistics. Opponents of nuclear power note that a catastrophic accident at a conventional power plant might be tragic for those injured and killed. Still, the effects would be limited to the plant itself and perhaps the immediately surrounding area. Deadly radiation would not be released into the atmosphere. People would not have to be evacuated, and those nearby when the accident occurred would not suffer the ill effects of radiation.
In contrast, a catastrophic accident at a nuclear plant can have enormous effects on the surrounding environment, effects that can last for decades, if not longer. Nuclear opponents believe that the risk is simply too great. One mistake, one faulty component, one operator error could create an environmental catastrophe. The margin for error is nearly zero. Although the risk of a nuclear catastrophe is low, such a catastrophe would have dire consequences, as was seen in the aftermath of the 1986 Chernobyl and 2011 Fukushima nuclear disasters. Taken together, those two disasters have displaced hundreds of thousands of people from their homes. Moreover, the Chernobyl disaster led to a significant increase in thyroid cancer among young people living within the regions most affected by Chernobyl’s radioactive fallout.
Adding to the problem is the mysteriousness of anything nuclear. Ever since the atomic bombings of Japan at the end of World War II, many people have feared nuclear power. Excessive exposure to nuclear radiation can cause cancer, another word people respond to with fear. Few people understand nuclear physics. That sense of awe and mystery spills over into fear of anything “nuclear,” including nuclear power plants.
Waste storage and disposal
Nuclear waste comes in two types: low-level and high-level. Low-level waste is produced by hospitals, which use radioactive materials for certain medical tests. Similar low-level waste is also used for research purposes at universities and other research facilities. This material has to be disposed of safely, and if it is done so, it poses little health risk to the public. The radioactivity in these materials breaks down quickly (usually in days or at most weeks), and the material can then be disposed of as normal trash.
High-level nuclear waste, such as that produced by nuclear power plants and in producing and dismantling nuclear weapons, is another matter. As of 2011, the United States had accumulated around 72,000 tons of spent nuclear fuel rods. These are fuel rods that have been removed from power plants because the fuel is depleted. This amount would cover a football field to a height of nearly 15 feet (about 5 meters). Much of this material is stored in water pools on the sites of nuclear power plants. According to the U.S. Nuclear Regulatory Commission (NRC), about 2,000 tons of spent fuel rods are being added to the nation’s inventory each year. The NRC predicted in 2011 that unless a more permanent storage solution is found, U.S. nuclear plants may run out of space to store their spent fuel rods by 2015.
The problem with nuclear waste is the half-life of such elements as uranium and plutonium, as well as other radioactive materials produced in nuclear power reactors as by-products. Some of these by-products include cesium-137 and strontium-90, both highly radioactive. Most of these elements have extremely long half-lives. The half-life of plutonium is 24,000 years. The half-lives of some other radioactive elements are 100,000 years, even longer. This means that nuclear waste disposal has to be considered in terms of geologic time, not next year or even the next century. The ancient Roman Empire was thriving just 2,000 years ago; the ancient Egyptians, 3,000 years ago. Humans find it hard to think that far ahead.
Roughly every 12 to 18 months, a nuclear plant has to shut down and all the fuel rods have to be replaced. These fuel rods are highly radioactive, so they cannot simply be taken to the nearest landfill. Strict precautions must be taken to make sure that the spent rods do not pose a risk to the environment or to the public. Further, when a nuclear plant is “decommissioned,” or shut down, the radioactive components in the core have to be disposed of properly. All of this is a difficult technical undertaking and one that carries a high expense.
Several proposals have been made for ways to dispose of high-level nuclear waste. One proposal is to launch it into space. Others ideas include burying it on a remote island or in the polar ice sheets. So far, these ideas have not been attempted. Another proposal is to bury the waste under the seabeds. Although this is technically possible, the expense of doing so would be enormous.
The most widely accepted possibility is to bury nuclear waste underground in stable geological formations. The waste would first undergo a process called vitrification (from the Latin word vitrium, meaning “glass”). This means that the waste is mixed with silica (like sand) and melted into glass beads. This process makes the waste more stable and reduces the chance that radiation could seep out into the air or water. The beads are then buried in an area that is geologically stable (that is, it does not experience earthquakes, tremors, or volcanic activity). When the storage facility is full, it would be sealed with rock.
The problem with this method is that no community wants to be home to the storage site. Nuclear waste would have to be trucked in, with the potential for accidents. Then the nuclear waste would be stored nearby, essentially forever.
In 1983 U.S. President Ronald Reagan signed into law the Nuclear Waste Disposal Act. Under the act, the federal government took on responsibility for nuclear waste disposal. The act required the U.S. Department of Energy to find a suitable site for underground storage, then build the facility. In 2002 the department identified Yucca Mountain in Nevada as the most suitable site.
Understandably, Nevadans do not want to be the dumping ground for the nation’s nuclear industry and have opposed this plan. The state’s governor notified the federal government that Nevada was against the plan. The U.S. Congress voted to override the governor’s objections. Accordingly, the federal government under the George W. Bush administration (which ran from January 2001 to January 2009) designated the Yucca Mountain site as a long-term storage facility for about 70,000 metric tons of nuclear waste.
When Barack Obama became president in 2009, his administration’s view of the Yucca Mountain waste site differed from that of the preceding Bush administration. In 2010, the U.S. Department of Energy notified the Nuclear Regulatory Commission of its intention to terminate its application to license the Yucca Mountain site as a long-term storage facility for high-level nuclear waste. President Obama instead ordered Dr. Steven Chu, the energy secretary, to assemble a commission to find an alternative long-term solution for storage of the nation’s high-level nuclear waste.
Another problem the nuclear industry has created is “mill tailings.” These are waste materials created in mining uranium ore. The materials contain trace amounts of uranium left behind, as well as radium and thorium, both radioactive. The radioactive material cannot simply be left in place. The federal government, specifically the U.S. Nuclear Regulatory Commission, regulates the removal, storage, and monitoring of mill tailings.
Terrorism
After the terrorist attacks on the United States on September 11, 2001, policymakers raised concerns about the security of the nation’s nuclear power plants. It is known that members of al-Qaeda, the Islamic fundamentalist terrorist network, have been instructed and trained in ways to attack power plants. The concerns of policymakers and nuclear regulatory officials are many:
- As they did on September 11, 2001, terrorists could hijack an airliner and fly it into a building, but in this scenario a nuclear power plant would be targeted. According to the Nuclear Control Institute’s Web site (http://www.nci.org/), the NCI scientific director believes that a direct, high-speed impact by a large airliner “would in fact have a high likelihood of penetrating a containment building” with a nuclear reactor inside. “Following such an assault,” he said, “the possibility of an unmitigated [unstopped] loss-of-coolant accident and significant release of radiation into the environment is a very real one.” Other scientists believe that most nuclear plants could withstand the impact of an airliner.
- Terrorists could steal plutonium or highly enriched uranium, either from the nuclear plants themselves or from uranium enrichment facilities. It takes only about 18 pounds (8 kilograms) of plutonium or 55 pounds (25 kilograms) of highly enriched uranium to build a nuclear weapon. But in the nuclear industry, these materials are moved about by the ton, and accurate records are not always kept. Policymakers believe that a sophisticated terrorist group could steal these materials and make a nuclear bomb. The materials could also be used to construct so-called “dirty bombs,” or what experts call “radiation dispersal devices.” These are bombs made of conventional explosives such as dynamite that are packed with nuclear materials, even nuclear waste. The explosion would disperse, or distribute, the radioactive materials around a wide area. The result would be public panic and an area contaminated with radiation.
- Policymakers are also concerned about security at nuclear facilities. After the 9/11 attacks, training exercises were carried out at nuclear plants to see how well the plants’ personnel could resist a terrorist attack. Military personnel disguised as terrorists attempted to gain access to these plants. Some experts claim that at nearly one-half of U.S. nuclear power plants, armed guards were not able to stop these mock attacks.
A final concern is nuclear proliferation. Proliferation means “spreading,” and the concern is that nations can develop nuclear power—or claim to—and convert their nuclear capabilities into weapons. Throughout the 2000s and continuing into the 2010s, many nations of the world, including the United States, were opposing nuclear development programs in Iran and Communist North Korea. North Korea announced in 2006 that it had conducted its first-ever test of a nuclear bomb. Another North Korean test reportedly occurred in 2009. Hence, after years of official denial, the military use of nuclear material was publicly acknowledged by the North Korean government.
By contrast, as of early 2012, the government of Iran continued to insist that its development of nuclear technology was strictly for peaceful purposes, such as power plants. Although Iran’s government has insisted that its nuclear program exists for peaceful purposes, other nations have worried that Iran was trying to develop nuclear weapons.
Environmental Impact
The chief benefit to the environment of nuclear power plants is that they do not emit harmful gases, such as carbon dioxide and sulfur dioxide (unless, of course, an accident occurs). In this way they differ from conventional power plants, which emit these gases primarily because they burn coal, a fossil fuel. If the energy generated by nuclear power plants worldwide were instead generated by burning coal, the amount of additional carbon dioxide released into the atmosphere would be about 1,600 million tons.
Moreover, burning coal releases toxic heavy metals, including arsenic, cadmium, lead, and mercury. Nuclear energy prevents release into the atmosphere of about 90,000 tons of these metals each year. France’s heavy reliance on nuclear power has lowered that country’s air pollution from electrical generation by 80 to 90 percent.
By not emitting these greenhouse gases, nuclear energy does not contribute to environmental problems such as air pollution, smog, and the “greenhouse effect.” The greenhouse effect refers to the ability of some gases, such as carbon dioxide, to accumulate in the air. The theory is that in doing so, they act like a greenhouse, trapping the sun’s heat. In turn, many scientists believe that this trapped heat is increasing average temperatures around the world. This increase is referred to as “global warming.” The vast majority of climate scientists agree that global warming is occurring, and that its effects include rising sea levels; melting of the Arctic polar ice, as well as glaciers throughout the world; and disruption to the habitats of animals and people in some regions of the world due to the overall increase in temperatures.
The lack of polluting emissions from nuclear power plants also means that they do not contribute to acid rain. Acid rain is any form of precipitation that is more acidic than normal because the water has absorbed acidic pollutants from the air. Acid rain can harm crops and forests. It can also contribute to the deterioration of buildings and public monuments, which dissolve because of the acid in precipitation.
Nuclear power plants also do not harm surrounding bodies of water. Some people believe that nuclear plants discharge water into nearby lakes and streams that is either radioactive or extremely hot. This is not true. The water released from a nuclear plant never comes into contact with the radiation. Further, if the water is too hot to be discharged, it is cooled either in a cooling pond or in cooling towers before release.
Supporters of nuclear power point out that some other alternative forms of energy do not have the same low impact on the environment, especially hydroelectric dams. Although such dams have the benefit of not emitting harmful gases or pollutants, the dams have a major impact on the surrounding environment. By turning rivers into huge lakes, they disrupt vegetation and wildlife. Many dams have displaced (driven out) large numbers of people.
Further, the reservoirs behind hydroelectric dams emit their own form of pollution. As the water level of the reservoir falls, the wet ground that surrounds it supports the growth of vegetation. As the water rises, this vegetation is covered and rots. The rotting vegetation emits methane gas, a powerful greenhouse gas pollutant that is much more potent than carbon dioxide. In addition, hydroelectric dams have an adverse effect on fish because they disrupt breeding and spawning grounds.
Nuclear power plants do not have harmful effects on wildlife (except in the case of a major accident, such as the ones at Chernobyl or Fukushima). In fact, nuclear power plants often can have beneficial effects. For example, when cooled water is released from the plant, the water often contributes to the formation of wetlands. These wetlands can become nesting grounds and provide habitat for birds, fish, and other animals. Some companies that build and run nuclear plants even develop wildlife preserves and parks in the surrounding area, where plants grow abundantly in the moist soil.
Even species that are endangered (that is, in danger of becoming extinct) have found new life around nuclear plants. Some of these species thrive nearby, including such endangered species as bald eagles, red-cockaded woodpeckers, peregrine falcons, osprey, and the beach tiger beetle. he areas around nuclear plants are also home to such nonendangered species as wild turkeys, sea lions, bluebirds, kestrels, wood ducks, and pheasant.
Again, supporters of nuclear power point out that other forms of alternative energy do not have the same benefits. They agree that solar power and wind power are cleaner forms of energy, but they require huge “farms” of solar panels or wind turbines to produce significant amounts of electricity. Some argue that wind farms hurt an area’s bird populations because the birds become almost hypnotized by the turning blades and fly right into them, where they are killed. By reducing an area’s bird populations, the rodents that some birds eat can multiply freely and cause rodent infestations.
Nuclear power protects land and animal habitats. Per unit of electricity, nuclear power plants take up far less land than other types of power-generating stations. For example, consider a nuclear plant that produces 1,000 megawatts of power (a megawatt is 1 million watts, so 1,000 megawatts is 1 billion watts). To produce the same amount of power, a solar farm would need 35,000 acres of solar panels. A wind farm would require 135,000 acres devoted to wind turbines (however, since large wind turbines must be spaced quite a distance apart from one another, only a small number of the 135,000 acres would actually have windmills placed on them). In contrast to solar and wind farms, a typical nuclear power plant takes up a total of only about 500 acres of land.
Further, the fuel that nuclear power plants use, uranium, is very energy dense. This means that a pound of the fuel produces far more energy than a pound of coal. For example, 1 metric ton of uranium, or about 2,200 pounds (1,000 kilograms), will power a 1,000-megawatt nuclear power plant for two weeks. This fuel would come from about 9 metric tons of mined uranium oxide. The same amount of energy from coal would require about 160,000 metric tons, or almost 353 million pounds. Thus, mining nuclear fuel has much less impact on the environment.
With regard to energy output, some nuclear power opponents say that these figures are misleading. They point out that conventional fuels like coal have to be burned to process uranium for use as fuel. They are correct, but the amount of conventional energy that has to be burned to do so is only about 2 percent of the amount of energy the uranium will produce.
Economic Impact
In examining the cost of nuclear energy, many factors have to be taken into account. Some of these are obvious, such as construction costs and the cost of mining uranium. Others are more hidden and include taxes, licensing fees, interest payments on debt, and the like. There is also the expense associated with storing the nuclear waste from a power plant. And though they are rare events, nuclear disasters like the ones at Chernobyl in 1986 or at Fukushima in 2011 can cost many tens or hundreds of billions of dollars in property damage, medical costs, long-term deactivation and monitoring of the defunct reactor(s), and so on. Thus, any examination of the economic costs and benefits of nuclear energy involves complex calculations.
The first cost comparison involves the fuel itself. Uranium has to be mined, converted, enriched, and loaded into fuel rods. Coal has to be mined, but it can be used as is. However, the cost of transporting nuclear fuel is low because of its energy density. The cost of transporting coal is high because large volumes have to be shipped.
Per unit of energy, the cost of a nuclear power plant is generally higher than that of a conventional power plant. Nuclear power plants have to be built to the highest standards. Many of their systems are redundant, or repetitive, for safety reasons. In contrast, coal-fired plants have additional costs because of requirements that they have pollution-control devices, such as scrubbers that remove particles from their emissions. Debt also increases the cost of nuclear plants. Because building these plants is so expensive, power companies have to borrow large sums of money, and they have to pay interest on that debt. Thus, high interest payments have added to their costs.
Nuclear power plants have higher maintenance costs than do conventional power plants. For example, corrosion and cracking are common problems in the water pipes in boiling water reactors. These components have to be replaced at great cost. In the meantime, the reactor is shut down. It is not producing energy, but workers still have to be paid and debt still has to be financed.
Both conventional and nuclear power plants have normal day-to-day costs. Nuclear facilities require highly trained technicians, engineers, safety inspectors, health workers, and the like, increasing labor costs. Conventional plants are relatively simple to operate, so they do not require as many highly trained workers. However, they require a larger labor force because of the amount of labor involved in running the plant’s operations.
Nuclear plants face other charges as well. The Nuclear Regulatory Commission charges fees for operating active nuclear reactors in the United States. In 2010, the license fee was nearly $5 million. Besides license fees, many nuclear plants pay $15 to $20 million in local property taxes. In addition, the Nuclear Regulatory Commission requires nuclear plant operators to take on expenses for other specialized needs, including, for example, radiographers who measure radiation in the plant. Producing nuclear energy does not come cheap.
On top of all these expenses, the nuclear industry spends many dollars for nuclear waste storage and disposal. Coal-fired plants have only to dispose of ash. Further, the cost of decommissioning a nuclear power plant is high, often 4 percent of the initial cost of construction. A coal-fired plant that is put out of commission essentially just has to be knocked down and carted away. Yet most costs are comparable. The end result is that nuclear power is slightly more expensive than coal.
Societal Impact
The societal impact of nuclear power tends to be a matter more of perceptions and public sentiment than facts. Opinions about nuclear power are likely to depend on opinions about science. Many people place a great deal of faith in science. They believe that science can solve many of the world’s ills. Science, for example, can increase crop yields in poorer nations. It can reduce and eventually eliminate many diseases. And it can provide for the energy needs of the billions of people who live on Earth—a number that reached 7 billion in 2011 and is expected to exceed 9 billion by 2050. Scientists, with their specialized knowledge, have become almost like magicians who solve the world’s problems.
As the sheer volume of scientific information grows each year, however, the public feels disconnected from scientists and their “magic.” Few people know in detail how a toaster works, or especially something as complex as a nuclear power plant. Further, they believe that while science can solve problems, it has also caused problems. In their view, Earth and its resources have been exploited in the name of science. The atmosphere and bodies of water have been polluted because of scientific and technological advancement. Some of the people who feel this way yearn for a simpler time, when people (in their view) lived in harmony with the natural world. They were attuned to the cycles of the natural world and accepted them rather than trying to conquer them through science.
Nuclear energy stands at the center of this dilemma. Supporters of nuclear energy point to its clear benefits. It provides large amounts of power. It does not release pollution into the atmosphere. It does not consume resources whose supply will eventually run out. It does not make countries such as the United States dependent on foreign sources of fuel. It has an exemplary safety record, and improvements in the design of nuclear power plants make them safer than ever. Perhaps most importantly, nuclear power is the best hope for developing nations such as India and China. These and other countries are attempting to find a place for their large populations among the developed nations of the world. To do so, they need energy.
In the early 2010s, both India and China were forging ahead with plans to dramatically increase the number of nuclear power plants in their respective countries. In the case of India, more than half (56 percent) of the rural Indian households in 2011 had no access to electrical power. The rural households lacking electricity represented 400 million people. India’s government planned on a big increase in nuclear power to bring electricity to its rural areas. Although only 3 percent of electrical power came from nuclear plants in 2011, the government projected that by 2050, nuclear power will generate 25 percent of India’s electricity.
The idea that nuclear power should be expanded greatly is not shared by all people. Many environmentalists believe that nuclear power plants are a disaster waiting to happen. Their views are sometimes supported by the mass media, which often focuses more on negative stories than on positive pieces. A documentary prepared by the Public Broadcasting Service (PBS) is a case in point. The documentary was titled “Meltdown at Three Mile Island.” Although this title is dramatic, it is false. No “meltdown” occurred at Three Mile Island.
Barriers to Implementation or Acceptance
Popular culture adds to the climate of distrust and emotional debate surrounding nuclear energy. Movies routinely depict scientists as “mad,” as people bent on making scientific discoveries no matter what effects those discoveries might have on the human community. Cable-TV’s science fiction channels routinely run movies about creatures that have mutated into killer beasts because of science, especially nuclear science. One of the best examples of these killer beasts is Godzilla. In many instances, the best stereotype of a scientist is one of an unappealing, slightly eccentric person. In this climate, the mysteries of nuclear power become an easy target for people’s fears and uncertainties about the future.
During the first decade of the 21st century, nuclear energy development was largely on hold, particularly in Western nations such as those in North America and Europe, as well as Australia. The Fukushima disaster in Japan in 2011 only deepened the reluctance of the public and of policymakers to increase the use of nuclear power in those countries.
Nevertheless, in 2011 several European countries were constructing new reactors. Russia was building eight large nuclear reactors. Finland and France were each adding one large reactor, and the little nation of Slovakia was building two new reactors. Several other European countries were in the planning stages to add new nuclear power plants. But in contrast to the new construction taking place in several neighboring countries, Germany announced in the aftermath of the 2011 Fukushima disaster that it would close down all of its nuclear power plants by 2022. However, in 2012, the United States announced plans for two new nuclear reactors, the first approval there in 30 years.
Many other countries, first among them the United States, looked to increase nuclear power production by increasing the rated power capacity of its existing nuclear reactors. Increasing the capacity of existing nuclear reactors avoids much of the resistance that would be encountered by attempting to construct an entirely new nuclear power plant where one has not been constructed previously.
Generally speaking, public sentiment in the West favors alternatives to nuclear energy, such as solar, wind, and water power. This sentiment was greatly strengthened by the 2011 Fukushima disaster. Less developed nations, though, do not have the luxury of picking and choosing like the richer and more technologically advanced nations. So, many developing nations are going ahead with plans for nuclear power plants. Foremost among those developing nations is China, which had 27 new nuclear reactors under construction by early 2011.
At the same time, India was building four new nuclear reactors. There were protests in India, however, as local residents expressed their misgivings about new nuclear power plants being built near their homes, especially in light of the widespread radioactive contamination that occurred in Japan in 2011. But despite the Fukushima disaster and the resulting negative influence it had on public attitudes, the governments of China, India, as well as those of a number of other Asian countries, were going ahead with plans in the early 2010s to greatly increase their use of nuclear power.