Nuclear Energy – Understanding the Basics
Nuclear energy is scary for many of us, because we really don’t know how it works. Depending on our generation, we might have preconceived ideas shaped by pop-culture bias and media distortion. Or maybe we just know that accidents have happened in the past, and must be possible in the future. We re-live the horrific images from the 2011 earthquake and tsunami in Japan, and question the safety and damage control measures at the Fukushima nuclear plant. We remember the Chernobyl Disaster and the Three Mile Island incident, and wonder about the final fallout of those events. Indeed, like other sources of electric power generation around the world, nuclear energy has inherent risks that should be understood and addressed.
However, in order to de-mystify nuclear energy, it’s important to have a basic understanding of nuclear technology, the nuclear process, and the nuclear fuel cycle. If we understand the basics of nuclear energy, we have a foundation to discuss nuclear safety, nuclear radiation, and nuclear waste.
Nuclear Energy – Comparison with other Forms of Energy
Energy is generated from natural resources such as gas, oil, coal, water, wind, solar, and uranium. Electrical generation plants use the heat or motion of these resources to generate electricity. Most power plants produce electricity by boiling water to produce steam. The steam is used to spin a turbine. The shaft of the turbine spins a large coil of wire between two magnets. The spinning coil of wire generates electricity. That’s why they call it a “generator.”
The main difference between a nuclear power plant and other kinds of power plants is the way the water is heated to steam. In a gas-, oil-, or coal-fired plant, heat is produced by the burning of gas, oil, or coal. In a nuclear power plant, heat is produced by splitting uranium atoms.
In a nutshell, nuclear energy is a very sophisticated and efficient way to boil water and spin a turbine. In fact, nuclear energy currently generates about 20% of the electricity in the U.S. and 16% of the total electricity in the world.
Nuclear Energy -- Nuclear Fission and the Nuclear Reactor
When a uranium atom absorbs a neutron and splits, this produces heat energy in a process known as ‘fission.’ In fission, two or more neutrons are released from the nucleus of the uranium atom and these neutrons are then free to bounce around and hit other uranium atoms, causing them to split. This process repeats itself in a controlled chain reaction.
Control rods are used to control the speed of the chain reaction, by sliding up and down the fuel assemblies in the reactor core. The control rods contain certain chemicals, which have atomic structures that absorb neutrons. Basically, the control rods act like neutron sponges. If the rods are lifted out of the core, fewer neutrons are absorbed and more neutrons are available for fission, which generates more heat energy. If the rods are lowered into the core, more neutrons are sponged-up, which slows the chain reaction and decreases heat energy output.
The temperature in the reactor core is carefully monitored. If the monitors detect an unacceptable change in temperature, the fission process is automatically stopped by dropping control rods into the core.
Nuclear Energy – The Nuclear Power Plant
The main parts of a nuclear power plant are the reactor core and the containment structure. The reactor core is comprised primarily of uranium fuel assemblies and control rods. The reactor also needs a coolant and moderator to complete the basic system. At most nuclear power plants the coolant is simply water. The coolant not only keeps the core from getting too hot, but also converts the reactor's heat to steam, which is needed to generate actual electricity from the nuclear fission process.
Basically, the cooling system removes heat from the reactor core and transports it to another area of the plant, where the thermal energy can be harnessed to produce electricity. Typically, the hot coolant will be used as a heat source for a boiler, and the pressurized steam from the boiler will power several turbines that drive the electric generators. The water is also a moderator that slows down the speed of the neutrons, which allows the uranium atoms to “catch” enough neutrons to keep the chain reaction going.
The final part of the nuclear reactor is the pressure vessel, which surrounds and protects the components in the reactor core. The pressure vessel, made of 9-inch thick steel and often weighing more than 300 tons, provides one more important safety barrier at a nuclear power plant.
Nuclear Energy – What is Uranium, Really?
Uranium is the fuel of the nuclear power plant. Not known to many, uranium is a naturally-occurring chemical element that is mined from the earth just like gold and silver. In fact, natural uranium is much more plentiful than gold and silver.
The world’s known uranium resources are relatively plentiful and readily accessible. There are also many locations where the uranium reserves are untapped. Even without new exploration and extraction technologies, the world has a few hundred years of available supply. Of course, this does not take into account the effect of increased recycling of the nuclear fuel used in the reactor. Also, there’s thorium, another naturally-occurring metal in the earth, which is four times more plentiful than uranium. While thorium has traditionally been considered a waste product at rare earth mining sites throughout the world, it’s now been successfully processed into a viable fuel source for nuclear reactors.
A single uranium pellet about the size of a standard pencil eraser contains as much energy as 17,000 cubic feet of natural gas, 1,780 pounds of coal, or 149 gallons of oil. Think of the energy produced by one train car of coal vs. one train car of nuclear fuel assemblies. Indeed, pound-for-pound, uranium is super efficient.
Nuclear Energy – Nuclear Possibilities
Even as the world seeks to conserve energy and natural resources wherever it can, the reality is that the world’s economic growth and quality of life depends on a minimum load of power every minute of every day. “Baseload electricity” is the continuous, round-the-clock power required to run our world. In the U.S., about 60% of the electricity used to operate our homes, businesses, schools, hospitals, military, communication networks, emergency services, and transportation systems is considered “baseload.” In a nutshell, baseload electricity is a key component to our economic growth, national security, and quality of life.
With the spotlight on fossil fuels and carbon emissions, the world is currently exploring the viability of “new” energy alternatives such as wind, solar, geo-thermal, and bio-fuels. While baseload and renewables can work together in achieving future energy goals, experts from across the ideological spectrum agree that any realistic energy policy must include nuclear.
U.S. demand for electricity is expected to increase by 40% over the next 25 years. However, recent pushes to limit emissions will make it impossible to meet this demand with traditional fossil fuel power plants. Despite the contributions of renewable energy sources like wind and solar, the current reality is that only nuclear power can provide large amounts of emissions-free, baseload electricity.
Nuclear Energy – The Future, Today
The nuclear energy industry in the U.S. currently provides 20% of our energy needs in a safe and reliable network of 104 nuclear reactors. There’s no question that the numbers work, the footprint is available, and the technology is proven. The U.S. public desires energy that is clean, safe, and affordable – and nuclear energy can meet all of these criteria.
Of course, nuclear energy requires a safe and manageable regulatory and inspection structure. However, with these safeguards, the nuclear technology of today can already provide safe and expanded energy production. Unlike some of the other “new energy” solutions, this isn’t a question of research and development or technology and feasibility or scalability and sustainability… It’s simply a matter of doing more of what works, in a safer and more efficient way.