How a nuclear energy plant works isn’t all that different from how a coal plant works. Both technology types heat water, which turns into steam, which provides the power to turn a turbine generator, which produces electricity. According to the website, "How Stuff Works," the difference in the technology is based on the question of how to heat the water.
While most of the earth’s energy is created by burning fossil fuel, in 2009, 14% of the earth’s electricity was produced by approximately 400 nuclear power plants, all of which used fission, or the splitting of the atom, to heat that water to produce that steam to spin those turbines to create the energy to send down the grid to turn on the lights in the house that Jack built.
Although it is possible to use thorium for the production of isotopes for induced atom splitting, the most-used element is uranium.
Uranium-235, an isotope of uranium designated as U-235, deteriorates naturally at a very slow rate by throwing off alpha particles (two neutrons and two protons bound together), producing radiation (alpha radiation) in the process.
Fission can be induced in uranium for nuclear power purposes by enriching a uranium sample so that it has 2 or 3 % more U-235, then by firing a free neutron into the nucleus of a U-235 atom. (Weapons-grade uranium has at least 90% enrichment.) As soon as the atom captures the free neutron, the atom splits into two lighter atoms, and throws off either two or three new neutrons, depending on how it splits. This produces 200 million electron volts per atom. It releases high heat and gamma radiation (high-energy photons). Each of the new atoms that are a result of the split emit beta radiation (fast electrons) and more gamma radiation. This is much hotter and more powerful than alpha radiation. Each pound of enriched uranium used to power a nuclear submarine is the equivalent of approximately one million gallons of gas.
A nuclear power plant controls the energy of this reaction and uses it to heat water into steam. There are lots of types of nuclear power plants, all of them concerned with controlling this powerful process for the safety of the workers and the public.
Currently, a typical system involves forming enriched uranium into pellets, which are formed into rods, which are collected into bundles. The bundles are submerged into water under pressure. The water cools the rods, preventing melting. Control rods that absorb neutrons are put into the bundle with a system that can control the rate of the nuclear reaction. More heat is produced if the control rods are lifted out of the bundle, less heat if they are lowered into the bundle. The rods are lowered completely into the bundle to shut the plant down for maintenance, fuel changes, or emergencies.
In some plants the steam produced by the heat is channeled into another loop so that the radioactive water never contacts the turbine. In some reactors the coolant fluid is gas or liquid metal, so that the plant can be safely operated at higher temperatures.
Concrete plays an important role in housing the pressure chambers with multiple layers of protection to stop radiation and to prevent leakage of gases, fluids or water. With the tsunami incident in Japan, earthquake analysis will play a large role in future design.
Nuclear policy was designed during the Eisenhower administration to include a full cycle of recycling the “waste” products of “Atoms for Peace.” Near the end of Ford’s presidency, the recycling of nuclear waste was prohibited. The problem of nuclear waste has ballooned into a game of NIMBY, with no one wanting a nuclear waste depository in their backyard. With the public pre-occupied with fear regarding toxicity and thousands of years of half-life, many people are unaware that most nuclear waste can and should, by design, be recycled.
The principal problem with nuclear power is ignorance, not only on the part of the public, but on the part of legislators. Nuclear science is in its infancy. The advances being made today on the frontier of fusion technology will nullify the hysteria, but it is vital that the public and especially the lawmakers educate themselves and each other on the reality of nuclear power. We cannot meet the future needs of the human race with fossil fuels, and those who believe that the alternative energy sources of wind, solar and bio-fuels are more efficient than nuclear power are misinformed.
The future is fusion.
Fusion is a different process from fission. As little as four years ago, fusion research was laughed at as a pipe dream, but there is now serious international efforts to get the necessary infrastructure built within the first half of the 21st Century. The Web site for the Culham Center explains the drive for fusion power.
Gas from deuterium and tritium (types of hydrogen) is heated to 100 million degrees Celsius in a magnet confinement chamber, controlling the gas (called plasma) with magnets. One such chamber is the ‘tokamak,’ a Russian term for a ring-shaped device (torus) that shows the most promise for delivering fusion on a large scale basis.
Instead of splitting the atom, atomic nuclei collide, and release energy in the form of neutrons. The advantages? The website lists six rather impressive advantages:
No carbon emissions; for those of you who believe that CO2 is bad for you, fusion’s by-product is helium, an inert gas.
The source of the hydrogen types are found in lithium, a common substance in the earth’s crust, and water. The fuel will available for millions of years.
One kilogram of fusion fuel is the equivalent of 10 million kilograms of gasoline.
Only structural items in the nuclear plants become radioactive, and they will be ready for conventional disposal within 100 years.
The amounts of fuel used at one time are literally tiny, weighing “less than a postage stamp,” making large-scale accidents virtually impossible.
The power plants will be reliable sources of large amounts of electricity at costs that are similar to present technology.
To good to be true? Not at all. The present level of education regarding nuclear science is too bad to be believed. Not only is nuclear fusion possible, the research and development is up and running. The JET (Joint European Torus) has produced 16 megawatts of fusion power. The roadmap for development will include ITER (an international project to build a 500 megawatt torus to prove that fusion power is feasible on a commercial scale, to be placed in France). In conjunction with ITER will be IFMIF, (International Fusion Materials Irradiation Facility) used to test materials needed in the power station. The resulting DEMO will be a demonstration power plant supplying fusion electricity to the grid, which is expected to start operating in 2019.
The work at Culham Centre in the UK is funded by the Engineering and Physical Sciences Research Council, and by the European Union under the Euratom treaty, as well as other national programs.
The website has frequently asked questions here.
This activity can be accelerated with proper funding. Although it is supported by international agreements, the funding level should be much higher, and expectations to that effect should be communicated to your legislators.