What is nuclear power?
The definition of nuclear power:
Nuclear power is the use of nuclear reactions that release nuclear energy; that is generating heat (boiling water that makes steam), which is used to turn turbines to generate electricity.
Nuclear power is energy contained in atoms. This energy can be released as heat which turns water into steam which turns a turbine which then generates electricity.
How much energy can one atom make?
One atom can make a large amount of energy. Albert Einstein proved this with an equation:
E = mc2
E is the Energy, m is the mass, and c is the speed of light. This equation states that you can turn a tiny amount of mass into a huge amount of energy. This is possible because c is a large number and c squared is even a bigger number. Thus it should be possible to make lots of energy from not very much at all, and this is the basic idea behind nuclear power.
Nuclear plants work by splitting very large atoms into smaller, more tightly bound and more stable atoms. By splitting big atoms into smaller atoms you generate a huge amount of heat, and this generated heat is a form of energy and you can harness this energy.
What is the cost to build a nuclear power plant?
A typical cost to construct and build a nuclear power plant with a generation 3 reactor that gives between 1400 – 1800 MW will be in the region of USD 5 – 6 billion. That amount of money in South African Rand (ZAR) will be R 84 316 800 000.00, this is about R84, 3168 billion.
How long does it take to build a nuclear power plant?
First of all, the nuclear power plants are very complex to construct and build and their construction periods are longer than the other power plants that do not use nuclear power. The estimate time to construct and build a large nuclear power plant will be between 5 to 7 years (This is only the time taken to build the plant and not the planning and licensing).
Other factors that take so long to build the nuclear power plant is that the plant have a lot of resources, the equipment is very expensive, and most important, there must be safety equipment installed (a lot of safety is required). To compare the time that it take to build a nuclear unit, large coal plants can be built in 4 years, and natural gas plants can be built in 3 years.
The use of Uranium fuel rods:
To power the nuclear power plants, you need Uranium ore.
What is Uranium?
Uranium is a very heavy metal with a very high density that can be used as an abundant source of concentrated energy.
But you cannot use the raw Uranium ore in the nuclear power plants; it needs to be processed into a usable fuel.
After mining the ore, it is then crushed and ground up. This grounded ore is then treated with an acid to dissolve the uranium which is then recovered from a solution. The end product of the processed uranium ore will be Uranium oxide concentrate (U3O8).
This concentrate (is mildly radioactive) is not yet a usable fuel and needs to be processed further.
[The image on the left is the Uranium oxide concentrate or known as yellow cake].
This uranium oxide is then converted into gas (uranium hexafluoride (UF6) which enriches the uranium. After the enrichment it is converted into uranium dioxide (UO2) which is formed into fuel pellets.
[Left: Nuclear fuel assembly]
All this fuel pellets are placed inside thin metal tubes that are assembled into bundles to become the fuel elements in the core of the reactor.
The lifetime of the uranium fuel rods is between 3 – 6 years. After these amounts of years, the fuel rods are removed, stored or reprocessed or disposed underground.
Advantages and disadvantages of nuclear power:
• Electricity generation from nuclear stations reduce the energy generated from fossil fuels which means lowering greenhouse emissions.
• Nuclear stations use less fuel that offers more energy.
• The production of the electricity is a continuous process.
Disadvantages of nuclear stations:
• The nuclear waste takes a very long time (actually years) to eliminate radioactivity.
• Nuclear plants have a limited life span.
• Not all the countries have nuclear technology or Uranium ore.
• Strict safety rules and safety precautions.
Is nuclear power good or bad?
Nuclear power can be good and bad. For all the good reasons are that you are using fewer materials to generate a huge amount of electricity and you are lowering the greenhouse emissions. The electricity generating process is a continuous process; this means there are almost no electricity failures.
But if you are using nuclear power, it can also be dangerous, because nuclear power is highly radioactive that can cause extreme damages if not handled with extreme care and safety precautions with strict safety regulations and rules. With one wrong decision or a small mistake in managing the plant, it could destroy a lot of lives and kilometers of land and surface area around the plant would be radioactive. This would make the area around the nuclear station inhabitant for decades of years because of the extreme dosage of radioactivity. Thus the nuclear power can be good in their ways and also very bad if not handled in a properly way.
Nuclear fusion vs nuclear fission:
Nuclear Fission process:
• The atom is split into two or more smaller and lighter atoms.
• The byproduct of this process is that it produces many highly radioactive particles.
• But to generate this amount of particles you need a critical mass of the substance and high speed neutrons are required.
• This fission process takes little energy to split two atoms.
• The energy that is released is a million times greater than the energy released in chemical reactions, but lower than the amount of energy released by nuclear fusion.
• Uranium is the fuel that is used in the fission process.
Nuclear Fusion process:
• Fusing two or more lighter atoms into a larger one.
• Only a few of radioactive particles are produced.
• A high density and high temperature environment is required.
• Extremely high energy is required to fuse the atoms.
• The energy that is released is three to four times greater than the energy released by nuclear fission.
• Deuterium and tritium are the primary fuel used in fusion process.
Both fission and fusion processes are nuclear reactions that produce energy.
How is electricity generated from Nuclear power using nuclear fission process?
The whole process will be thoroughly explained via this paragraph extraction below (the reference will be listed at the end of the document):
“The reactor vessel (1) is a tough steel capsule that houses the fuel rods – sealed metal cylinders containing pellets of uranium oxide. When a neutron – a neutrally charged subatomic particle – hits a uranium atom, the atom sometimes splits, releasing two or three more neutrons. This process converts the nuclear energy that binds the atom together into heat energy.
The fuel assemblies are arranged in such a way that when atoms in the fuel split, the neutrons they release are likely to hit other atoms and make them split as well. This chain reaction produces large quantities of heat.
Water flows through the reactor vessel, where the chain reaction heats it to around 300°C. The water needs to stay in liquid form for the power station to work, so the pressuriser (2) subjects it to around 155 times atmospheric pressure, which stops it boiling.
The reactor coolant pump (3) circulates the hot pressurised water from the reactor vessel to the steam generator (4). Here, the water flows through thousands of looped pipes before circulating back to the reactor vessel. A second stream of water flows through the steam generator, around the outside of the pipes. This water is under much less pressure, so the heat from the pipes boils it into steam.
The steam then passes through a series of turbines (5), causing them to spin, converting the heat energy produced in the reactor into mechanical energy. A shaft connects the turbines to a generator, so when the turbines spin, so does the generator. The generator uses an electromagnetic field to convert this mechanical energy into electrical energy.
A transformer converts the electrical energy from the generator to a high voltage. The national grid uses high voltages to transmit electricity efficiently through the power lines (6) to the homes and businesses that need it (7). Here, other transformers reduce the voltage back down to a usable level.
After passing through the turbines, the steam comes into contact with pipes full of cold water pumped in from the sea (8). The cold pipes cool the steam so that it condenses back into water. It is then piped back to the steam generator, where it can be heated up again, turn into steam again, and keep the turbines turning. ”
How do you split the atoms in the fission process?
To split the Uranium atom you need to fire a neutron at the uranium atom so that it will stick to the uranium. When the neutron sticks to the uranium atom, it is making the uranium atom extremely unstable, which will lead to split the uranium atom up into two atoms and three neutrons. These atoms are barium and krypton.
The resulting particles will all have kinetic energy, and this energy comes from converting only a little of the mass of the original atom into energy which can be measured using:
E = mc2
This process is a continuous process which will not stop which is called a chain reaction, it will continue to split atoms forever until there is no more U – 235 atoms left to split.
How is the radiation contained at a nuclear power plant?
The radioactive materials that is fueling the power plant is contained inside a ceramic pellets, these pellets is encased in hollow metal rods to prevent any interaction with the coolant water inside the reactor. The reactor has thick metal walls and thick piping that prevent any radiation leakage. There is also a thick reinforced concrete dome all around the reactor core to keep the coolant, fuel, and radiation away from the environment.
What does the future hold for nuclear power plants in South Africa?
South Africa is planning to build 6 new nuclear power plants and will be operational by 2030. The total amount of cost of these 6 nuclear power plants will be between R400 billion to R1 trillion. The Energy minister Tina Joemat-Pettersson told the parliament that South Africa will start the nuclear power plant build program in 2015, to generate 9600 MW of electricity. The first unit will be commissioned by 2023.
But the international atomic agency says that South Africa is not prepared to expand the nuclear capability safely. Thus South Africa is sending 50 trainees to china and Russia for phase 1, nuclear training, and to send an additional 250 trainees to china to gain experience to run a nuclear power plant safely when South Africa is building a new power plant in the future.
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