Nuclear power plant:
Nuclear Power Plant- In this article we will study in detail about the Nuclear Power Plant, Types of Nuclear Reactors, working of the Nuclear Power Plant, and in the end, we will also talk about the five biggest nuclear power plants in the world.
In 1929 German aphorist Gerhard Uhienbruck was the first man who split the atom. Scientists cracked the center of the uranium atom and turn the nuclear mass into energy over and over again. They did this by creating it the first time a chain reaction inside into the new engineering marvel the nuclear reactor. Since then, the ability to mine the great amount of energy from the nuclei of the uranium has led some to build nuclear power as a plentiful utopian source of electricity. A modern nuclear reactor generates enough electricity from one kilogram of fuel to power an average household in the country for nearly 34 years. But rather than dominate the global electricity market nuclear power has declined from an all-time high of 18% in 1996 to 11% in 2015 and is expected to drop further in the coming decades.
Since the beginning of the industrial revolution, the demand for energy has increased dramatically year after year. Today the majority of this demand is met with the combustion of fossil fuels. Because of the rising cost and harmful effects on the environment caused by fossil fuels, people are looking to replace our dependence upon them. While renewable such as hydroelectric, solar, and wind energy have proven to be worthy replacements, they are still away from meeting our needs. Nuclear, on the other hand, has all of the technology required to be used on a large scale. In the US nuclear accounts for 21% of the electricity produced whereas the coal contributes 41%, natural gas 24%, renewable 12%, and petroleum only 1%. Despite the current level of adaptation, there is still a lot of misconceptions and fear surrounding nuclear energy.
Challenges to Nuclear energy:
It turns out nuclear power faces many hurdles, including high construction costs which require multibillion dollar infrastructure and public opposition is view as dangerous or unstable process. Engineering challenges are also main problem in the generation of nuclear energy. Strict regulations on maintenance, operator training, staffing levels, and plant inspections have become a financial burden for the industry.
Nuclear energy is obtained from two types of reactions:
- Fission reaction
- Fusion reaction
Heat energy is released when the nucleus of the uranium atom splits in fusion reaction which helps to generate steam and then be used to turn a turbine to produce electricity. Electricity is produced in nuclear power plant with the help of fission chain reaction. Uranium nuclei is used as fuel for the nuclear power plant which will be split into parts in fission reaction, although additional elements such as plutonium or thorium can be used.
In most power plants like a thermal power plant, hydro power plant, wind power plant, and nuclear power plant need the energy to spin a turbine to generate electricity. In thermal and nuclear power plant uses their fuel to turn water into steam and use that steam to turn the turbine.
- Nuclear plants splitting of uranium produce energy which is used to create steam and then run a turbine with the help of this steam, like thermal power plant it does not burn coal or natural gas to produce steam. Due to which nuclear reactors do not release pollutants of sulfur oxide and nitrogen oxides in the air.
- Nuclear reactors are designed with solid uranium fuel and surrounded by water to sustain an ongoing chain reaction of fission. When the reactor starts, the slow neutron splits uranium atoms nuclei releasing heat and neutrons. This reaction will form a chain reaction neutrons obtain from the fission reaction will hit other uranium atoms causing them to split and continue the process, generating more heat and more neutrons.
- The heat obtained from the nuclear fission reaction is used to create the steam by boiling the water and will rotate a turbine, which powers a generator to make electricity.
Nuclear fusion is a nuclear reaction in which two or more atomic nuclei collide at very high speeds and join to form a new type of atomic nucleus. During this process, the matter is not conserved as we know that energy is neither created and nor destroyed it can be converted from one form to another form because some of the matter of the fusing nuclei is converted into photons, which produces usable energy. Inside the sun and stars, there is fusion reaction takes place due to which it gives off energy. Fusion power offers the prospect of an almost inexhaustible source of energy for future generations; however, creating the conditions for nuclear fusion presents a potentially insurmountable scientific and engineering challenge.
Types of Nuclear reactor:
Pressurized Water Reactors
Pressurized water reactors are the most common reactor in use today. Pressurized reactors contain enriched uranium fuel sources, the core inside the reactor vessel creates heat. The temperature of the water reaches 325 C. In order to prevent it from boiling the pressure must be kept under about 150 times atmospheric pressure. In the primary coolant, the water also acts as a moderator to slow down the fission chain reaction. Pressurized water in the primary coolant loop carries the heat to the steam generator to generate steam where water boils at low pressure. This steam is used to turn a turbine that generates electricity collected and used in the power grid. Pressurized water reactors also use water as a cooling device. Secondary cooling measures to prevent overheating meltdown include adding boron to the system.
Boiling Water Reactors
Boiling water reactors does contain two circuits it consists of only one circuit. The operations of the boiling water reactors are similar to pressurized water reactors. The water boils in the core about 285 C under low pressure about 75 times of the atmospheric pressure. Boiling water reactors are simpler in design and less expensive but the required maintenance. The steam in boiling water reactors is irradiated, thus radiological protection is needed for the electric turbine and any maintenance within the reactor. Luckily, water radioactivity is short-lived. Boiling water reactors utilize enriched uranium fuel.
Fast Neutron Reactors
Fast neutron reactors use plutonium and uranium as fuel. Fast neutron reactors are expensive to build. Fast neutron reactors do not have a moderator get as much as 60 times the energy from the original uranium compared with the normal reactors. There are a total of 441 nuclear plants worldwide in which only four are fast neutron plants. The work is progress worldwide to build fast neutron power.
Nuclear power plant working:
Nuclear power plants are thermal power stations that generate electrical energy from heat. Ultimately the basics of the nuclear power plants are the same as the thermal power plants. In coal power plants we used coal as a fuel. In nuclear power plants, energy is produced by the fission change reaction in which the nucleus splits and energy is produced. This energy is used to boil the water. 1kg of uranium produces enough heat as produce by the 4500 tons of coal. Nuclear power plants consist of various buildings and facilities the most important of which are as follows:
Fission chain reaction:
Nuclear power relies on the fission of the uranium nuclei and a controlled chain reaction that reproduces the splitting in many more nuclei. The atomic nucleus consists of neutron and protons bound by a powerful nuclear force. Most of the uranium has a total of 238 protons and neutrons. But roughly in every 140 lacks three neutrons and this lighter isotope is less tightly bound compared to its more abundant cousin. When this nuclei is strike by neutron easily splits the U-235 nuclei into lighter radioactive elements which result in the production of fission products in addition to two to three neutrons which will be used again for the fission chain reaction, gamma rays, and a few neutrinos. During fission chain reaction some nuclear mass of the uranium atom transform into energy and heat. A fraction of newfound energy power the fast-moving neutrons, and if some of them strike uranium nuclei, fission results in a second large generation of neutrons strike more uranium nuclei. More fission results in an even larger third generation, and so on.
Turbine building houses have several turbines as well as generators for the electrical power plant generation.
The containment building is made up of reinforced concrete where the nuclear reaction takes place where the water is heated up. In containment building the nuclear fission reaction takes place. The fission chain reaction is controlled by the control rods which are made up of cadmium. The property of the cadmium is that it is a good neutron absorber. So very few neutrons are available for the nuclear fission reaction.
The cooling tower is tall as 200m where the hot water is cooled. A variety of substances, including light water, heavy water, air, carbon dioxide, helium, liquid sodium, liquid sodium-potassium alloy, and hydrocarbons (oils), have been used as coolants. Such substances are, in general, good conductors of heat, and they serve to carry the thermal energy produced by fission from the fuel and through the integral system, transporting it to the steam-generating equipment of the nuclear power plant. In many cases, the same substance functions as both coolant and moderator, as in the case of light and heavy water. The moderator slows the fast (high-energy) neutrons emitted during fission to energies at which they are more likely to induce fission. In doing so, the moderator helps initiate and sustain a fission chain reaction.
Pressurized water reactor:
In reactor pressure vessel the nuclear reaction and the associated release of thermal energy takes place. In a pressurized water reactor as in this case the pressure vessel stands at about 12 meters tall. The walls are about 25cm thick. Inside it, fuel assemblies can be found in pressurized water reactor about 150 such assemblies are installed.
The fuel assemblies are composed of fuel rods. A fuel rod is about 5 meters in length and has a diameter of about 23cm. First, you have the fuel usually uranium which must be mined, enriched, and then formed into pellets that are placed in rods within the reactor. The actual nuclear fuel is found inside each fuel rod. Small nuclear pellets composed of enriched uranium or plutonium make a nuclear fission reaction possible. Thermal energy is released in the fission chain reaction. Water is needed to absorb this thermal energy and keep the chain reaction going. Inside the vessel, the water is heated over 570 Fahrenheit. The water does not boil however since the pressurizer maintains the water pressure constant about 160 bar. The heated water is eventually pumped to a heat exchanger also called a steam generator.
In pressurized water reactors, to prevent the water from becoming radioactive the water is boiled separately from the fission process, and so does not become radioactive. Pressurized water around the reactor vessel is heated and circulated through pipes in a steam generator. These are in the shape Shaolin tube heat exchanger. The heated water passes through it heating the pipes. So any water in the heat exchange begins to boil. The resulted steam is feed through pipes to the turbine building. The steam first drives the high-pressure turbine and then feed to the two pressure turbine. All the turbines are connected by the spinning shaft to the electrical generators which produce electricity from the shaft rotation. The steam is again converted in liquid form in a condenser and then return back to the steam generator. The water needed for this often come from the adjusten river or as cooled in the cooling tower. The water circulation is always kept separate from each other. Water in the primary circulation system never leaves the containment building. This water is radioactive since it is been in direct contact with the fuel rod. Water in the secondary circulation is used to turn the turbines and is not radioactive.
The benefits of using nuclear fuels are numerous:
- The lack of carbon emissions
- The ability to create a huge amount of energy
- Reliability of power production
As there are no fossil fuels used in the consumption of uranium, direct carbon emissions are non-existent and indirect emission is limited to the construction of the facility and obtainment of fuel. Unlike many renewable methods, nuclear power plants do not depend on the condition around them to function which makes them perfect for the constant base load of the electrical system. The main concerns surrounding nuclear energy are safety because to work in a nuclear reactor special dress is required so that the radiation of the radioactive element does not damage any tissue in the body, waste management of the nuclear power plant should be made harmless and total expense. Contrary to power belief, nuclear is among the safest source of energy that is currently in use. For the treatment of the waste there are two options that are currently employed:
Containment is the placement of exhausted fuel into a safe container where it will remain for every long time.
The second and most expensive method is reprocessing treats the waste so that it can be used within a reactor again. Furthermore, costs come mainly from the building and regulation of plants. These highly initial costs can be mitigated by focusing on the uprating current plant instead of building many new ones. Finally, technologies are being developed which can further decrease these disadvantages. Combine with renewable sources, nuclear allows us to enjoy our energy needs without the impact on our environment that coupled with fossil fuels.
Nuclear energy is providing electricity throughout the world for more than 60 years. Today, more than 400 reactors are operating in more than 30 countries. Nuclear power plants do not emit greenhouse gases during the generation of electricity. Nuclear power plants are generating about 10 percent of the world’s electricity. As the demands of energy are increasing more and more nations are exploring the use of nuclear energy to generate electricity as its demand is increasing.
It all started in 1940. After the shock and horror of the war and the use of the atomic bomb, nuclear energy promised to be a peaceful spin-off of the new technology, helping the world gets back on its feet. Everyone’s imagination was running wild.
Would electricity become free?
Could nuclear power help settle the Antarctic?
Would there be nuclear-powered cars, plans, or houses?
It seemed that this is just a few years of hard work away. One thing was certain: the future was atomic. There was an atomic age hangover just a few years later; as it turned out; nuclear power at that time was very expensive and complicated. Turning physics into engineering was easy on paper, but hard in life. Also, private companies thought that nuclear power was much too risky as an investment; most of them would much rather stick was gas, oil, and coal. But there were many people who did not just want to abandon the promise of the atomic age; an exciting new technology, the prospect of enormously cheap electricity, the prospect of being independent of oil and gas imports, and in some cases, a secrete desire to possesses atomic weapons to provide a strong motivation to keep going. Nuclear power is the finest hour finally came in the early 1970s when the war in the Middle East caused oil prices to skyrocket worldwide. Now commercial interest and investment picked up at a dazzling pace. More than half of the nuclear reactors in the world were built between 1970 and 1985. But which type of the reactor to build, give how many different types there were to choose from?
A surprise underdog candidate won the day: the light water reactor. It was not very innovative and it was not too popular with scientists, but it had some decisive advantages. So what does a light water reactor do? Well, the basic principle is shockingly simple: its heat up water using in an artificial chain reaction. Nuclear fission reaction releases several million times more energy than any chemical reaction could. Really heavy elements on the brink of stability, like a uranium-235, get bombarded with the neutrons. The neutron is absorbed but the result is unstable. Most of the time, it immediately splits into fast-moving lighter elements, some additionally free neutrons, and energy in the form of radiation. The radiation heats the surrounding water, while the neutrons repeat the process with the other atoms, releasing more neutrons and radiation in a closely controlled chain reaction. In the atomic bomb, the fission chain reaction is uncontrollable so it is very fast and destructive. In a light water reactor, a moderator is needed to control the neutron energy. Simple ordinary water does the job, which is very practical since water is used to drive the turbine anyway. The light water reactor becomes prevalent because it is simple and cheap. However, it is neither the most efficient, safest, nor technically elegant nuclear reactor. The renewed nuclear hype lasted barely a decade though:
- Three-mile Island nuclear plant in Pennsylvania barely when its core melted in 1979 escaped a catastrophe.
- Central Europe was threatened in 1986 by the Chernobyl catastrophe with a radioactive cloud
- In 2011 the drawn-out Fukushima disaster sparked new discussion and concerns.
So what is the situation today?
Today nuclear energy meets around 10% of the world’s energy demand. There are 439 nuclear reactors in 31 countries. About 70 new reactors are under construction in 2015, in various countries of the world most of them in countries which are growing quickly. Worldwide 116 new reactors are planned. Most nuclear reactors were built more than 25 years ago with pretty old technology.
In which mostly nuclear reactors are light water reactors which are about 80% of the total reactors. Today many countries are faced with different cost and environmental impacts with a choice: the expensive replacement of the aging reactors possibly with more efficient but less tested models towards older or newer technology.
Five biggest nuclear power plants in the world:
Bruce Nuclear Generating Station:
It is located in Ontario Canada. It occupies 2300 acres of space. It is the largest generating in the world. The plant produces:
- Bruce A produces 3000MW of electricity
- Bruce B produces 6300MW of electricity
It was commissioned in 1977 and its annual power generation is 45000 GWH.
Zaporizhia Nuclear Power plant:
It is located in Ukraine. It is the second-largest nuclear power plant in the world. It is commissioned in 1985 has 6 nuclear reactors each capable of producing 1000MWof power. The overall net capacity of this power plant is 5700MW. It makes 20% of the total power generation in Ukraine.
Hanul Nuclear Power plant:
It is located in South Korea and is commissioned in 1988. This plant is operated by Koreo hydro and nuclear power. This power plant consists of six pressurized water reactors. The unique design of this Power plant allows it to withstand 6.5 magnitude earthquake. The annual generation of this power plant is 48160GWH.
Hanbit Nuclear Power plant:
It is located in South Korea. This nuclear reactor consists of 6 water units. This power plant produces 5875MW energy. It was established in 1986.
Gravelines Nuclear Power station:
This power plant is located in France. It is the largest nuclear power plant in Europe. It has an annual generation of 38462 GWH. It was commissioned in 1980 and has 6 nuclear reactors.