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Type of Nuclear Power Plant

Type of Nuclear Power Plant

Nuclear power plant technology is designed for nuclear energy released from fission process can be utilized as a source of energy in everyday life. NPP is a system that uses power reactors in operation which acts as a heat-generating furnace. Today there are various types of nuclear power plants operating. The differences are marked with different types of power reactors that use. Each type of nuclear power plants / power reactor types generally developed by certain countries, so often a type of nuclear power plants are very prominent in a country, but not operated by other countries. Differences various types of power reactors that could lie in the use of fuel, moderator, type pendinging and other differences.

The different types of power reactors developed from country to country is also influenced by the level of technology associated with nuclear weapons by each country. In the early development of nuclear power plants in the 1950s, a new uranium enrichment could be carried out by the United States and Russia, so that the two countries at that time already begun to develop power reactor fuel is enriched uranium. Meanwhile in Canada, France and Britain at that time focused on reactor development program of natural uranium-fueled power. Therefore, the first nuclear power plant operating in three countries using natural uranium-fueled reactor. But in subsequent developments, especially Britain and France also operates the enriched uranium-fueled nuclear power plant.

Most power reactors are in operation today is the type of Light Water Reactor or LWR (Light Water Reactor) that originally developed in the U.S. and Russia. Called the Light Water Reactor by using high purity H2O as well as reactor coolant moderator material. This reactor consists of Water Reactor or PWR press (Pressurized Water Reactor) and BWR or BWR (Boiling Water Reactor) operated with total respectively reached 52% and 21.5% of the total operating power reactors. The remaining 26.5% consisted of various other types of power reactors. The following will be discussed further various types of nuclear power plants currently operating in different countries.

• Boiling Water Reactor

In boiling water reactor, fission heat is used directly to evaporate the cooling water and steam that is formed directly used to turn turbines. High pressure turbine receives steam at a temperature around 290 º C and pressure of 7.2 MPa. Some steam forwarded again to the low pressure turbine. With this system may be obtained by 34% thermal efficiency. Thermal efficiency indicates the percentage of fission heat that can be converted into electrical energy. After going through the turbines, steam will experience the cooling process so that changes to the water which goes to the reactor core to evaporated again and so on. In this reactor used fuel enrichment level of 235U by 3-4% in the form of UO2.

In 1981, the company Toshiba, General Electric and Hitachi collaborate with the company Tokyo Electric Power Co.. Inc. to launch a joint venture development project in order to improve system performance by introducing BWR Boiling Water Reactor Advanced or A-BWR (Advanced Boiling Water Reactor). Capacity A-BWR is designed to enhance greater economic benefits. In addition, some components of the reactor also increased, such as an increase in the fraction of fuel, improving the cooling system circulating pumps, control rod drive mechanism and others.

• Pressurized Water Reactor

Pressurized Water Reactor also using H2O as a coolant as well as moderator. The difference with BWR cooling is the use of two kinds, namely primary and secondary cooling. Heat generated by fission reaction is used to heat the primary cooling water. The reactor is equipped with pressure control equipment (pessurizer) used to maintain the primary coolant system pressure.

Pressurizer system consists of a tank equipped with electric heating and water sprayers. If the pressure in the reactor core is reduced, electric heater will heat the water contained in the pressurizer tank, forming additional steam which will raise the pressure in the primary cooling system. Conversely if the pressure in the primary cooling system increases, then the water spray system will condense some steam so that steam pressure is reduced and the primary cooling system will return to its original state. Pressure in the primary cooling system maintained at 150 Atm position to prevent the primary coolant water does not boil at temperatures around 300 º C. At normal air pressure, water will boil and evaporate at a temperature of 100 º C.

In the working process, the primary cooling water discharged into the steam generator system, causing heat exchange between the cooling system of primary and secondary cooling system. In this case between the two is simply cooling heat exchange occurs without any contact or mixing, because the two were separated by the cooling pipe system. The occurrence of heat exchange causes the secondary cooling water evaporates. Pressure on secondary cooling system is maintained at normal air pressure so that water can evaporate at a temperature of 100 º C. Steam formed in the steam generator system is then channeled to turn turbines.

From the above illustrated that the system work Pressurized Water Reactor nuclear power plant with more complex than the BWR systems. However, if viewed in the system safety, Pressurized Water Reactor is more secure than the BWR. In Pressurized Water Reactor primary coolant system of rotation actually closed, so if a leak of radioactive material inside the reactor core will not cause contamination of the turbine. Who’s in Boiling Water Reactor, leakage of radioactive material is dissolved in the primary cooling water can cause contamination of the turbine. Pressurized Water Reactor also has reliable operation and safety is excellent. One factor supporting this is because the reactor has a negative reactivity coefficient. If the temperature rise in the reactor core of a sudden, the reactor power will soon go down by itself. But because it uses two cooling systems, the thermal efficiency is slightly lower than the BWR.
• Heavy Water Reactor or HWR (Heavy Water Reactor)
Heavy Water Reactor is a type of reactor that uses D2O (heavy water) as moderator as well as cooling. These reactors use natural uranium fuel and should be used in heavy water absorbance of the neutron cross section is very small. Heavy water reactor nuclear power plant with the most famous is the CANDU (Canadian Deuterium Uranium) which was first developed by Canada. Just as tap water reactors, CANDU reactors also have primary and secondary cooling systems, steam generators and pressure control to maintain high pressure in the primary cooling system. D2O in the CANDU reactor is only used as a primary cooling system, while the secondary cooling system using H2O.

In the operation of CANDU reactors, D2O purity must be maintained at the level of 95 to 99.8%. Heavy water is an ingredient which was very expensive and physically and chemically indistinguishable directly with H2O. Therefore, the need for prevention efforts D2O leak either in the form of vapor or liquid. Flow ventilation of the room held in private and always monitored kebasahannya level, so the possibility of leakage can be known in early D2O.

• Magnox reactors or MR (Magnox Reactor)

Magnox reactors use fuel in the form of uranium metal or alloy that is inserted into the cladding alloy magnesium (Mg). The reactor was developed and many operated by the British. Included in this type of reactor is the world’s first research reactor built by Enrico Fermi led the team in Chicago, United States. Magnox reactors use CO2 as a coolant, graphite as moderator, and natural uranium as fuel. The heat of fission is taken by flowing CO2 gas through the fuel element into the steam generator system. From this heat exchange will produce water vapor which can then be used to turn turbines.

The results of efforts in improving performance is the introduction of the Magnox reactor Advanced Reactor Gas Cooled or Agr (Advanced Gas-cooled Reactor). In this reactor also uses CO2 as a coolant, graphite as a moderator, but the fuel is slightly enriched form of uranium wrapped in stainless steel cladding. Fuel enrichment is intended to increase thermal efficiency and fuel burn.

• High Temperature Reactor or HTR (High Temperature Reactor)

High Temperature Reactor is a type of reactor that uses helium gas coolant (He) and graphite moderator. This reactor is capable of producing heat to 750 º C with about 40% thermal efficiency. Heat generated in the reactor core was transferred using a cooling He (primary system) to the steam generator. In this steam generator heat will be absorbed by the steam system feed water (secondary system) and the resulting vapor flowed into the turbine. In this reactor there is also a system of separation between the radioactive primary coolant system and secondary cooling system that is not radioactive.

Fuel elements used in High Temperature Reactor-shaped balls, each element containing 192 grams of carbon, 0.96 grams and 10.2 grams of 235U 232Th which can be cultured into new fuel 233U. The process of fission in the reactor core capable of heating the gas until it reaches the temperature of 750 Uh _C. After exchanging heat with the secondary system, He gas temperature will drop to 250 º C. He then pumped more gas into the reactor core to take the heat of fission, and so on. In normal operation, these reactors require fuel ball diameter of 60 mm ± 675 000 eggs placed inside the reactor core. On average, each item of fuel remains in the porch for six months at full load operation.

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