1. Military use
(1) The use of nuclear energy is first of all in the military, manufacturing nuclear energy weapons
Nuclear energy weapons are the general term for weapons that use nuclear energy to self-sustain the energy released by nuclear fission or fusion reactions to produce explosive effects and have mass destruction and destruction effects. Among them, fission weapons made mainly by the principle of fission chain reaction of heavy nuclei such as U235 or plutonium 239 are called atomic bombs; thermonuclear weapons made mainly by the principle of thermonuclear reaction of light nuclei such as heavy hydrogen (deuterium) or superheavy hydrogen (tritium) It is called hydrogen bomb, also known as fusion bomb and thermonuclear bomb. The power of an atomic bomb is usually a few hundred to tens of thousands of tons of TNT equivalent, and a hydrogen bomb can be as large as tens of thousands of tons of TNT equivalent.
Atomic bombs are also known as nuclear bombs and fission bombs. Its shape is similar to an ordinary blockbuster but its structure is completely different. It is mainly composed of nuclear charge (nuclear fuel), detonator, neutron reaction layer, neutron source and cartridge case. Nuclear fuel is a high-concentration fission material divided into small pieces. The atomic bomb first uses high-efficiency explosives to compress two or more pieces of high-concentration nuclear fuel in a critical state from two or all sides in a very short time to reach an instant, highly supercritical state. There is no moderator in the atomic bomb. The lifespan of each generation of neutrons can be as short as one hundred millionths of a second. A large number of atomic nuclei fission, releasing huge energy to achieve the purpose of explosion.
For the needs of the Second World War, the atomic bomb was made before Nazi Germany. From 1941 to 1945, the United States lasted 5 years, mobilizing a total of 500,000 people, 10,000 scientists and engineers, and costing 2 billion U.S. dollars. Electricity accounts for 1/3 of the electricity in the United States for the development of atomic bombs. The actual manufacture of the atomic bomb was not completed in 1943 under the leadership of the scientist Oppenheimer who was later known as the "father of the atomic bomb." On July 16, 1945, the first US atomic bomb was successfully tested. On August 6th and 9th, the US government dropped two atomic bombs on Hiroshima and Nagasaki, Japan, forcing the Japanese imperialists to surrender.
Due to the tremendous destructive power of the atomic bomb, it became an important strategic weapon during the Cold War. Before 1949, the Soviet Union, the United Kingdom in 1952, France in 1961, China in 1964, and India in 1968 exploded their own atomic bombs or nuclear devices. After the war, nuclear armaments intensified. According to information released by the United Nations, there were 10,000 nuclear warheads in the world, with an explosive equivalent of about 15 billion tons of TNT explosives. Everyone in the world would be threatened by a nuclear equivalent of 3 tons of TNT explosives. Therefore, some people called atomic bombs. It is "an invention that destroys the earth."
(2) The second military application of nuclear energy is to produce nuclear power
Nuclear power is the power obtained by using controllable nuclear reactions to obtain energy. The most typical applications powered by nuclear energy are nuclear submarines and nuclear-powered aircraft carriers. After the war, the United States began to implement its nuclear submarine program. In January 1954, the first US nuclear submarine was launched.
Compared with ordinary submarines, the difference of nuclear submarine is that it changes the power source to nuclear power plant, and its nuclear power is actually a reactor. Because the reactor operation does not require surface and underwater air, nor does it need to carry a large amount of fuel, nuclear submarines leave conventional submarines far behind in terms of endurance, surface and underwater navigation speed, and diving time, and become naval weapons. The best in it.
As of 1990, there were 505 nuclear submarines in the United States, the former Soviet Union, the United Kingdom, France and other countries. Most nuclear submarines in the former Soviet Union adopted the dual-reactor approach.
The Electric Ship Department of General Dynamics of the United States spent 4 years and spent more than 3 billion US dollars to successfully develop the world’s latest attack nuclear submarine. The US Navy named it the "Sea Wolf". It is currently the smallest, fastest, and deepest diving submarine. One of the nuclear submarines, an attack nuclear submarine that integrates modern high-tech technologies like the "Seawolf", will play a key role in the anti-submarine strategy in the 21st century.
The military applications of nuclear energy and nuclear technology include nuclear-powered aircraft carriers and nuclear-powered rockets. But after World War II, nuclear energy began to be transferred to peaceful uses on a large scale.
2. Use nuclear energy to generate electricity
(1) Nuclear power generation
At present, the proportion of fossil fuels in energy consumption is still in an absolute advantage, but this energy not only has a low combustion utilization rate, but also pollutes the environment. The harmful gases such as carbon dioxide released by its combustion can easily cause the "greenhouse effect" and make the earth's temperature The increase year by year causes an abnormal climate, accelerates the process of land desertification, and has a serious impact on the sustainable development of society and economy. Compared with thermal power plants, nuclear power plants are very clean energy sources. They do not emit these harmful substances and will not cause the "greenhouse effect". Therefore, they can greatly improve the environmental quality and protect the ecological environment on which humans depend.
In the world, many years of statistics from nuclear power countries show that although the investment in nuclear power plants is higher than that of coal-fired power plants, the cost of nuclear fuel is much lower than that of coal. On the contrary, the energy released by nuclear fuel reaction is much higher than that of fossil fuel combustion. The energy released, and nuclear fuel is inexhaustible, which makes the current total power generation cost of nuclear power plants lower than coal-fired power plants.
Nuclear power generation is the most extensive and main application form of nuclear energy. It uses the heat released by nuclear fission in a nuclear reactor to heat water to high temperature and high pressure, and the steam generated is used to drive a steam turbine and drive a generator to generate electricity.
Nuclear power generation is very similar to thermal power generation. Only nuclear reactors and steam generators are used to replace thermal power boilers, and nuclear fission energy is used to replace the chemical energy of fossil fuels. Nuclear power generation uses the heat generated by the chain reaction of nuclear fission using uranium fuel to heat water into high temperature and high pressure, and uses the generated water vapor to drive a steam turbine and drive a generator. Except for boiling water reactors, other types of power reactors use the primary loop coolant to heat through the core, transfer the heat to the secondary or tertiary loop water in the steam generator, and then form steam to drive the turbine generator. The boiling water reactor is the primary loop of the coolant that is heated by the core to become saturated steam at about 70 atmospheres, which is separated and dried to directly drive the steam turbine generator. The history of nuclear power generation is closely related to the history of power reactor development. The development of power reactors was originally due to military needs. In 1954, the Soviet Union built the world's first nuclear power plant with an installed capacity of 5 megawatts (electricity). The United Kingdom, the United States and other countries have also built various types of nuclear power plants. By 1960, 5 countries had built 20 nuclear power plants with an installed capacity of 1279 MW (electricity).
The heat released by nuclear reactions is much higher than the energy released by burning fossil fuels (a difference of about a million times). In comparison, the fuel volume required is considerably less than that of thermal power plants. The purity of uranium-235 used in nuclear power generation is only about 3%-4%, and the rest is uranium-238 that cannot produce nuclear fission. For example, the fourth nuclear plant consumes 80 tons of nuclear fuel every year, and only 2 standard containers can be carried. If you switch to coal, you need 5.15 million tons, and you need to use a 20-ton truck to transport 705 vehicles per day. If natural gas is used, 1.43 million tons are required, which is equivalent to burning 200,000 barrels of household gas every day. In other words, it is just close to the gas consumption of 6.92 million households in Taiwan.
The process of nuclear power generation
The process of nuclear power generation can be represented by simple and vivid diagrams:
Nuclear energy → internal energy of water and water vapor → mechanical energy of generator rotor → electrical energy.
(2) Principles of nuclear power generation
The energy of nuclear power generation comes from the fission energy released by the fission reaction of the fissionable material (nuclear fuel) in the nuclear reactor. Fission reaction refers to the process in which heavy elements such as uranium-235, plutonium-239, and uranium 233 are split into two fragments under the action of neutrons, and neutrons and a large amount of energy are released at the same time. During the reaction, the nucleus of the fissionable material absorbs one neutron and fisses and releases two or three neutrons. If these neutrons are removed and consumed, at least one neutron can cause another atomic nucleus to fission, making the fission self-sustaining, then this reaction is called a chain fission reaction. The realization of chain reaction is a prerequisite for nuclear power generation.
(3) The main advantages and disadvantages of nuclear power generation
The main advantages of nuclear power generation are:
① It will not cause air pollution and is a clean way of generating electricity;
② Will not produce carbon dioxide that aggravates the global greenhouse effect;
③The uranium fuel used in nuclear power generation has no other purpose except power generation, and coal, oil, natural gas for thermal power generation, and water resources for hydropower generation have other uses;
④ Nuclear fuel has high energy density, the fuel used by nuclear power plants is small, and it is very convenient for transportation and storage. A 1,000-megawatt nuclear power plant only needs 30 tons of uranium fuel a year, which can be transported by an aircraft on a single voyage;
⑤The cost of nuclear power generation is relatively low in fuel costs, and the cost of power generation is more stable than other power generation methods.
Of course, nuclear power generation also has its disadvantages:
①The investment cost of nuclear power plant is too large;
②The thermal efficiency of nuclear power plants is low, so more waste heat is discharged into the environment than ordinary fossil fuel power plants, so the thermal pollution of nuclear power plants is more serious;
③Nuclear power plants are less suitable for peak and off-peak on-load operation;
④Nuclear power plants will produce radioactive waste or used nuclear fuel. Although it occupies a small volume, it must be handled carefully because it is radioactive;
⑤ There are a large amount of radioactive materials in the reactor of nuclear power plant. If they are released into the external environment in an accident, it will cause harm to the ecology and the people.
(4) The history of nuclear power generation
Nuclear power generation has a history of more than 50 years. The history of nuclear power generation is closely related to the history of power reactor development. The development of power reactors was originally due to military needs.
In 1949, the Atomic Energy Commission announced the selection of a place in Idaho as the national nuclear power plant test station. On December 20, 1951, in Arco, Idaho, the breeder reactor generated electricity from nuclear power for the first time, lighting four lights. On March 30, 1953, the Nautilus used nuclear power to generate electricity for the first time. In 1954, the Soviet Union built the world's first nuclear power plant with an installed capacity of 5 MW(e), the Obrinsk Nuclear Power Plant. It opened a new era for the peaceful use of nuclear energy by mankind. Its completion marked the second energy revolution of mankind. Start.
As a new energy source, nuclear power generation has been valued by countries all over the world. Subsequently, the United Kingdom, the United States and other countries have successively built various types of nuclear power plants. On July 12, 1957, with the help of an experimental sodium reactor in Santa Susanna, California, people realized nuclear power generation for the first time in a civilian power station (this nuclear power plant operated until 1966). In 1957, the first commercial nuclear power station was established near Shipping Harbor, Pennsylvania. Three weeks later, the nuclear power plant began to supply electricity to the Pittsburgh area. On October 15, 1959, the first nuclear power plant in the United States without any government funding was completed. The Power Plant No. 1 in Dresden, Illinois, realized a self-supplied nuclear energy response. In the early 1960s, for the first time, people built small nuclear power plants in remote areas to power weather stations and illuminate buoys for navigation. By 1960, 5 countries had built 20 nuclear power plants with an installed capacity of 1279 MW (electricity). On April 3, 1965, the United States put into use the first aerial nuclear reactor. Due to the development of nuclear enrichment technology, by 1966, the cost of nuclear power generation was already lower than the cost of thermal power generation. Nuclear power generation has truly entered the practical stage.
In 1978, there were more than 200 nuclear power plant reactors of more than 30 MW(e) in operation in 22 countries and regions around the world, with a total installed capacity of 107,776 MW(e). In the 1980s, due to the increasingly prominent shortage of fossil energy, nuclear power generation progressed faster. In 1989, there were 109 nuclear power plants in the United States, setting a record for power generation, surpassing the total power generation of all fuels in 1956, supplying 19% of the country's electricity, 58 nuclear power plants in France; 52 nuclear power plants in Japan; Britain There are 35 nuclear power plants Russia has 29 nuclear power plants; China's nuclear power generation has just started; four existing nuclear power plants have been put into operation to generate electricity. By 1991, nearly 30 countries and regions around the world had built 423 nuclear power plants with a total capacity of 327.5 million kilowatts, and their power generation accounted for about 16% of the world's total power generation. According to statistics in 1995, there are more than 500 nuclear power plants in the world, and nuclear power accounts for 23.16% of the world's electricity generation.
Nuclear power generation is quite safe, environmentally friendly and economical. Nuclear energy is gradually replacing various other energy sources. The fuel cost of nuclear power plants is much lower than that of thermal power plants. For a 1 million kilowatt pressurized water reactor nuclear power plant, 40 tons of fuel need to be supplemented each year, of which only 1.5 tons of uranium-235 are consumed, and the rest can be recovered. So fuel transportation is trivial. For a power plant that burns 1 million kilowatts of coal, it consumes at least 2.12 million tons of standard coal each year. On average, a 10,000-ton ship or three 40-carriage trains transport coal to the power plant every day. The heavy burden of transportation is conceivable. Nuclear power plants are giants in the energy queue. A 1 million kilowatt-class PWR nuclear power plant needs only 30-40 tons of low-enriched uranium nuclear fuel a year, while a coal power plant of the same scale will supply it with 2.12-3.5 million tons of coal a year.
So far, there are 436 nuclear power plants in operation in the world, with a total installed capacity of 372 million kilowatts, accounting for 17% of the world's total installed capacity. Among the countries in the world, France has the fastest growing nuclear power plants, with 57, with a total installed capacity of 62 million kilowatts, and nuclear power accounts for 77.8% of the total power generation.
Nuclear power in mainland China started relatively late, and construction of nuclear power plants started in the 1980s. China's first nuclear power plant designed and manufactured by China, the Taishan 300,000-kilowatt pressurized water nuclear power plant, was successfully connected to the grid for power generation on December 15, 1991. The grid-connected power generation of Taishan Nuclear Power Plant is an important milestone in China's nuclear power industry. It marks the end of the history of non-nuclear power in mainland China, and it also marks that China has the ability to design and manufacture nuclear power plants. Guangdong Shenzhen Daya Bay Nuclear Power Plant started construction in 1987 and was all connected to the grid for power generation in 1994. Tianwan Nuclear Power Station is located in Lianyungang City, Jiangsu Province. It has a dual-digital I&C system and a double-layer containment. The Guangdong Lingao Nuclear Power Station was put into operation in 2005, constructed in 1995, and put into operation on May 29, 2002.
China has built a total of 11 nuclear power units with a total installed capacity of 9.1 million kilowatts, accounting for 1.1% of the country's total installed capacity, which is very far from the 17% in the world. China's "2007 Medium and Long-term Development Plan for Nuclear Power" has set a goal of 40 million kilowatts of nuclear power installed capacity by 2020, and the current nuclear power plants that have been built and are under construction have reached 36 million kilowatts. As the cleanest and most economical way of generating electricity, nuclear power is currently one of the most suitable renewable energy methods for development. According to experts from relevant departments, the country is likely to increase the target of nuclear power installed capacity in 2020 to 80 million kilowatts in the near future. Nuclear power in the next 10 years The total investment in the industry will reach 980 billion yuan, and it will usher in a peak in 2011-2012.