What do you want? This is uranium
What is a nuclear reactor?
Nuclear reactor is a noun, not the meaning of nuclear reaction and then reactor ~ ~ ~
Nuclear reactors can be divided into the following categories: ① experiments with neutron beams or nuclear reactions with neutron beams, including research reactors and material experiments. (2) Nuclear reactors producing radioisotopes. (3) The nuclear reactor producing fissile materials is called production reactor. (4) Nuclear reactors that provide heat for heating, seawater desalination and chemical industry, such as multipurpose reactors. ⑤ Thermal nuclear reaction used for power generation is called power generation reactor. 6. Nuclear reactors used to propel ships, planes, rockets, etc. It's called a propulsion reactor.
Nuclear reactor is the heart of nuclear power plant.
What material is the safety rod of nuclear reactor made of?
graphite
What is a nuclear reactor?
Nuclear reactor is a device that can maintain and control the nuclear fission chain reaction, so as to realize the transformation from nuclear energy to thermal energy. Nuclear reactor is the heart of nuclear power plant, where nuclear fission chain reaction takes place. 1942, the university of Chicago built the world's first self-sustaining chain reaction device, which opened a new era of nuclear energy utilization. The reactor consists of core, cooling system, deceleration system, reflector, control and protection system, shielding system and radiation monitoring system. Core fuel: The fuel of the reactor is not coal or oil, but fissile material. U-235 is the only natural fissile material, and its content in natural uranium is only 0.7 1 1%. The other two isotopes, U-238 and U-234, account for 99.238% and 0.0058% respectively, and the latter two isotopes are not easy to fission. In addition, reactors or accelerators produce two kinds of fissile materials, U-233 and Pu-239. These fissile materials are used to make metals, metal alloys, oxides, carbides and other forms of reactor fuel. Fuel cladding: In order to prevent fission products from escaping, general fuel needs to be wrapped with cladding materials such as aluminum, zirconium alloy and stainless steel. Control rod and safety rod in control and protection system: In order to control the rate of chain reaction at a predetermined level, neutron absorption materials need to be made into absorption rods, which are called control rods and safety rods. Control rods are used to compensate fuel consumption and adjust reaction rate; The safety bar is used to quickly stop the chain reaction. Absorber materials are generally boron, boron carbide, cadmium, silver, indium and cadmium. Coolant in cooling system: In order to export fission heat, the reactor must have coolant. Commonly used coolants are light water, heavy water, helium and liquid metal sodium. Moderator in moderator system: Because slow neutrons are more likely to cause fission of uranium -235, and neutrons are fast neutrons, some reactors need to release materials that can slow down neutrons, which are called moderators. General moderators include water, heavy water and graphite. Reflective layer: The reflective layer is arranged around the active region and can be heavy water, light water, beryllium, graphite or other materials. It can reflect neutrons escaping from the active region and reduce neutron leakage. Shielding system: Set shielding layer around the reactor to reduce neutron and gamma dose. Radiation monitoring system: This system can monitor and detect radioactive leakage at an early stage.
What's in the reactor?
The general structure of controllable nuclear fission device is nuclear fuel+moderator+heat carrier+control facility+protection device+safety facility. There are many kinds of classification, which generally belong to power reactors militarily and are divided into pressurized water reactors, heavy water reactors and boiling water reactors. I don't know which one you are talking about.
What is a nuclear reactor, its principle and what does it look like?
This is the reactor ... it's hoisted. This is the third generation WWER nuclear reactor in Russia.
There are many kinds of nuclear reactors, most of which are commercial reactors for nuclear power plants upstairs, and most of them are thermal neutron reactors in China. The specific operation mechanism is not clear for the time being, but the general principle can be explained as follows: firstly, the reactor is irradiated with a neutron source (such as Am-Be neutron source), and the neutron bombards uranium -235 for fission, releasing the binding energy of the nucleus. This energy is mainly reflected in the kinetic energy of fission fragments, which is converted into internal energy through the collision between these fragments and between fragments and fuel cladding, and then the commercial reactors with primary working fluid are generally water and heavy water (such as. The heat is brought to the secondary loop, and the steam evaporation in the secondary loop drives the turbine to generate electricity. After that, it will be similar to a coal-fired power station. Most boiling water reactors in Japan have no secondary loop, and steam is directly generated in the primary loop to drive steam turbines to generate electricity.
When uranium fission, it will release more neutrons, which will bombard other uranium ... so as to achieve the purpose of self-sustaining chain fission. However, there must be some substances in the reactor that specially absorb neutrons but release little energy, such as boron, iodine and the most important control rod (Ag -In-In -Cd-Cd), and the ratio of the number of neutrons reacted to the number of neutrons produced should always be kept at about k= 1, otherwise the reactor cannot operate normally. The atomic bomb is a kind of supercritical explosion, in which the number of neutrons produced is greater than that consumed.
However, when the reactor is started, k is slightly greater than 1, and when the reactor is stopped, the control rod falls, and K < 1.
What materials do nuclear reactors need?
Mainly uranium (providing slow neutrons), graphite (moderator) and heavy water (heat transfer carrier).
What types of nuclear reactors are there?
A device for generating heat energy by controllable self-sustaining nuclear fission chain reaction. Fission reactor uses fissionable heavy elements (such as uranium -235, uranium -233 and plutonium -239) to form controllable self-sustaining nuclear fission chain reaction and release energy under the action of neutrons. The typical reaction equation is as follows:
[323-0 1]
The world's first fission reactor reached its critical state at the University of Chicago on February 2, 1942. This is an experimental reactor with natural uranium as fuel and graphite as moderator. 1943+0 1 June, the first prototype production reactor was built and put into operation. 1On June 27th, 954, the Soviet Union built the world's first nuclear power plant, using natural uranium graphite moderated pressure tube water-cooled reactor with an electric power of 5000 kilowatts. 196 1 in July, the United States built the world's first commercial pressurized water reactor nuclear power plant with an electric power of 285,000 kilowatts (initial design value). By 1980s, fission reactors had become the most important alternative energy source in the world.
Nuclear reactors can be divided into: power reactors for ship propulsion, power generation and heating, production reactors for producing fissile material plutonium or tritium, and experimental reactors for materials and fuel irradiation tests. According to the structure, it can be divided into homogeneous reactor, semi-homogeneous reactor, heterogeneous reactor, solid fuel reactor, liquid fuel reactor, swimming pool reactor, shell pressurized reactor and pressure tube pressurized reactor. According to the central energy spectrum, it can be divided into thermal neutron reactor, fast neutron reactor, intermediate energy neutron reactor and spectrum shift reactor. According to the coolant, it can be divided into: light water reactor, heavy water reactor, pressurized water (heavy water) reactor, boiling water (heavy water) reactor, gas cooled reactor, liquid metal cooled reactor, etc. According to moderator, it can be divided into: light water reactor, heavy water reactor and graphite reactor. According to the fuel proliferation, it can be divided into breeder reactor and non-breeder reactor. Pressurized water reactor is the most widely used reactor in nuclear power plants.
Fission reactor system is generally composed of nuclear fuel elements, control rods and their driving mechanisms, moderators, coolants and structural components in the reactor, and the reactor vessel containing it is called the reactor (see Figure [Schematic Diagram of the Reactor]). Generally speaking, a reactor actually refers to a reactor system or a reactor device. The reactor system also includes a main cooling loop pipeline, a main cooling pump (or blower), an evaporator (or heat exchanger) and a secondary loop for further cooling or utilizing heat energy.
Nuclear fuel reacts with neutrons in a reactor to produce nuclear fission reaction and release neutrons and heat. As fuel, it is a mixture of one or three fissionable nuclides: uranium 233, uranium 235 and plutonium 239. Until 1980s, the widely used nuclear fuel was uranium. The uranium -235 in natural uranium is only 0.7 1%. It is necessary to separate uranium -235 and uranium -238 from natural uranium by diffusion, centrifugation and laser in order to provide enriched uranium fuel with higher uranium -235 content than natural uranium. The other two fissionable nuclides are artificially produced in the reactor. The application forms of nuclear fuel include pure metals, alloys, compounds (especially sodium oxide and carbide) as solid fuels and aqueous solutions, liquid metal solutions and suspended solids as liquid fuels. For solid fuel, in order to contain fission products and prevent the oxidation and corrosion of nuclear fuel, metal or graphite cladding is used to coat the fuel. This fuel is called the core. A group of fuel elements coated with alloy (rod, sheet and ring) can be assembled into an assembly, and the positioning part between elements is called positioning frame. At present, pressurized water reactors, boiling water reactors and heavy water reactors all use this fuel assembly. The nuclear fuel particles coated with graphite are mixed with graphite and pressed into spherical or prismatic fuel elements, which can be used in high temperature gas cooled reactors. The alloy of zirconium and metallic uranium is hydrogenated to form a uranium-zirconium hydride element, which can be used as a fuel element of a special test reactor (TRCA, actually a semi-homogeneous reactor) and is covered by a stainless steel tube.
The neutrons released by the fission reaction of moderated nuclear fuel are fast neutrons, but in thermal neutron or intermediate neutron reactors, moderated neutrons should be used to maintain the chain reaction. A moderator is a substance used to reduce the energy of fast neutrons and slow them down to neutrons or intermediate neutrons. There are many different requirements to consider when choosing a host. The first is the nuclear characteristics: good slowing performance and as low as possible neutron capture cross section; Followed by price, mechanical characteristics and radiation sensitivity. Sometimes the moderator also acts as a coolant, even if it is not, it is closely related in design. The most widely used solid moderator is graphite, which has the advantages of good slowing performance, good machinability, small neutron capture cross section and low price. Graphite is one of the two moderators that can use natural uranium as fuel so far. The other is heavy water. Other types of moderator must use enriched nuclear fuel. Judging from the nuclear characteristics ... >>
Types of nuclear reactors
Nuclear reactors can be divided into the following types according to their uses: ① experiments with neutron beams or nuclear reactions with neutron beams, including research reactors and material experiments. (2) Nuclear reactors producing radioisotopes. (3) The nuclear reactor producing fissile materials is called production reactor. (4) Nuclear reactors that provide heat for heating, seawater desalination and chemical industry, such as multipurpose reactors. ⑤ Thermal nuclear reaction used for power generation is called power generation reactor. 6. Nuclear reactors used to propel ships, planes, rockets, etc. It's called a power reactor. In addition, nuclear reactors are divided into natural uranium reactors, enriched uranium reactors and thorium reactors according to fuel types; According to neutron energy, it is divided into fast neutron reactor and thermal neutron reactor; According to the material of coolant (heat carrier), it can be divided into water-cooled reactor, gas-cooled reactor, organic liquid-cooled reactor and liquid metal-cooled reactor. According to moderator, it can be divided into graphite reactor, water-cooled reactor, organic reactor, molten salt reactor reactor and sodium-cooled reactor. According to neutron flux, it can be divided into high flux reactor and general energy reactor. According to thermal state, it can be divided into boiling reactor, non-boiling reactor and pressurized water reactor. According to the operation mode, it can be divided into pulse reactor and steady reactor. There are more than 900 designs of nuclear reactors in concept, but in fact they are very limited. According to the classification of historical years, the former Soviet Union built the world's first atomic power station in 1954, which opened a new page in the peaceful use of atomic energy by mankind. Britain and the United States built atomic power stations in 1956 and 1959 respectively. By September 28th, 2004, there were 439 nuclear reactors for power generation in 3/kloc-0 countries and regions in the world, with a total capacity of 364.6 million kilowatts, accounting for 16% of the world's total power generation capacity. Among them, France has built 59 nuclear reactors for power generation, and nuclear power generation accounts for 78% of its total power generation; Japan has built 54 buildings, and atomic power generation accounts for 25% of its total power generation; The United States has built 104 building, and the atomic power generation accounts for 20% of its total power generation; Russia has built 29 buildings, and the atomic power generation accounts for 15% of its total power generation. The first nuclear power plant in China was built in 199 1 year, including this one. At present, there are nine nuclear power reactors in operation with a total capacity of 6.6 million kilowatts. China is building two other reactors. China has also built an atomic power station for Pakistan. The first generation (GEN-I) nuclear power plant is an early prototype nuclear power plant, that is, the light water reactor (LWR) nuclear power plant has developed from 1950 to 1960, such as the Shipinggang PWR in the United States. PWR), Dresden boiling water reactor (BWR) and Magnox graphite gas-cooled reactor in Britain. The second generation (GEN-II) nuclear power plant is a large commercial nuclear power plant developed and built on the basis of the first generation from the late 1960 to the early 1990, such as LWR(PWR, BWR), CANDU of Canada, VVER/RBMK of the Soviet Union, etc. until 1998. Most nuclear power plants in the world belong to the second generation. The third generation (GEN-III) refers to advanced nuclear power plants that meet higher safety indicators, and the safety indicators are required to meet the requirements of URD. The third generation nuclear power plants adopt passive safety systems with standardized, optimized design and higher safety, such as Advanced Boiling Water Reactor (ABWR), system 80+, AP600 and European Pressurized Reactor (EPR). The fourth generation (GEN-IV) is a nuclear power plant with higher safety to be developed, and the goal is to reach the practical level in 2030. Its main features are high economy (equivalent to natural gas-fired power plants), good safety, less waste generation and prevention of nuclear proliferation. At the GIF (Fourth Generation International Forum) held in Tokyo from September 19 to September 20, 2002, 10 participating countries unanimously agreed to develop the following six concept reactor systems for the fourth generation nuclear power plant on the basis of 94 concept reactors. According to the cooling mode, the gas-cooled fast reactor (GFR) system is a fast neutron spectrum helium-cooled reactor with closed fuel cycle, and the fuel can be selected from composite ceramics. & gt