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Pressurizer (nuclear Power)
A pressurizer is a component of a pressurized water reactor. The basic design of the pressurized water reactor includes a requirement that the coolant (water) in the reactor coolant system must not boil. Put another way, the coolant must remain in the liquid state at all times, especially in the reactor vessel. To achieve this, the coolant in the reactor coolant system is maintained at a pressure sufficiently high that boiling does not occur at the coolant temperatures experienced while the plant is operating or in any analyzed possible transient state. To pressurize the coolant system to a higher pressure than the vapor pressure of the coolant at operating temperatures, a separate pressurizing system is required. This is in the form of the pressurizer. Design In a pressurized water reactor plant, the pressurizer is basically a cylindrical pressure vessel with hemispherical ends, mounted with the long axis vertical and directly connected by a single run of piping to the re ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pressurized Water Reactor
A pressurized water reactor (PWR) is a type of light-water reactor, light-water nuclear reactor. PWRs constitute the large majority of the world's nuclear power plants (with notable exceptions being the UK, Japan and Canada). In a PWR, the primary nuclear reactor coolant, coolant (water) is pumped under high pressure to the reactor core where it is heated by the energy released by the Nuclear fission, fission of atoms. The heated, high pressure water then flows to a Water-tube boiler, steam generator, where it transfers its thermal energy to lower pressure water of a secondary system where steam is generated. The steam then drives turbines, which spin an electric generator. In contrast to a boiling water reactor (BWR), pressure in the primary coolant loop prevents the water from boiling within the reactor. All light-water reactors use ordinary water as both coolant and neutron moderator. Most use anywhere from two to four vertically mounted steam generators; VVER reactors use horizo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pressurized Water Reactors
A pressurized water reactor (PWR) is a type of light-water nuclear reactor. PWRs constitute the large majority of the world's nuclear power plants (with notable exceptions being the UK, Japan and Canada). In a PWR, the primary coolant (water) is pumped under high pressure to the reactor core where it is heated by the energy released by the fission of atoms. The heated, high pressure water then flows to a steam generator, where it transfers its thermal energy to lower pressure water of a secondary system where steam is generated. The steam then drives turbines, which spin an electric generator. In contrast to a boiling water reactor (BWR), pressure in the primary coolant loop prevents the water from boiling within the reactor. All light-water reactors use ordinary water as both coolant and neutron moderator. Most use anywhere from two to four vertically mounted steam generators; VVER reactors use horizontal steam generators. PWRs were originally designed to serve as nuclear marine ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pressurizer2
A pressure tank or pressurizer is used in a piping system to maintain a desired pressure. Applications include buffering water pressure in homes. A simple well water control system Referring to the figure on the left, a submersible water pump is installed in a well. The pressure switch turns the water pump on when it senses a pressure that is less than ''Plo'' and turns it off when it senses a pressure greater than ''Phi''. While the pump is on, the pressure tank fills up. The pressure tank is then depleted as it supplies water in the specified pressure range to prevent "short-cycling", in which the pump tries to establish the proper pressure by rapidly cycling between ''Plo'' and ''Phi''. A simple pressure tank would be just a tank which held water with an air space above the water which would compress as more water entered the tank. Modern systems isolate the water from the pressurized air using a flexible rubber or plastic diaphragm or bladder, because otherwise the air ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sump
A sump is a low space that collects often undesirable liquids such as water or chemicals. A sump can also be an infiltration basin used to manage surface runoff water and recharge underground aquifers. Sump can also refer to an area in a cave where an underground flow of water exits the cave into the earth. Examples One common example of a sump is the lowest point in a basement, into which flows water that seeps in from outside. If this is a regular problem, a sump pump that moves the water outside of the house may be used. Another example is the oil pan of an engine. The oil is used to lubricate the engine's moving parts and it pools in a reservoir known as its sump, at the bottom of the engine. Use of a sump requires the engine to be mounted slightly higher to make space for it. Often though, oil in the sump can slosh during hard cornering, starving the oil pump. For these reasons, racing motorcycles and piston aircraft engines are "dry sumped" using scavenge pumps and a s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Rupture Disc
A rupture disk, also known as a pressure safety disc, burst disc, bursting disc, or burst diaphragm, is a non-reclosing pressure relief safety device that, in most uses, protects a pressure vessel, equipment or system from overpressurization or potentially damaging vacuum conditions. A rupture disk is a type of sacrificial part because it has a one-time-use membrane that fails at a predetermined differential pressure, either positive or vacuum. The membrane is usually made out of metal, but nearly any material (or different materials in layers) can be used to suit a particular application. Rupture disks provide instant response (within milliseconds or microseconds in very small sizes) to an increase or decrease in system pressure, but once the disk has ruptured it will not reseal. Major advantages of the application of rupture disks compared to using pressure relief valves include leak-tightness, cost, response time, size constraints, and ease of maintenance. Rupture disks a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pilot-operated Relief Valve
Like other pressure relief valves (PRV), pilot-operated relief valves (PORV) are used for emergency relief during overpressure events (e.g., a tank gets too hot and the expanding fluid increases the pressure to dangerous levels). PORV are also called pilot-operated safety valve (POSV), pilot-operated pressure relief valve (POPRV), or pilot-operated safety relief valve (POSRV), depending on the manufacturer and the application. Technically POPRV is the most generic term, but PORV is often used generically (as in this article) even though it should refer to valves in liquid service. In conventional PRVs, the valve is normally held closed by a spring or similar mechanism that presses a disk or piston on a seat, which is forced open if the pressure is greater than the mechanical value of the spring. In the PORV, the valve is held shut by piping a small amount of the fluid to the rear of the sealing disk, with the pressure balanced on either side. A separate actuator on the piping rel ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Water Hammer
Hydraulic shock (colloquial: water hammer; fluid hammer) is a pressure surge or wave caused when a fluid in motion, usually a liquid but sometimes also a gas is forced to stop or change direction suddenly; a momentum change. This phenomenon commonly occurs when a valve closes suddenly at an end of a pipeline system, and a pressure wave propagates in the pipe. This pressure wave can cause major problems, from noise and vibration to pipe rupture or collapse. It is possible to reduce the effects of the water hammer pulses with accumulators, expansion tanks, surge tanks, blowoff valves, and other features. The effects can be avoided by ensuring that no valves will close too quickly with significant flow, but there are many situations that can cause the effect. Rough calculations can be made using the Zhukovsky (Joukowsky) equation, or more accurate ones using the method of characteristics. History In the 1st century B.C., Marcus Vitruvius Pollio described the effect of water ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Steam
Steam is a substance containing water in the gas phase, and sometimes also an aerosol of liquid water droplets, or air. This may occur due to evaporation or due to boiling, where heat is applied until water reaches the enthalpy of vaporization. Steam that is saturated or superheated is invisible; however, "steam" often refers to wet steam, the visible mist or aerosol of water droplets formed as water vapor condenses. Water increases in volume by 1,700 times at standard temperature and pressure; this change in volume can be converted into mechanical work by steam engines such as reciprocating piston type engines and steam turbines, which are a sub-group of steam engines. Piston type steam engines played a central role in the Industrial Revolution and modern steam turbines are used to generate more than 80% of the world's electricity. If liquid water comes in contact with a very hot surface or depressurizes quickly below its vapor pressure, it can create a steam explosion. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Instrumentation
Instrumentation a collective term for measuring instruments that are used for indicating, measuring and recording physical quantities. The term has its origins in the art and science of scientific instrument-making. Instrumentation can refer to devices as simple as direct-reading thermometers, or as complex as multi-sensor components of industrial control systems. Today, instruments can be found in laboratories, refineries, factories and vehicles, as well as in everyday household use (e.g., smoke detectors and thermostats) History and development The history of instrumentation can be divided into several phases. Pre-industrial Elements of industrial instrumentation have long histories. Scales for comparing weights and simple pointers to indicate position are ancient technologies. Some of the earliest measurements were of time. One of the oldest water clocks was found in the tomb of the ancient Egyptian pharaoh Amenhotep I, buried around 1500 BCE. Improvements were incorpor ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nuclear Reactor Core
A nuclear reactor core is the portion of a nuclear reactor containing the nuclear fuel components where the nuclear reactions take place and the heat is generated. Typically, the fuel will be low-enriched uranium contained in thousands of individual fuel pins. The core also contains structural components, the means to both moderate the neutrons and control the reaction, and the means to transfer the heat from the fuel to where it is required, outside the core. Water-moderated reactors Inside the core of a typical pressurized water reactor or boiling water reactor are fuel rods with a diameter of a large gel-type ink pen, each about 4 m long, which are grouped by the hundreds in bundles called "fuel assemblies". Inside each fuel rod, pellets of uranium, or more commonly uranium oxide, are stacked end to end. Also inside the core are control rods, filled with pellets of substances like boron or hafnium or cadmium that readily capture neutrons. When the control rods are lowe ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Loss-of-coolant Accident
A loss-of-coolant accident (LOCA) is a mode of failure for a nuclear reactor; if not managed effectively, the results of a LOCA could result in reactor core damage. Each nuclear plant's emergency core cooling system (ECCS) exists specifically to deal with a LOCA. Nuclear reactors generate heat internally; to remove this heat and convert it into useful electrical power, a coolant system is used. If this coolant flow is reduced, or lost altogether, the nuclear reactor's emergency shutdown system is designed to stop the fission chain reaction. However, due to radioactive decay, the nuclear fuel will continue to generate a significant amount of heat. The decay heat produced by a reactor shutdown from full power is initially equivalent to about 5 to 6% of the thermal rating of the reactor. If all of the independent cooling trains of the ECCS fail to operate as designed, this heat can increase the fuel temperature to the point of damaging the reactor. *If water is present, i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Temperature
Temperature is a physical quantity that expresses quantitatively the perceptions of hotness and coldness. Temperature is measured with a thermometer. Thermometers are calibrated in various temperature scales that historically have relied on various reference points and thermometric substances for definition. The most common scales are the Celsius scale with the unit symbol °C (formerly called ''centigrade''), the Fahrenheit scale (°F), and the Kelvin scale (K), the latter being used predominantly for scientific purposes. The kelvin is one of the seven base units in the International System of Units (SI). Absolute zero, i.e., zero kelvin or −273.15 °C, is the lowest point in the thermodynamic temperature scale. Experimentally, it can be approached very closely but not actually reached, as recognized in the third law of thermodynamics. It would be impossible to extract energy as heat from a body at that temperature. Temperature is important in all fields of natur ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
