This is a synthetic element and does not occur in nature. It is produced through neutron absorption by fertile U238 and subsequent beta decays. Plutonium melts at 640*C. It is extremely toxic and emits alpha rays. Due to its naturally fissionable , plutonium continues to emit high energy gamma and other radiation. The metal is chemically more reactive than uranium and has a poor resistance to corrosion. It has six allotropic forms. The chief application of plutonium is in the production of atomic weapons and also in breeder reactors. Since some plutonium alloys and compounds emit neutrons, adequate health protection is necessary while using these materials.
Steam Pressure at inlet to a steam turbine is reduced by throttling process to maintain the speed of the turbine constant at part load and hence this method of governing is called "Throttle Governing". Construction : Throttle governing system consists of a centrifugal governor, a lever , an oil pump , a pilot piston , control valve , a relay piston and a throttle valve. The throttle valve is moved by a relay piston. The relay piston is actuated by pilot piston control valve. There are two piston valves covering ports in the pilot piston control valve without any overlap. These piston valves are operated by lubricating oil supplied by a gear pump at 2 to 4 bar. The oil returns to the drain from this chamber. Working : When the turbine works on full rated load, the throttle valve will remain open. When the load is decreased, the energy output of the turbine becomes in excess and the turbine shaft speed increases. Hence, governor sleeve will lift. The upward movement of the
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