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A blowdown valve (BDV) is a type of shutdown valve designed to depressurize a pressure vessel by directing vapour to a flare, vent or blowdown stack in an emergency. BDVs fail-safe to the open position upon failure of the control system. [1] The type of valve, type of actuation and performance measurement are similar to an ESD valve.
ESD level 3: provides fluid containment by closing shutdown isolation valves or emergency shutdown valves (ESDVs). The safety shutdown system shall shut down the facilities to a safe state in case of an emergency situation, thus protecting personnel, the environment and the asset. The safety shutdown system shall manage all inputs and outputs ...
Valves are actuated by an electric motor, hydraulic fluid or air. For air-operated control valves, electrical signals from the control system are converted to an air pressure for the valve actuator in a current/pneumatic I/P converter. Upon loss of pneumatic or hydraulic pressure valves may fail to an open (FO) or fail to a closed (FC) position.
Electronic control systems use a configurable electronic module that connects between the supply from the ESD system and the solenoid valve. In order to perform a test the timer de-energises the solenoid valve to simulate a shutdown and re-energises the solenoid when the required degree of partial stroke is reached.
SCRAM button at the Experimental Breeder Reactor I in Idaho. Sometimes the switch will have a flip cover to prevent inadvertent operation. A scram or SCRAM is an emergency shutdown of a nuclear reactor effected by immediately terminating the fission reaction.
SCSSV – surface-controlled subsurface safety valve; SDON – shut down overnight; SEP – surface emissive power; SPCU – subsea control unit; SCVF – surface casing vent flow. It's kind of test [citation needed] SD – sonic density; SDFD – shut down for day; SDFN – shut down for night; SDIC – sonic dual induction; SDL – supplier ...
When hydraulic pressure is applied down a control line, the hydraulic pressure forces a sleeve within the valve to slide downwards. This movement compresses a large spring and pushes the flapper downwards to open the valve. When hydraulic pressure is removed, the spring pushes the sleeve back up and causes the flapper to shut.
The Reactor Protection System (RPS) is a system, computerized in later BWR models, that is designed to automatically, rapidly, and completely shut down and make safe the Nuclear Steam Supply System (NSSS – the reactor pressure vessel, pumps, and water/steam piping within the containment) if some event occurs that could result in the reactor entering an unsafe operating condition.
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