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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.
Apart from the actuation of shutdown valves and blowdown valves, outputs include isolation of electrical sources, power shutdown, activation of fire pumps, etc. ESD is usually activated when a loss of containment and/or a fire is detected, although it may be activated at any time the plant operators feel it is necessary to preserve life, assets ...
Emergency core cooling systems (ECCS) are designed to safely shut down a nuclear reactor during accident conditions. The ECCS allows the plant to respond to a variety of accident conditions (e.g. LOCAs) and additionally introduce redundancy so that the plant can be shut down even with one or more subsystem failures. In most plants, ECCS is ...
The basic principle behind partial stroke testing is that the valve is moved to a predetermined position in order to determine the performance of the shut down valve. This led to the adaptation of pneumatic positioners used on flow control valve for use in partial stroke testing. These systems are often suitable for use on shutdown valves up to ...
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.
The solver will decide based on 2-out-of-3 voting whether or not to activate the final element. the 1oo2 solenoid panel decides which valve to be closed. The final elements consist here of two block valves that stop flow to the downstream facilities (right) to prevent them from exceeding a maximum pressure.
Gisele Pelicot, whose husband Dominique Pelicot and 50 other men are on trial for raping her, gave her final courtroom statement in the shocking case.
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.