The plant one eight special requirements of the road of pneumatic valve

as a result of the primary circuit medium, technical parameter, environmental conditions, safety and reliability requirements for pneumatic valves are different in the conventional power station, so in addition to general requirements, there are special requirements:
) Anti irradiation for
the plant to the pneumatic valve irradiation dose for. X GY, pneumatic control valve selection of materials in addition to meet the working medium, should also be resistant to radiation, namely material irradiated after its use performance does not change. No activation, namely material shorter half-life. Half-life long materials such as copper, cobalt, etc. Use less as far as possible, don't even need. Foreign preparation with nickel base alloy, at present our country is ready for use.
） Containment requirements
as a result of the medium is radioactive water containing boron, requirement of pneumatic control valve sealing, no leakage, the flange seal should be safe and reliable, to ensure that the pneumatic valve stem without leakage, structure should be adopted on the bellows and intermediate cause leakage. To facilitate the cleaning requirements of pneumatic valves inside and outside the surface roughness of the surface have certain, pneumatic valve body should avoid blind Angle, to prevent the deposition of radioactive particles.
） Packing and gasket requirements
as a result of the primary circuit water quality requirements, the requirements of stainless steel equipment. Especially thin wall equipment such as fuel element cladding, evaporating pipe, corrugated pipe, due to the chloride ion water quality will be broken, caused the corrosion of the stainless steel equipment, so the requirement of pneumatic valve selection of packing, gasket, chloride ion content should be less than the PPM. And do not contain halogen.
） Disable material
the result of the accident of the containment vessel safety spray liquid of Na ( OH and boron, pneumatic control valve generally aluminum and zinc or zinc is strictly prohibited, if you want to use must obtain the consent of the overall design. Pneumatic valves shall not choose low melting point materials such as tin, lead, etc. , in contact with the medium and surface electroplating and nitride.
） LOCA requirement
in containment vessel pneumatic valves shall meet the requirements of LOCA, namely under loss of coolant accident condition of pneumatic valve can still moves, which requires the pneumatic valve selection of electric equipment, instruments, meters and other attachments, shall be passed the test of the LOCA.
） Structure for
the pneumatic valve medium radioactive environment has certain irradiation dose, and therefore require dismantling and maintenance of pneumatic valve is faster, so the requirement of pneumatic valve has simple structure, easy installation and maintenance etc.
pneumatic valve flow design should be smooth, as far as possible to reduce or avoid blind Angle. Smooth surface smooth, easy to clean, rinse.
） The requirement of safe and reliable
in the operation of the pneumatic valves in nuclear power plants, plays a very important role, pneumatic valve performance is good or bad, will directly affect the safety of nuclear power plant, so the plant requires the performance of the pneumatic valve must be safe and reliable. In order to achieve this goal, request factory before a formal offer for nuclear power products, must choose the typical representative of pneumatic valves for prototype. The prototype must undergo a series of type tests. Such as cold performance test, hot state simulation condition test, life test, seismic experiment, electrical equipment should also be LOCA test, etc. , to verify the safety and reliability of the pneumatic valve performance.
） Seismic demands
nuclear power plant nuclear grade pneumatic valves in power station during the earthquake or after the earthquake, pneumatic valve pneumatic valve structure and can continue to keep the integrity of the pressure boundary, and good performance.