Nuclear power pneumatic valve design, materials, test technology 1

in the test and inspection has made the detailed description, American ASME standards such as JEM in Japan. And provide the evaluation standard.
because of its special and complex and bad working condition, nuclear power pneumatic valves. Combined with the enormous quantity wide, so the demand is higher.

nuclear power pneumatic valve working conditions:
the medium temperature, pressure and radioactive level of rigour is also very special nuclear power pneumatic valves in addition to the complicated working condition of the environment.

nuclear power transmission medium pneumatic valve are mainly: saturated steam and condensate, radioactive steam heavy water, corrosive, radioactive irradiation, dilute sulphuric acid and alkali medium, carbon dioxide, sodium, helium, oil, vacuum and other fluid medium.

but it is much more complicated nuclear power plant operating conditions. The liquid metal cooling agent fast reactor device, once the drift diameter pneumatic valve working conditions on the road is the most complex on the nuclear power plant at the present stage of steam parameters than the thermal power plant steam parameters ( Pressure. MPa ℃ temperature) Lower. As the highest (steam parameters The temperature of the steam turbine before for ℃, the pressure is zero. Nuclear power pneumatic valve rare fault type
the most common type of fault has the following four: nuclear power plant operation of pneumatic valves in the system. Nuclear power pneumatic valve technical requirements
nuclear power pneumatic valve its technical characteristic and the request is higher than coal-fired power pneumatic valve. The technical requirements of nuclear power pneumatic valve besides convention pneumatic valve technical requirements, according to the actual working condition of the nuclear power pneumatic valve operation. Medium also considered impurities pollution, environment temperature, operating temperature, environment humidity, radioactive, dc power supply and voltage fluctuation, the earthquake and vibration stability under the condition of technical requirements, safe level and so on.


1) nuclear power pneumatic valve data nuclear power pneumatic valve materials must have good corrosion resistance, radiation resistance, impact resistance and resistance to intergranular corrosion. In general:
required the ASMEBPVC - a pressure on the parts Ⅱ- D - The data requirements in table A and table B
B pneumatic valve stem and bearing bolt precipitation hardened steel is often used to manufacture the
c packing use graphite fiber, pure asbestos or expanded graphite

(2) nuclear power pneumatic valve actuator
must have reliability, safe operation of nuclear power quality and performance of the pneumatic valve actuator is very important and key. At the same time, should be able to withstand the temperature, pressure, humidity, irradiation, earthquake damage, a maximum chemical pollution and the change of the power supply source, and necessary in the event of a water loss fault conditions, can still work within the prescribed time limit, General specification for the day)
in addition to drive electric parts requirements with O ring sealing isolation with the outside environments, in addition. Drive the working condition of nuclear power should also be taken into account by its designer with high-pressure pneumatic valve fast operational problems ( Under the general specification, CL of pneumatic valve, American standard its fast operation for seconds)

(3) the design of nuclear power pneumatic valve
a strength design

strength calculation is indispensable in addition to the strength of the conventional calculation, finite element analysis and seismic analysis, nuclear power in the design of pneumatic valve. Pneumatic valves for nuclear safety level, also asked for: the limit of a thin film stress calculation, a thin film stress + the limits of the bending stress calculation, and loop rev - Stop cycle variations in the primary and secondary stress of about the limit of the calculation, in addition to the loop rev - Stop working outside of the primary and secondary stress change of amplitude limit calculation and fatigue analysis.

structure design b

don't allow any leakage, because most of the radioactive nuclear power system transmission medium. So the structural design of packing, corrugated pipe, pneumatic pneumatic valve seat seal structure design is particularly important, The shape of the pneumatic valve body design, rules in ASME specification)
packing usually use multiple seal structure, Ω ring seal structure and packing layer sandwiched between saucer reed of the stuffing box seal structure. Corrugated tube combined bellows seal structure in general. For important high pressure pneumatic valve, abroad. Pneumatic valve seat structure of forging. In addition, pneumatic valve and pipeline connection with butt-joint or socket welding structure.

(4) the test and inspection of nuclear power pneumatic valve
the hydrostatic test of a nuclear power pneumatic valves require regular - On shell test, pneumatic valve strength test, seal test, pneumatic seat sealing test, packing seal test;
such as electric pneumatic valve, pneumatic shock test pneumatic valve; B with actuators.
c of pneumatic valve and static pressure in all forms of operation life test;
d important pneumatic valve is necessary in primary circuit after cold, hot and LOCA accidents ( The loss of coolant accident) The test.