Adjustment Calculation of the Limit Orifice Plate for Low Pressure Safety Injection Test of Nuclear Power Plant

When an accident happened at the reactor,the safety injection system should inject cooling water into the reactor to reduce or control the development of the accident.In the daily operation and maintenance of nuclear power plant, low pressure safety injection test needs to be performed in order to verify whether the flow rate of the cooling water meets the design requirement at different conditions.In case the design requirement is not met,adjustment should be made to the aperture of the orifice plate on the corresponding pipeline of the low pressure safety injection system.Through the analysis of the limiting orifice plate and pipeline characteristics of the complex pipeline,the calculation method of the adjustment of the aperture of the limiting orifice associated with the low pressure safety injection test.Through the example of a nuclear power plant orifice plate adjustment verification, the actual deviation of the theoretical calculation of the orifice plate aperture and the actual one is less than l%.Practice shows that the calculation method of the orifice diameter adjustment of the current limiting orifice can meet the engineering requirements.