Nuclear power plant isolation valve control circuit

Abstract

The invention discloses a nuclear power plant isolation valve control circuit, which comprises a safety module, an operation closing module, an operation opening module, a limit switch module and a control module, and is characterized in that the control module is used for selectively outputting a valve opening and closing signal according to a safety signal, an operation closing signal, an operation opening signal and a limit switch signal, the control module comprises a first AND gate, a first OR gate, an RS trigger, a second OR gate and a second AND gate, the output end of a reactor closing unit is negated, and isconnected with the input end of the second AND gate, the output end of a shutdown disc closing unit is negated, and is connected with the input end of the second AND gate, the output end of the second OR gate is connected with the input end of the second AND gate, and the output end of the second AND gate outputs a valve switching signal. According to the invention, the nuclear power plant isolation valve control circuit can avoid automatic closing of the valve under the false triggering conditions such as false touch, short circuit, rust corrosion and the like, and avoid pile and machine jumping; and on the basis of not changing the original function and not improving the rejection rate, the defects of the original design are effectively overcome, and the maloperation rate is reduced.

Description

technical field [0001] The invention relates to the field of nuclear power, in particular to a control circuit for an isolation valve of a nuclear power plant. Background technique [0002] The CPR1000 nuclear power unit has 3 evaporators, and the secondary circuit corresponding to each evaporator is equipped with 1 main steam isolation valve and 1 main feed water isolation valve. When the reactor coolant system and steam generators are full of mass and energy, the isolation function of the main steam isolation valve and the main feed water isolation valve can ensure that in the event of a high energy pipe rupture, a single failure will not cause more than one steam generator vent to maintain reactor coolant and containment pressure within acceptable limits. At the same time, as a natural extension of the containment, it also acts as a third barrier to prevent the release of extra mass and energy. [0003] The control strategy of the main steam isolation valve (hereinafter...

AI Technical Summary

Problems solved by technology

[0011]Question 1: The valve is in the fully open position during the power operation of the unit. If the SM5 signal is triggered by mistake (mistouch, short circuit, rust, etc.), the valve will automatically close. As a result, heap jumping and machine jumping (occurred 5 times on site for CPR1000 stacking units)

[0012]Question 2: After using the ECP disk TO to close the valve during shutdown, if the SM5 signal does not trigger (swing arm stuck, feedback link bracket displacement, etc.), when TO resets Afterwards, the valve will open again unexpectedly, and the parameters of the primary circuit of the reactor will fluctuate greatly (once the CPR1000 reactor unit occurred once)

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