Improvement and optimization of master/bypass valve switching process for steam generator level control of nuclear power plant

According to the statistics of domestic nuclear power plant CPR1000 units, the common failure modes in the steam generator level control about the master/bypass valve switching process were described. The main modes include that the master/bypass valve switching threshold owes excellent, the master/bypass valve frequently switches and the master valve opens too late. And then a solution was raised about how to improve the master/bypass valve switching process, including switching point optimization, disturbance value control and difference control. This solution is performed in the project site and is verified feasible and effective. (authors)