Study on the optimization of controller time constant for OTDT/OPDT rector trip system at nuclear power plant

The result s of measurements showed that the reactor temperature fluctuation was higher after RTD modification than that of original system. So partial turbine runback signal and temperature deviation between three channel is occurred. This paper suggests that time constant of lag unit be increased to reduce the temperature fluctuation. Nevertheless we can meet the time limit of total time delay including RTD time response, and trip circuit channel electronics delay, 8 sec. The electronic delay is the trip circuit channel electronics delay plus the time for the reactor trip breakers to open and time for the CRDM stationary grippers to disengage(gripper release time). Time constants utilized in the lag compensator for ΔT changed from 0 sec to 2 secs . Time constant utilized in the measured Tavg lag Compensator is changed from to 0 sec to 2 secs. In this case we could abtain lower fluctuation and could meet the response time limit