Patent ID: 7596198

Claim:
A method for recovering operating margin in a nuclear reactor, the nuclear reactor including a steam generator, a Reactor Coolant System having a hot leg with a temperature, T hot , and a cold leg with a temperature, T cold , a Reactor Trip System having an Over Temperature Delta Temperature trip function and an Over Power Delta Temperature trip function, and a control system, the method comprising: measuring a temperature in the hot leg of the Reactor Coolant System and providing a hot leg temperature signal representative thereof; filtering the hot leg temperature signal to smooth signal perturbations resulting from temperature fluctuations; measuring a temperature in the cold leg of the Reactor Coolant System and providing an unfiltered cold leg temperature signal representative thereof; establishing an Over Temperature Delta Temperature setpoint for the Reactor Trip System from the filtered hot leg temperature signal and the unfiltered cold leg temperature signal; establishing an Over Power Delta Temperature setpoint for the Reactor Trip System from the filtered hot leg temperature signal and the unfiltered cold leg temperature signal; measuring the difference between the filtered hot leg temperature signal and the unfiltered cold leg temperature signal; comparing the measured difference between the filtered hot leg temperature signal and the unfiltered cold leg temperature signal to said Over Temperature Delta Temperature setpoint; comparing the measured difference between the filtered hot leg temperature signal and the unfiltered cold leg temperature signal to said Over Power Delta Temperature setpoint; and tripping the nuclear reactor when the measured difference between the filtered hot leg temperature signal and the unfiltered cold leg temperature signal exceeds the Over Temperature Delta Temperature setpoint or the Over Power Delta Temperature setpoint.