Analytic Redundancy for On-Line Fault Diagnosis in a Nuclear Reactor

A computer-aided diagnostic technique has been applied to on-line signal validation in an operating nuclear reactor. To avoid installation of additional redundant sensors for the sole purpose of fault isolation, a real-time model of nuclear instrumentation and the thermal-hydraulic process in the primary coolant loop was developed and experimentally validated. The model provides analytically redundant information sufficient for isolation of failed sensors as well as for detection of abnormal plant operation and component malfunctioning. Nomenclature B =bias for sensor calibration b = error bound for measurement C = specific heat F = mass flow rate of primary coolant H = measurement matrix K = product of heat transfer coefficient and area £ = number of measurements M = thermal mass m = measurement p = parity vector Q = power or rate of energy flow S = scale factor for measurement T = temperature t = time V = projection matrix v = sensor output in volts w = weighting coefficient (0 < w < 1) x = true value of a measured variable e = measurement noise 77 = parameter associated with heat transfer £ = shim blade position r = time constant X = fraction of neutron power