Abstract: A plurality of neutron flux sensors (44,46,48,50) and a corresponding plurality of gamma flux sensors (62,64,66,68) are distributed throughout axial zones (24,26,28,30) of the core (14) at the same or closely proximate locations. A steady state comparison, or bias, between the signals of a given neutron/gamma sensor pair are monitored (314, 316), and a divergence (or convergence) can readily be detected through simple signal filtering, to detect a shift in the bias. The pattern of significant convergence and divergence throughout the core, is indicative of the thermal hydraulic stability of the core.

Abstract: An apparatus for monitoring the position of the shaft of a coolant circulating pump of a nuclear steam generating system comprising light source for directing a light beam at a number of reflecting surfaces on the shaft and a pair of spaced apart light receiving devices adapted to receive light beams reflected off the reflecting surface. Light from the receiving devices is conveyed, by fiber optic cables, to intensity measuring devices which measure the intensity of the two light beams on a time-dependent basis. A processor calculates the shaft rotational speed and the magnitude of the shaft wobble as functions of the time-dependent intensity measurements of the pair of reflected light beams.

Abstract: Apparatus for making a transition from leads (12-26) of a temperature measuring thermocouple to extension wires (44-58) within a hermetically sealed cable sheath (60) of small diameter. The interior of the cable sheath (60) is shielded from electromagnetic radiation by an electrically conductive liner (62). A thermally conductive, electrically insulating material (66) surrounds the intermediate junctions (28-42). The temperature of the intermediate junctions (28-42) is measured (64) providing a signal to compensate the voltage generated by the temperature measuring thermocouples due to the thermoelectric effect of the intermediate junctions (28-42).