Abstract: A method and apparatus for measuring radioactivity associated with nuclear reactor coolant leaks. The method includes providing a delay tank in a gas sampling line upstream of a radiation particulate monitor, the delay tank allowing radioactive noble gases from the leak to decay to radioactive daughter particulates that are monitored by the radiation particulate monitor. The apparatus includes the delay tank as well as a background delay tank and a valve sequencer for comparing radiation associated with the delay tank to radiation associated with the background delay tank.

Abstract: An apparatus for monitoring the pressure within a cask containing radioactive materials is disclosed. The apparatus comprises a differential pressure sensor sealingly connected to a bore that penetrates through the wall of the cask for directly monitoring the pressure of the helium gas contained within the cask and for providing a first barrier between the helium gas and the ambient atmosphere. An evacuated sensor chamber surrounds both the outlet end of the through-wall bore and the differential pressure sensor for providing a second barrier between the helium and the ambient atmosphere as well as a vacuum reference point for the differential pressure sensor. An absolute pressure sensor is connected in parallel to the through-wall bore to allow the system operator to determine whether or not a reduction in the pressure sensed by the differential pressure sensor is the result of a leakage condition in the cask, or in the evacuated sensor chamber.

Abstract: A method and device for monitoring the power output of a nuclear reactor in the low power range, by detecting neutrons produced by the reactor and producing a representation of the number of neutrons detected during each of a succession of equal measuring intervals; and producing a power output level indication having a value associated with each measuring interval by a digital operation in which the indication value associated with a preceding time interval is altered according to a function of the representation produced during the detecting step for the present measuring interval.

Abstract: In a method and apparatus for reducing the effects of frequency burst noise and noise spikes accompanying a random pulse signal, pulses with an amplitude above a high threshold or below a low threshold are eliminated, with the remaining pulses of intermediate amplitude being statistically filtered. The statistical filter compares the current pulse count rate signal to maximum and minimum statistical limits generated from the recent average value of the pulse count rate using Poisson statistics, and clamps the output to the limit which is exceeded. If the pulse count rate is between the statistical limits, it is used as the output pulse count rate signal. If the statistical limits are exceeded for a designated interval indicative of a true change in the pulse count rate, clamping of the output signal is overridden so that the true change in pulse count rate can be tracked. Statistical filtering is resumed when the current pulse count rate is again within the statistical limits.

Abstract: A system which measures direct current drift and noise in sensor signals from redundant sensors utilizing a parity-space algorithm. Parity vector signals produced by the parity-space algorithm are averaged to provide a direct current (DC) drift signal. An instantaneous noise signal is found by subtracting the direct current drift signal from a parity vector signal for one of the samples of the sensor signals. The RMS value of the instantaneous noise signals are averaged to provide sensors noise signals.

Abstract: Numerous signal conditioning circuits on a plurality of printed circuit boards are calibrated remotely by a signal processing unit which sends coded signals to each board, either sequentially or in parallel, to connect either on-board or off-board test signals to one of the conditioning circuits in place of its field generated input. The processing unit utilizes the actual and expected responses of each conditioning circuit to low and high test signals to generate a gain and an offset which are applied to the conditioned field signal to provide a calibrated signal. The time constant for each conditioning circuit is also measured periodically, or upon a selected temperature change, for use in generating a minimum waiting period for obtaining valid data following transfers between the field generated signals and the test signals.

Abstract: An improved nuclear reactor primary loop flowmeter having two spaced N-16 detectors (12 and 14) positioned along the primary loop piping for monitoring the N-16 activity within the coolant at the respective detector locations. The outputs of the two detectors are cross-correlated to determine the transit time of corresponding N-16 perturbations viewed at the two detector locations. The improvement comprises means for switching (34 and 36) the respective detector output electronic processing channels (18 and 20) between detectors (12 and 14) and measuring the maximum cross-correlation function (30 and 32) with the detector output channels in their original and switched positions to determine the true coolant transit time between detector locations and any phase shift induced by the detector output channels.

Abstract: A method and apparatus for establishing the axial flux distribution of a reactor core from monitored responses obtained exterior of the reactor. The monitored responses obtained exterior of the reactor. The monitored responses are obtained from at least three axially spaced flux responsive detectors that are positioned within proximity of the periphery of the reactor core. The detectors provide corresponding electrical outputs representative of the flux monitored. The axial height of the core is figuratively divided at a plurality of space coordinates sufficient to provide reconstruction in point representation of the relative flux shape along the core axis. The relative value of flux at each of the spaced coordinates is then established from a sum of the electrical outputs of the detectors, respectively, algebraically modified by a corresponding preestablished constant.