Patent Number: 054224926
Section: summary

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates, in general, to the monitoring of the criticality of nuclear fuel in fuel manufacturing or handling facilities, and in particular, to a new and useful device for calibrating a criticality detector. 2. Description of Related Art In nuclear fuel manufacturing plants, criticality monitors and detectors are used to monitor the criticality of the nuclear fuel. To ensure correct operation, these systems have to be calibrated periodically in order to maintain proper adjustments to the electronics of the system. Presently, the calibration procedures for these criticality monitors are conducted by hand. This procedure includes having an operator attach a radiation source to a hand-held rod near the criticality detector and measure the distance from the detector to the radiation source with a tape measure. In performing this calibration procedure by hand, the operator is usually required to stand on a ladder in order to remove the criticality detector or hold the radiation source for measuring. Not only is this procedure not very accurate for calibration purposes, but it is also hazardous to the operator due to the exposure to the radiation source, and his position on the ladder. Presently, there is no known device for calibrating a criticality detector which is accurate, safe to a user and cost efficient. SUMMARY OF THE INVENTION The present invention pertains to a calibrating device for a criticality monitoring system for a nuclear fuel manufacturing plant which allows for a more accurate, safe and cost-effective method of calibrating a criticality detector over known methods. The present invention comprises a radiation protective holder for containing a radiation source which aligns the radiation source with the criticality detector. A measuring rod having a plurality of graduations or calibrations is aligned parallel with the axis of the holder. A nylon guide is connected to the holder and movably connected to the measuring rod for moving the holder and the radiation source along the axis for detection by the criticality detector. The nylon guide is aligned in the same horizontal plane as the radiation source for indicating a calibration measurement. It is an object of the present invention to provide a calibration device for a criticality monitoring system for a nuclear fuel manufacturing plant which is accurate, safe to a user and cost-effective. The various features of novelty which characterize the invention are pointed out with particularity in the claims annexed to and forming a part of this disclosure. For a better understanding of the invention, its operating advantages and specific objects attained by its uses, reference is made to the accompanying drawings and descriptive matter in which a preferred embodiment of the invention is illustrated.