Year
1989
Abstract
A multi-input system using standard commercially available Nal(Tl) detectors, electronics, and an MCA was developed to improve nuclear safety in the plutonium processing facility of the Savannah River Plant. Detectors are positioned to nonintrusively measure gamma-ray spectra of a number of process tanks continuously. Based on an MCA analysis of the 330-420 keV complex from Pu-239, an analog signal, proportional to the plutonium concentration, is sent to a strip-chart recorder for tracking, alarm functions, and interlocking of certain process equipment. A computer is used to scale all measurements to user-defined limits, and to perform continuous diagnostic checks to ensure proper calibration and performance of each monitor. In place, but normally not used, are an SCA and ratemeter for each detector, so that in the event of an MCA or computer failure, monitoring functions can be maintained. The system was designed with expansion in mind and has had additional monitors added three times during its four years of very reliable operation.