DETECTION LIMITS OF A LABORATORY PULSED GAMMA-NEUTRON-ACTIVATION ANALYSIS SYSTEM FOR THE NONDESTRUCTIVE ASSAY OF MERCURY, CADMIUM, AND LEAD

Detection of Hg, Cd, and Pb within concrete matrices located in 8-gal drums was successfully demonstrated using a pulsed gamma neutron activ ation analysis system. Real-time assays of 600 s led to the detection of these metals at concentration levels ranging, in parts per million (ppm) by weight, from 487 to 19 820 for Hg, 485 to 8181 for Cd, and 99 27 to 19 950 for Pb. The measurements of Hg and Cd relied on the obser vation of thermal neutron-induced prompt gamma rays, whereas the Pb me asurements relied on the observation of decay gamma rays from Pb-207m, a product of fast neutron-induced reactions in Pb. The projected bowe r limits of detection of the current system for a 600-s run are 15, 17 0, and 8600 ppm for Cd Hg, and Pb, respectively. Up to a one-order mag nitude of improvement in sensitivity is anticipated through the enhanc ement of the system's detector and neutron source. The results obtaine d confirm the potential of prompt and decay gamma neutron activation a nalysis as an effective method for the nondestructive analysis of haza rdous metals in mixed-waste drums.