Evaluation of Lead Detectors. Interim Evaluation of Princeton Gamma Tech XK-3 Prototype X-Ray Fluorescent Lead Detectors

摘要

Results are reported from an interim evaluation by the National Bureau of Standards of the performance of portable x - ray fluorescent lead detectors recently developed by Princeton Gamma Tech, Incorporated, for HUD. Minimum and optimum performance levels are reported for sensitivity, accuracy, precision, adaptability, and safety. The XK prototypes exhibited no significant radiation emission or radioactive contamination when exposed to the Radiation Survey Meter Test and the Radiation Smear Test. The prototype consistently gave a positive indication of the presence of lead at a level of 1.0 milligrams per square centimeter on a variety of substrates such as wood, gypsum board, Mylar, and steel, thus conforming to the minimum sensitivity required by the contract. The XK - 3 did not show extreme trends when measurements were repeated for a variety of substrates. The minimum performance requirement for adaptability is that lead detectors must be capable of detecting 80 percent of the total lead present in a coating containing 20 layers of paint. The instrument failed to detect 80 percent of the lead in the 4 - layer material 3 out of 10 times; in the 8 - layer material, 1 out of 10 measurements; but in the 15 - layer and 20 - layer samples, successfully detected at least 80 percent of the lead in all cases. In no case did the instrument meet the stated requirements for accuracy in the range 0.5 to 2.5 milligrams per square centimeter. Tabular data are provided.