Estimating minimum detectable concentrations achievable while scanning building surfaces and land areas.

Abstract

Scanning is performed during radiological surveys to identify elevated levels of direct radiation. The levels detected depend on the surveyor's abilities and decision processes. A method is described for anticipating levels that surveyors might reasonably be expected to detect in scanning by estimating the increment in a survey instrument's counting rate that would be necessary to support specified limits on Type I and Type II error rates, taking into account the fact that human beings typically do not operate with perfect efficiency. The result is applied to calculations of minimum detectable concentrations (MDCs) achievable while scanning structure surfaces and land areas. The approaches used for determining scan MDCs are provided, along with examples for common radionuclide contaminants and field survey instrumentation.