ASTM International

Standard Guide for Laboratory Evaluation of Automatic Pedestrian SNM Monitor Performance
 N C1169

Annotation

The requirement to search pedestrians for special nuclear material (SNM) to prevent its theft has long been a part of both United States Department of Energy and United States Nuclear Regulatory Commission rules for the physical protection of SNM. Information on the application of SNM monitors to perform such searches is provided in Guide C1112. This guide establishes a means to compare the performance of different SNM pedestrian monitors operating in a specific laboratory environment.2 The goal is to provide relative information on the capability of monitors to search pedestrians for small quantities of concealed SNM under characterized conditions. The outcome of testing assigns a sensitivity category to a monitor related to its SNM mass-detection probability; the monitor's corresponding nuisance-alarm probability for that sensitivity category is also determined and reported.

The evaluation uses a practical set of worst-case environmental, radiation emission, and radiation response factors so that a monitor's lowest level of performance in a practical operating environment for detecting small quantities of SNM is evaluated. As a result, when that monitor is moved from laboratory to routine operation, its performance will likely improve. This worst-case procedure leads to unclassified evaluation results that understate rather than overstate the performance of a properly used SNM monitor in operational use.

The evaluation applies to two types of SNM monitors that are used to detect small quantities of SNM. Both are automatic monitors; one monitors pedestrians as they walk through a portal formed by the monitor's radiation detectors (walkthrough or portal monitor), and the other monitors pedestrians who are stationary for a short period of time while they are monitored (wait-in monitor). The latter can be a portal monitor with a delay mechanism to halt a pedestrian for a few seconds or it can be an access-control booth or room that contains radiation detectors to monitor a pedestrian waiting for clearance to pass.