Significance and Use 5.1 SNM monitors are an effective means to search pedestrians for concealed SNM. Maintaining monitor effectiveness rests on appropriate calibration and adjustment being part of a continuing maintenance program. 5.2 The significance of this guide for monitor users who must detect SNM is to describe calibration and adjustment procedures for the purpose. 5.3 The significance of this guide for monitor manufacturers is to describe calibration procedures, particularly for detecting forms of SNM that may not be readily available to them.Scope 1.1 This guide covers calibrating the energy response of the radiation detectors and setting the discriminator and alarm thresholds used in automatic pedestrian special nuclear material (SNM) monitors. 1.2 Automatic pedestrian SNM Monitors and their application are described in Guide C1112, which suggests that the monitors be calibrated and tested when installed and that, thereafter, the calibration should be checked and the monitor tested with SNM at three-month intervals. 1.3 Dependable operation of SNM monitors rests, in part, on an effective program to test, calibrate, and maintain them. The procedures and methods described in this guide may help both to achieve dependable operation and obtain timely warning of misoperation. 1.4 This guide can be used in conjunction with other ASTM standards. Fig. 1 illustrates the relationship between calibration and other procedures described in standard guides, and it also shows how the guides relate to an SNM monitor user. The guides below the user in the figure deal with routine procedures for operational monitors. Note that Guide C993 is an in-plant performance evaluation that is used to verify acceptable detection of SNM after a monitor is calibrated. The guides shown above the user in Fig. 1 give information on applying SNM monitors (C1112) and on evaluating SNM monitors (C1169) to provide comparative information on monitor performance. FIG. 1 The Relationship of Calibration to Other Procedures Described in Standard Guides for SNM Monitors 1.5 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
