Standard Practice for Performance Evaluation of In-Plant Walk-Through Metal Detectors
|Publication Date:||10 December 1997|
|ICS Code (Alarm and warning systems):||13.320|
|ICS Code (Nuclear power plants. Safety):||27.120.20|
This practice is one of several (see Appendix X1) developed to assist operators of nuclear facilities with meeting the metal detection performance requirements set by regulatory authorities.
This practice consists of four procedures useful for evaluating the in-plant performance of walk-through metal detectors (see Fig. 1).
Two of the procedures provide data for evaluating probability of detection. These procedures use binomial data (alarm/not alarm).
The detection sensitivity test (DST; see Note 1) is the initial procedure in the detection probability evaluation series. It is used to establish the probability of detection immediately after the detector has been adjusted to its operational sensitivity setting.
NOTE 1-The DST is one of two procedures used to evaluate detection rate. The Detection Sensitivity Verification Test (DSVT) is the other. In the evaluation test strategy, the DST is used to initially determine and document the detection rate and then the DSVT is used to periodically check that the detection rate continues to meet the requirements.
The detection sensitivity verification test (DSVT; see Note 1) procedure periodically provides data for evaluation of continuing detection performance.
The third procedure is a "functional test." It is used routinely to verify that a metal detector is operating and responds with the correct audio and visual signals when subjected to a condition that should cause an alarm.
The fourth procedure is used to verify that alarms generated during detection sensitivity testing were likely the result of the detection of metal and not caused by outside interferences or the perturbation of the detection field by the tester's body mass.
This procedure also can be used to establish a probability of occurrence for false alarms, for example, 20 test passes by a clean-tester resulting in no alarms indicates a false alarm probability of less than 0.15 at 95 % confidence. This procedure is optional unless required by the regulatory authority.
This practice does not set test object specifications. The specifications should be issued by the regulatory authority.
This practice is intended neither to set performance levels nor to limit or constrain technologies.
This practice does not address safety or operational issues associated with the use of walk-through metal detectors.
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.