IEC 62484-2020 Radiation protection instrumentation – Spectrometric radiation portal monitors (SRPMs) used for the detection and identification of illicit trafficking of radioactive material.
4 Design requirements
4.1 General
4.1.1 Overview
The equipment addressed by this document shall detect the presence of gamma-ray emitting sources, identify gamma-emitting radionuclide(s), and may detect neutron sources.
An indication shall be provided when the measurement results from the detection system exceed an alarm criterion or pre-set condition (user selectable for radiation level or identification result). Measurement occurs when the object passes through the detection zone (transient mode) or with the object static within the detection zone where the user performs controlled analyses of the object (i.e., enters collection time and/or activates the count to obtain a spectrum).
Passage speeds for transient mode testing are stated in each applicable clause and summarized in Table 2. Testing at different speeds may be performed as a special test upon agreement between the manufacturer and user.
Monitors shall be capable of operating independently of any peripheral device or remote station and shall be unaffected by any malfunction of a peripheral device.
According to its use, an SRPM can be classified as a:
– pedestrian monitor,
– small vehicle monitor,
– large road vehicle and rail monitors, or
– package or conveyor monitor.
The detection zone is the area located adjacent to a single-sided detection assembly or between two or more detection assemblies where the measurement of radiation takes place (Figure 1 ). The size of the detection zone is based on the classification of use. If a monitor is used in two or more classifications, its detection zone shall be appropriate for each classification. The detection zone shall be of a size that ensures that all objects which could move through the detection zone are monitored. The manufacturer shall state the SRPM classification(s) for which the requirements stated in this document are met. Operational conditions such as separation distance (distance between opposing detection assemblies), object speed, and background radiation should be considered when installing the monitor. It is important to be able to identify the object that caused an alarm. The alarm should be generated within a period of time to ensure that the object that caused an alarm can be identified. This is important if complex algorithms are in place that need a finite process time. It becomes more important if a constant stream of traffic is being monitored (e.g., pedestrians).IEC 62484 pdf download.