Design and construction of a vehicle radiation portal monitor to detect radioactive materials

The design and construction of a radiation portal monitor for the detection of radioactive materials and pollution, the control of the transportation of radioactive materials, and the inspection and identification of radioactive materials in customs, with an emphasis on monitoring the inner space of vehicles and truckloads, was carried out in Iran's Radiation Application Development Company (IRAD Co.). The radiation portal monitor can be installed as a gate on both sides of the entrance of factories, nuclear facilities, customs, airports and borders, and it is considered a new way to deal with the dangers caused by radioactive materials. This system is sensitive to very low levels of radioactive contamination. It comprises electronic circuits, mechanical holders, and four plastic scintillation detectors as a monitoring system. Some of the equipment of this system include a camera for taking photos of the license plate, ability to install the automatic control barrier, the remote-control center, the indicator light to inform the driver of the situation, and the visual and audio warning signs. Functional tests using a 137Cs source with an activity of 3 µci showed that the radiation portal monitor could detect a source inside the car with a minimum activity of 3 µci at a range of 100 cm. This system is also very accurate in identifying the same source when it moves at a maximum speed of 1.4 m/s.