Development of a microcontroller based vehicle monitor using plastic scintillator detector

Full text: The regular operation of nuclear facilities generates significant amounts of radioactive and non radioactive wastes. Often there is a possibility of these getting mixed up and inadvertently being sent for recycling leading to radioactive contamination in the public domain. It is mandatory that all scrap and garbage generated in and around nuclear facilities are monitored before being sent out for recycling or dumping. This becomes more important particularly during the decommissioning of reactors when optimization of the amount nuclear waste generated is very important. A very effective method for monitoring is by using large volume plastic scintillator detectors. The Vehicle Monitoring System (VMS) that was developed for this purpose uses four plastic scintillator detectors of 0.05 m diameter and 0.5 m length. The system designed and was calibrated to independently measure the radiation field of each detector. The hardware for the system was developed using Philips 80C552 microcontroller based Single Board Computer (SBC). The microcontroller software was developed using Keil environment on a Windows Platform. The counts recorded for 5 seconds are sent to the PC continuously. As a backup the minutely average data is also stored in the SBC RAM and can be transferred to the PC on request. The SBC RAM can store the 18 hours data. A watchdog timer was also incorporated in the SBC software to keep it operational after a system hang up due to any unforeseen electrical disturbances. The scrap containing vehicles or trucks to be monitored have to be stationed on the road alongside the Vehicle Monitor. The radiation field data is sent to a remote PC for analysis and storage. A comparative study was done with a Gamma Tracer with the average of the data from 4 detectors. There was very good correlation between data from the two systems. The Vehicle Monitor has much more stability and sensitivity as compared with Gamma Tracer. Apart from vehicle monitoring, the system continuously acquires data and can also be used to study the variations in the ambient radiation background