Reliability evaluation studies of aerial gamma spectrometry system

The Aerial Gamma Spectrometry System (AGSS) is a field instrument developed in Bhabha Atomic Research Centre for quick qualitative and quantitative assessment of radioactive contamination over large area on ground in case of a major nuclear/radiological emergency. This necessitates the system to be operated for aerial surveys above complex topography and harsh environmental conditions. The AGSS has been designed taking into consideration all operational aspects with allowance for variations in parameters such as current, voltage, temperature, humidity etc. The measures taken at the design stage of the AGSS are intended to ensure the reliability of the system during the survey operations under various environmental conditions. The AGSS has been built around an Industrial Computer and consists of NaI(Tl) Detector, Signal Processing Module and Data Storage and Interface Module, which are PC add-on cards and a Global Positioning System (GPS). The Industrial Computer, GPS and the detector are commercially available and they have undergone reliability assessment by the manufacturer. The reliability assessment studies of the Signal Processing and the Data storage and Interface modules have been done in-house. This paper describes the details of the reliability study carried out on AGSS components. The results of reliability evaluation show that the AGSS will provide reliable service if operated well within the limits of operating conditions during aerial/field surveys. The chances of functional failure of AGSS are found to be less than two times in thousand operations of eight hours duration each. (author)