Year
2002
Abstract
In 1995, the International Atomic Energy Agency (IAEA) embarked on a program to replace its aging and obsolete film and videotape based surveillance equipment with systems based on digital image technologies. Following successful laboratory and field testing of three difference digital surveillance systems, the decision was made to standardize all surveillance systems, thereby minimizing the numbers of different types of equipment and the amount of inspector training. In mid 2000, it became evident that the Agency was experiencing higher than expected failures of its newly implemented digital image surveillance systems. Those systems, based on a sophisticated digital camera module (DCM14), formed a family of surveillance equipment designed to cover the complete range of safeguards requirements for single-camera, multi-camera and portable surveillance applications. The DCM14 was developed under the German Member State Support Programme using contemporary state-of-the-art components and techniques to fully meet the Agency’s essential user requirements for safeguards digital surveillance. Analysis of the failure symptoms from the field, and of the results of laboratory tests undertaken to determine the fault mechanism, concluded that most failures were due to higher, than anticipated, neutron radiation levels in the general vicinity of some installed camera units. The presence of radiation induced single event upsets (SEU) in the digital camera module’s sensitive memory components. Once the problem was understood, the DCM14 developer, the manufacturer and the IAEA, with the assistance of the USA and German Member State Support Programmes moved quickly to establish and confirm the failure mechanism. By adopting techniques used in the aerospace industry to self-correct a system in the event of a SEU, and through the selection of more radiation tolerant components, the DCM14 was strengthened to make it more reliable when operating in moderate levels of neutron radiation. This paper will review the DCM14 and its functions, discuss the observed problems and present the solutions that were used to improve its reliability. Finally, the paper will provide data demonstrating the overall improvement in the reliability of the Agency’s surveillance systems.