Modernization of EURATOM's unattended measurement stations at Melox MOX Fuel Fabrication and La Hague Reprocessing Plants

Abstract

The Nuclear Safeguards Directorate performs rigorous controls of the bulk handling nuclear materials sites. The inspectors are present from 25 to 50 percent of the working days in the Melox MOX Fuel Fabrication Plant and the La Hague Reprocessing Plant. The installed independent EURATOM measurement stations assure continuous measurements allowing the inspectors to verify 100 percent of the nuclear material flow across critical points in those facilities. For security reasons, access to these measurement points is usually very restricted. The reliability and high availability of these measurement stations is thus of high significance. Some of them were continuously operating for over 20 years without major maintenance before the upgrade discussed in this paper. Six unattended measurement stations, consisting of neutron coincidence collars and electromechanically cooled high purity Germanium detectors have been modernized recently. The reliability of the automated data acquisition system has been significantly improved. The availability of the data transmission networks was improved at the same time. The number of interventions as well as the historically high maintenance costs for the measurement stations is expected to be much lower in the future. This paper describes a number of complex problems that needed to be solved, including the successful technical solutions used for the reduction of EMI (Electro-Magnetic Interference). An overview with respect to the ageing problems of the components of measurement stations discovered during their in depth maintenance will be provided.