Year
1988
Abstract
The Euratom Safeguards Directorate (ESD) currently operates 8 high resolution gamma spectrometers for the determination of Pu isotopics and 19 gamma spectrometers for the measurement of U235 enrichment. The use of these instruments has been increasing continuously over the last years. With the introduction of a headquarters based computerized archiving and post evaluation system for gamma measurements /1,2/ it is now possible to carry out quality control and measurement performance evaluation based on a large number of measurements. This paper reports inspector-operator differences for different nuclear materials both for Pu isotopics and U235 enrichment. Pu measurements range from fresh Pu nitrate solutions and Pu oxide powders at reprocessing plants through fast breeder and LWR mox powders and pellets to fast breeder and LWR mox pins and include very low burn-up and very high burn-up material. U235 enrichment measurements cover UF6, uranium oxide powders and pellets and MTR elements. Different factors contributing to the inspector-operator differences are discussed. Problems with hardware, software and measurement procedure are identified. The paper also discusses limitations of existing algorithms for Pu isotopics and reports the first results achieved in-field with a new advanced algorithm /3/. Instrument use and failure statistics are also presented. In the light of the main problems identified, draft specifications for the next generation of ESD gamma spectroscopy equipment are put forward.