Uranium determination in samples from decommissioning of nuclear facilities related to the first stage of the nuclear fuel cycle

Large amounts of waste materials are generated during the decommissioning o f nuclear facilities. Clearance levels are established by regulatory author ities and are normally quite low. Determination of those activity concentra tion levels becomes more difficult when it is necessary to quantify alpha e mitters such as uranium, especially when complex matrixes are involved. In addition, an adequate workplace monitoring must be carried out during the d ecommissioning activities, to ensure the protection of workers involved in these tasks. Several methods for uranium determination in samples obtained during the decommissioning of a facility related to the first stage of the nuclear fuel cycle are presented in this work. According to the kind and sa mple size, together with the minimum detectable activity (MDA) that must be reached in each case, measurements were carried out by laboratory and 'in situ' gamma spectrometry, as well as by alpha spectrometry. A comparison am ong the different techniques was also performed by analysing the results ob tained in some practical applications. (C) 2000 Elsevier Science Ltd. All r ights reserved.