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 of nuclear facilities. Clearance levels are established by regulatory authorities and are normally quite low. Determination of those activity concentration levels becomes more difficult when it is necessary to quantify alpha emitters such as uranium, especially when complex matrixes are involved. In addition, an adequate workplace monitoring must be carried out during the decommissioning 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 sample 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 among the different techniques was also performed by analysing the results obtained in some practical applications.