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Engineering science >> Metrology
1 proposition(s).

Characterization of X-ray emitting radionuclides - Application to reactor dosimetry


Laboratoire de Métrologie de l'Activité



The activity measurement of X-ray emitting radionuclides in the energy range below 100 keV encounters several difficulties that limit the accuracy of the result. These include the difficulty of calibrating detector performance and, in general, the significant uncertainties associated with emission intensities X. In addition, the self-absorption effects of X-rays in standard sources or samples lead to important corrections that must be controlled. Among the important applications of X-emitter measurement, reactor dosimetry, which makes it possible to determine the neutron fluence received during irradiation and to characterize its spectrum, is based on the analysis of the activity of irradiated dosimeters. These are made of pure metals or alloys of perfectly known compositions, some of which are activated or fissioned by neutrons. For example, reactions 93Nb(n,n')93Nbm and 103Rh(n,n')103Rhm are of prime importance for reactor dosimetry and are particularly interesting for characterizing neutron fluxes around 1 MeV. The proposed work follows a thesis that identified several areas for improvement in dosimeter measurement that will need to be implemented, including : - improvement of radionuclide X-ray emission data used as standard for calibration (133Ba, 152Eu, etc.) to establish a consistent set of data; - validation of corrective coefficients due to the presence of impurities during dosimeter irradiation; - evaluation and publication of the decay scheme of 103Pd and 103mRh; - implementation of a new method of performance calibration using monochromatic radiation.

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