Improvement of

Reactor dosimetry is based on the analysis of the activity of irradiated dosimeters, such as 93mNb and 103mRh. The activity measurement of these dosimeters is conventionally performed by X-ray spectrometry, but the low-energy of emitted photons makes it difficult to derive reliable results with low uncertainties. Approaches to improve these characterisations are presented: they include high accuracy efficiency calibration of a HPGe detector using both experiments and Monte Carlo simulation, calculation of corrective factors for the geometry (selfabsorption) and self-fluorescence effects. Improvement of the knowledge of the 103mRh decay scheme is also required and a specific experiment is proposed, including activity measurement of a 103mRh solution by liquid scintillation, and measurement of the photon emission intensities by X-ray spectrometry. A method for calculating coefficients to take into account the self-fluorescence effects in dosimeters is also suggested to improve the uncertainties on activity measurements