This paper is devoted to the development of a new approach towards elemental analysis in spent nuclear fuel (SNF) technological solutions. The approach is based on the registration of X-ray fluorescence (XRF) induced by the radioactivity of the SNF samples and consequent chemometric processing of the acquired XRF spectra. Here we extend this approach towards a challenging case of lanthanide quantification – due to the similar electronic structures of these elements their XRF lines are strongly overlapped. Multiple sources of radiation severely deteriorate the quality of the spectra. Nevertheless, multivariate regression models allows attaining technologically sufficient accuracy of quantification for La, Ce and Nd in 0.1–4.8 g/L concentration range with RMSE around 0.3–0.5 g/L depending on the element.