Synchrotron radiation induced total reflection X-ray fluorescence (TXRF) and conventional 45 degrees energy dispersive X-ray fluorescence analysis (EDXRF) using a 150-nm-thick AP1 (TM) film as sample carrier have been exploited for the elemental analysis of traces in alloys used for the construction of reactor core components of nuclear power plants. Both techniques are well suited for the analysis since they require a low amount of sample (mul), important on one hand because of the limited disposal and on the other hand because of its high specific activity. The methods provide a very low background due to the total reflection phenomenon in TXRF and the thin AP1 (TM) film sample support, respectively. The employment of synchrotron radiation was necessary since there are no laboratory sources which can deliver a collimated beam of the energy and intensity needed to excite the K-shell of the rare earth elements, allowing the achievement of minimum detection limits relevant for the proposed purpose (ng/g range). Moreover, the linear polarization of synchrotron radiation combined with a side-looking detection geometry manages to reduce the scattering due to the remaining matrix of the analyzed samples. Detection limits for Nb and for some of the rare earth elements (pg range for absolute detection limits and ng-mug/g range for concentration detection limits) obtained with the two techniques are presented and the two approaches are compared. (C) 2001 Elsevier Science B.V. All rights reserved.