Synchrotron μ-XRF study on compositional uniformity of uranium-thorium oxide pellets prepared by different processes

A mu-XRF study to assess the distribution of uranium and thorium in (U,Th)O-2 pellets covering the composition of advanced heavy water reactor (AHWR) fuel pellets prepared by powder metallurgical compaction (PMC) and coated agglomerate pelletization (CAP) routes was made using micro-focus beam line (BL-16) of Indus-2 synchrotron radiation facility. The methodology thus developed was successfully applied to these pellets. The study reveals that the uranium distribution in pellets prepared by PMC route is uniform, whereas the pellets prepared through CAP route have a wide range of compositional variation. In addition, the uniformity in CAP route-prepared pellets improves with increase in the relative amount of uranium in the pellets. The sample preparation in present methodology is very simple compared with scanning electron microscopy. The study reveals the utility of synchrotron-based mu-XRF for fuel pellet characterization of AHWR reactors. Alhough CAP route of fuel pellet preparation requires less exposure of personnel to high radiation dose, the non-uniformity in the fuel pellet must be considered when using these pellets in reactors. Copyright (c) 2014 John Wiley & Sons, Ltd.