Spectrometric methods for trace metal assay of nuclear fuels

India proposes to utilize natural U and Pu in successive stages for its nuclear power programme. Presence of trace elements in nuclear materials affects the nuclear reactor operation and breeding significantly. It is necessary, therefore, to develop analytical methods for trace metal assay in a wide variety of these samples. Analytical methods based on atomic emission spectrometry (AES) provide simultaneous multi-element analysis and are generally preferred over other trace analysis techniques. Atomic absorption spectrometry (AAS) being a single element technique is mainly used as a complementary method to AES. The present paper describes the different analytical methodologies developed using spectroscopic techniques for trace metal assay of various nuclear materials. Certified reference materials of U3O8, ThO2 and (U,Th)O2 with regard to trace metallic constituents were prepared with the involvement of thirteen DAE laboratories. Recent efforts to set up an ICP-AAS system for ultra trace analysis of certain critical impurities and use of EDXRF technique as an analytical tool for a few major and minor constituents is also discussed. (author)