Investigations on plutonium determination employing isotope dilution technique using mass spectrometry and alpha spectrometry

Isotope dilution methods using mass spectrometry and alpha spectrometry are invaluable in complex matrices such as the dissolver solution of irradiated fuel and the environmental samples. We have carried out a comparative study on the use of different spikes viz. 239Pu, 240Pu, 242Pu in isotope dilution thermal ionization mass spectrometry and shown that the use of 239Pu spike is advantageous as it gives less isotopic fractionation and can be easily obtained. It is advocated that the 244Pu spike should be used only along with 242Pu spike, while using a double spike technique. In the isotope dilution alpha spectrometry, we have used 238Pu as a spike which can be easily obtained from thermal neutron irradiation of 237Np. The merits and drawbacks of this spike compared to other spikes 236Pu and 242Pu, which are difficult to obtain, will be discussed