Effect of laser parameters on the measurement of U/Nd ratio using pulsed laser deposition followed by isotopic dilution mass spectrometry

Nd-YAG laser pulses of 1064, 532, 266 nm in wavelength and of 8 ns and 100 ps in pulse width as well as KrF excimer laser pulses (248 nm) of 30 ns pulse width were employed to deposit thin films of the simulated spent nuclear fuel pellets. The deposited thin films were dissolved in nitric acid and analyzed for residual heavy element (U) to burn-up monitor (Nd) ratio using isotopic dilution mass spectrometry (employing the TIMS technique) to determine the burn-up in these simulated fuel pellets. While the use of ns-laser pulses of 1064 nm wavelength resulted in high elemental fractionation with enhanced Nd concentration compared to the target composition, the 266 nm ps-laser pulses produce films with least elemental fractionation in the film and hence is best suited for this analytical application. Due to the very small amount of material in the deposited film and the amenability of pulsed laser deposition system for use in radioactive shielded hot cells, this analytical technique is suitable for sampling highly radioactive materials.