Isotope Dilution - Multiple Collector Inductively Coupled Plasma Mass Spectrometry (id-mc-icp-ms) Measurement Of ~ (148) Nd Method

The basic characters of neodymium and the applications in nuclear industry, several measurement methods of bum-up, the basic principles of mass spectrometry and the knowledge of isotope dilution are introduced in the paper.In the work determination of concentration of isotope ¹⁴⁸Nd in fission products were studied using MC-ICP-MS. Optimum concentration, measurement time, torch position, nebulizer gas flow rate, collision gas flow rate and ion lens system were researched. The optimization parameters were achieved and the precision of isotopic ratio is better than 0.01%. The stability of mass spectrometry instrument was tested using two kinds of standard materials and the difference of two correct factors was less than 0.001%.The isotope dilution technique was applied for measuring the isotopic ratios of neodymium. Two steps of work were studied in the research. One is that the concentration of the ¹⁴⁴Nd spike was measured using the natural neodymium. And the other is that the concentration of the sample was measured using the¹⁴⁴Nd spike. The relative standard deviation is better than 0.3%. The advantage of this method is simple sample preparation, small quantity of sampling and fast speed of measurement in comparison with TIMS. A new measurement method is established in our laboratory.A mathematical model was established for the uncertainty evaluation in the measurement. This paper evaluated the uncertainty of the testing result, provided with the collection of all the parameters and the calculation methods needs for the calculation process, and evaluated the values of standard uncertainty, combined standard uncertainty and expanded uncertainty.