Measurement Method Of ～(99)Tc With Accelerator Mass Spectrometry

⁹⁹Tc is a fission product; it has high and abundant fission yield (6.13%) and a very long half-life (2.13×10⁵a). A great deal of Tc is produced in nuclear weapon testing, unclear fuel cycle, and nuclear medicine and so on. ⁹⁹Tc has been widely distributed in environment. It is difficult to measure with decay counting methods due to its long half-life. Due to the existence of the interferent of the stable isobar Ru and molecules ions, the common Mass spectrometry is also difficult to detect the ⁹⁹Tc with high sensitivity. The AMS is able to measure small amount of ⁹⁹Tc with higher sensitivity.This work is supported by the National Natural Science Foundation. The goal is to establish an ideal ⁹⁹Tc measurement method. The main aims of this work are as follows: the first is the AMS samples preparation of ⁹⁹Tc, including blank samples , standard samples and the unknown environment samples. The second is the ⁹⁹Tc measurement with AMS: the known ⁹³Nb replace the isotope of ⁹⁹Tc .The content of ⁹⁹Tc in unknown samples can be obtain by measuring ⁹⁹Tc /⁹³Nb ratio of unknown samples and standard samples.⁹⁹Ru is the main interference in the measurement of ⁹⁹Tc. Removing ⁹⁹Ru in the samples by using chemical method and identifying ⁹⁹Ru by physical detector is the key method for AMS measurement with higher sensitivity. Extracting TcO^- from ion source after dealing the samples by the TEVA resin, Ru as the major interference can be largely reduced down about 1000 times. ⁹⁹Tc is successfully identified and finally quantified by using a multi-anode detector and measuring the isotope ¹⁰¹Ru to correct ⁹⁹Ru, the sensitivity for the atomic ratio of ⁹⁹Tc/⁹³Nb is 4×10¹¹,accodding to the background of ⁹⁹Ru ,the detection limit of ⁹⁹Tc is about 10 atom.Developing the chemical flow for standard samples, water samples and soil samples, participating the AMS measurement and analyzing the experimental data are my main contribution.