Secondary ion mass spectrometry (SIMS) analysis has been used to measure isotope ratios of selected impurity elements in irradiated reactor materials. Samples of reactor materials such as graphite or aluminum alloys are obtained from fuel channels or supporting materials. During reactor operations and fuel burn up, some isotopic abundances change due to nuclear reactions and provide sensitive indicators of neutron fluence. The rate of change is related to cross section for a particular isotope. Different isotopes can be used as indicators of burn up during different stages in the reactor operating history. Isotope ratios of B are useful indicators for low burnup stages early in reactor operations, Ti isotope ratios are useful at later burn up stages, and Cl isotope ratios are useful in both early and later stages. Knowledge of the sample position within the reactor also yields information on the fluence shape or profile. In a sequence of samples from one reactor, 10B/11B ratios decreased from near natural values of 0.25 to
Revised: April 7, 2011 |
Published: July 30, 2006
Citation
Gerlach D.C., J.B. Cliff, D.E. Hurley, B.D. Reid, W.W. Little, G.H. Meriwether, and A.J. Wickham, et al. 2006."Secondary Ionization Mass Spectrometric Analysis of Impurity Element Isotope Ratios in Nuclear Reactor Materials." In SIMS XV 2005, 15th International Conference on Secondary Ion Mass Spectrometry 12–16 September 2005 Manchester, UK. Published in Applied Surface Science, 252, 7041-7044. Amsterdam:Elsevier Science BV.PNNL-SA-46080.