An evaluation of two sample preparation methods for measuring 3H and 14C in incinerator ash and spent lime

This paper compares the performance of two methodologies, oxidation and gel suspension, for measuring the 3H and 14C specific activity in incinerator ash and lime. The two methods were judged on the basis of the count time needed to achieve a specified minimum detectable concentration. Both methods involve pretreatment of the sample matrix followed by liquid scintillation counting. Both methods perform adequately for measuring 3H in spent lime, but only oxidation delivers adequate sensitivity for the more demanding 14C case. In addition, the gel suspension method fails to detect over 95% of the 3H seen by the oxidation method in incinerator ash.