Release of ³H and ¹⁴C during sampling and speciation in activated concrete

Characterisation of contaminated and activated decommissioning waste require sampling of the studied material for the analysis of different radionuclides. The volatility of ³H and ¹⁴C can lead to the loss of the analytes in sampling of solid materials since most often at least some heat is involved in the sampling technique. Especially ³H can be lost in cases when it is present as tritiated water (HTO) due to the evaporation of water even at low temperatures. Therefore, in this study, the ³H and ¹⁴C speciations are discussed. Consequently, a drilling sampling technique was developed in order to capture the released ³H and ¹⁴C in absorption solutions and measured using liquid scintillation counting. The sampling technique was tested on an activated concrete core. The collected samples were analysed for ³H and ¹⁴C (activity concentration and speciation) using a thermal oxidation technique. The results showed that a significant amount of ³H was released during sampling even though the majority of ³H was strongly bound in the activated concrete. The studied activated concrete did not contain measurable amount of ¹⁴C and therefore speciation studies were not possible.