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 H-3 and C-14 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 H-3 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 H-3 and C-14 speciations are discussed. Consequently, a drilling sampling technique was developed in order to capture the released H-3 and C-14 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 H-3 and C-14 (activity concentration and speciation) using a thermal oxidation technique. The results showed that a significant amount of H-3 was released during sampling even though the majority of H-3 was strongly bound in the activated concrete. The studied activated concrete did not contain measurable amount of C-14 and therefore speciation studies were not possible.

Automated summary

Characterisation of contaminated and activated decommissioning waste requires sampling of the studied material for the analysis of different radionuclides. In this study, a drilling sampling technique was developed to capture released H-3 and C-14 for analysis. The results showed a significant amount of H-3 released during sampling, while C-14 was not measurable in the studied activated concrete, limiting further speciation studies.