Low-level liquid scitillation counting for quantification of annual 3H and 14C concentrations in tree disks

The government of Schleswig Holstein funded a study to perform the retrospective determination of airborne 3H and 14C concentrations. It is well known, that in tree rings most of the hydrogen and cabron is fixed after insertion in the matrix of wood and that the radionuclide concentration correlates with former airborne activity concentrations. For the retrospective study wood disks of trees located in the region near the nuclear power plant of Kruemmel and control disks of unsuspected areas were selected. The hydrogen of the wood was transformed to water and the carbon to carbondioxide by classical oxidation processes (combustion in a furnace). The contents of 3H in the water and 14C of the carbondioxide (solved in scintillation liquid) were determined by liquid scintillation counting, using a low-level counter (type Quantulus 1220, Wallac). (orig.)