Verhalten von Tritium in Reaktorgraphiten

This report gives information about laboratory experiments an the behaviour of tritium and hydrogen in different graphite materials,which are interesting for the HTR . With the aid of especially developed vacuum devices the diffusion and adsorption kinetics is measured isothermally and by the flash-filament-method. The detection of hydrogen is made by means of a mass spectrometric method. The tritium is measured after catalytic oxidation by liquid-scintillation . An absolute determination of the total content of tritium and hydrogen in the samples is attained by ashing and subsequent analysis of the combustion gases. From the measurements diffusion coefficients and desorption energies are evaluated. When these results are taken into account for the operation of the HTR, it can be stated that the actual tritium inventory is largely determined by the baffer properties of the graphite core. Thus, in the starting phase of HTRs, when higher tritium production rates are to be expected, the coolant gas activity which is responsible for a tritium permeation through the heat exchangers, remains small. The predominant part of the produced tritium will be obtained in the reprocessing plants