Behaviour of radionuclides in the melting of steel

In general the melt experiments confirmed the expected behaviour of the radionuclides selected for the experiments. 55Fe and 63Ni distribute homogeneously in the metal ingot as was expected from the behaviour of 60Co. The latter radionuclide may be used as an indicator nuclide for 55Fe and 63Ni which are both difficult to measure. 14C shows a comparable behaviour and is homogeneously distributed in carbon steel. As expected strontium is released to the slag in the melt process. In principle this is valid for actinides too. The behaviour of actinides in the melt process depends to some extent on the chemical form (elemental uranium, UO2), the added tracer quantity and the quantity of slag forming material added in the melt process. A direct α-measurement technique was developed to measure α-radionuclides in steel samples. Only this type of measurement has to be applied in case of α-emitters as a decision measurement to assure that the steel decontaminated by the melt process can be released for unrestricted reuse. (author)