Improving radioactivity measurements in steelwork products
JRC scientists contributed to the optimisation of detector systems to check the radioactivity in metallurgical samples. This work will support the safety of recycling process of, for example, decommissioned materials. Despite applied controls, using portal monitors and other checks of materials entering metal foundries, an "orphan" radioactive source may pass undetected into the steel smelting process. Its accidental melting together with the scrap metal will result in contamination of furnaces, metal products, by-products and the environment with radionuclides.
To improve and harmonise the detection of radioactivity in steelworks, scientists from the JRC-Institute for Reference Materials (IRMM) have developed, within a European collaboration with 13 European National Metrology Institutes, new reference materials and methods. One major output was the designing of a novel radionuclide specific detector system for the measurement of gamma-emitting radionuclides in metallurgical samples. The recommended system consists of a so-called "extended-range germanium semiconductor detector" for detecting gamma-rays, a sample chamber and lead shielding designed to accommodate typical metallurgical samples and tables of efficiency values and correction factors to make the system useful for different types of industries, radionuclides and samples. The latter tables were calculated using Monte Carlo simulations, involving computer models of the detector. Additionally, special versions of the Monte Carlo codes have been made available for end-users to run simulations on their own and to calculate correction factors for additional sample types.
The prototypes of the system were also demonstrated and tested at end-user facilities All developed computer models along with a guidance document for their implementation are freely available to end-users. The implementation of the new characterised systems is expected to reduce the likelihood of leakage of radioactivity into the environment via the metallurgy route, as well as the associated human health risk and international trade disputes.