Every year millions tons of steel are produced worldwide from recycled scrap loads.
Although the detection systems in the steelworks prevent most orphan radioactive sources
from entering the furnace, there is still the possibility of accidentally melting a
radioactive source. The MetroMetal project, carried out in the frame of the European
Metrology Research Programme (EMRP), addresses this problem by studying the existing
measurement systems, developing sets of reference sources in various matrices (cast steel,
slag, fume dust) and proposing new detection instruments. This paper presents the key
lines of the project and describes the preparation of radioactive sources as well as the
intercomparison exercises used to test the calibration and correction methods proposed
within the project.