**4.2. Recycling equipment**

The contamination produced from the accumulation of toxic materials mainly include heavy metals such as mercury and radioactive materials of the natural origin (e.g., 226Ra, 228Ra, 210Pb). For decontamination purpose, the contaminated equipments were taken into melting plant, especially built for this process; its annual capacity is 2000 tones of steel and metal scrap contaminated with mercury and TE-NORM. After melting, the radiological measurements showed that the produced metal did not contain any detectable residual of TE-NORM, and can be re-used again in steel works. About 98% of TE-NORM were bound to the slag and ~2% were detected in the filter dust, mainly consisting of the nuclides 210Pb and 210Po. The secondary waste produced is ∼43% of the total weight of the material supplied, whereas TE-NORM waste consists of ~95% of slag and ~5% coarse dust [45].

Chemical separation of the radionuclides incorporated in the contaminated equipment (pipelines, tubes, pumps) is carried out by melting at 1400°C, to further fractionation of radionuclides in melt, slag, or dust. The analysis of data showed that most of 238U and 232Th series are transferred from melt (dense main component, contains only 1% of the remainder radioactivity) into the slag (light minor component, contains only 98% of the total radioactiv‐ ity). All activity of 210Pb was concentrated in the filter dust, because it is evaporated at normal melting temperature above 1300°C [47]. Equipment should be decontaminated to less than 0.4 Bq/cm2 for alpha emitters or 4 Bq/cm2 for beta and gamma emitter, before any release.
