Speaker
Description
The valorisation of refractory waste containing zirconium compounds is of particular interest due to their properties and high cost. This waste can be recycled not only in the refractory materials industry but also, increasingly, in the ceramics industry. However, this refractory waste is NORM due to the presence of impurities from radioactive elements in the natural decay chains of U-238 and Th-232 in zirconium materials. So that, in the valorisation of NORM waste, it is also necessary to consider the safety of professionals exposed, the public, and the environment, which requires justifying, limiting, and optimising its radiological impact.
The aim of this work is to radiologically characterise the refractory waste containing zirconium to determine its compliance with the regulations. In addition, a study was conducted to assess the radiological impact on workers at companies that mill refractory waste in a milling plant, focusing on external and internal doses, the latter arising from inhalation of dust generated during milling.
In view of the results obtained, the activity values of 40K are far from the exemption limit of 10,000 Bq/kg, and the ones of the 232Th chain do not exceed the exemption limit of 1,000 Bq/kg. However, the activities of the 238U chain are above the limit of 1,000 Bq/kg for all the refractories studied. Therefore, a detailed study of these materials was carried out. Regarding the radiological impact on workers of companies that employed refractory wastes, the dose received by the milling operator is higher than that received by the bagging operator, both below the threshold of 1 mSv/year, which could be exceeded without adequate control of airborne dust and exposure time.
Acknowledgements:
Thanks to Generalitat Valenciana (CIAICO/2024/254), the Universitat Politècnica de València (PAID-06-24), and the Agencia Estatal de Investigación (PID2024-156584OB-100, funded by MICIU/AEI/10.13039/501100011033 and by FEDER, EU).