Decommissioning and demolition of a dicalcium phosphate plant: aspects of radiological protection and safety
DOI:
https://doi.org/10.15392/2319-0612.2024.2482Keywords:
decommissioning, radiation protection, dicalcium phosphate, radiation monitoringAbstract
The detection of ionising radiation in materials from the decommissioning of a dicalcium phosphate plant meant that this whole operation had to be overhauled in terms of radiological protection and safety. Thus, an operations plan was drawn up that included: initial training for all workers involved, measurements of dose rates and a set of analyses by gamma and alpha spectrometry. Samples of "dry sludge" and debris were analysed for the identification and quantification of the radionuclides present, samples of workers' urine were analysed for the detection of any internal contamination, samples of washing water and air filters were analysed for the detection and control of any radioactive atmospheric contamination. In addition, individual dosimeters were distributed to workers. The extent of contamination was identified and the areas where higher values were detected were properly marked. From the results obtained (radiation dose rates and activity concentrations), it was possible to establish categories and separate the contaminated materials according to their physical characteristics. After the plant decommissioning, the resulting waste with dose rates higher than the effective dose limits for the public was packed in big bags. These bags were divided in 3 groups according to the external radiation dose rates at contact. This segregation allowed the competent authority to release a significant number of big bags from regulatory control. The remaining big bags are stored in two metal containers subject to regular radiological monitoring. The objective of this work is the presentation of a factual article where the methodology implemented to deal with this situation, which had never occurred in Portugal, is described, having only the Portuguese legislation as a reference.
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IAEA-TECDOC-1712, Management of Norm Residues, Vienna, June 2023, ISBN 978-92-0-142710-6.
Decree-Law No. 156/2013, of November 5: establishes the legal and regulatory framework for the responsible and safe management of spent fuel and radioactive waste and transposes into Portuguese law the provisions of Council Directive 2011/70/Euratom of 19 July 2011.
Ordinance No. 138/2019, of May 10: approves the exemption and release criteria.
Decree-Law No. 108/2018, of December 3: establishes the legal framework for radiological protection, as well as the powers of the competent authority and the inspection authority for radiological protection, transposing into Portuguese law Council Directive 2013/59/Euratom of 5th December 2013 laying down basic safety standards for protection against the dangers arising from exposure to ionising radiation.
Decree-Law No. 81/2022, of December 6: amends the legal regime Portuguese of radiological protection, adapting the rules on incompatibilities to the administrative offence regime and application.
Resolution of the Council of Ministers No. 129/2022, of December 20: approves the National Portuguese Program for the Management of Spent Fuel and Radioactive Waste.
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