131I and 99mTc in Effluents from a Nuclear Medicine Facility and Associated Sewage Treatment Unit
2021
do Carmo, Alessander Sá | Vianello, Elizabeth Aparecida | Pereira, Wagner | de Macêdo, Evangelina Marcia Lima | Filho, Lucas Gomes Padilha | de Souza, Sérgio Augusto Lopes | da Silva, Ademir Xavier
The release of liquid effluents containing radionuclides from radioactive plants in urban areas has been the subject of discussions related to the environmental issue. This study presents the analysis of the activity concentrations (AC) of ¹³¹I and ⁹⁹ᵐTc in sewage samples collected in a nuclear medicine facility (NMF), associated with an university hospital situated in Rio de Janeiro, Brazil. The analyzes and measurements by gamma spectrometry of the collected sewage samples were performed, whose the estimated values (EV) for AC obtained for ¹³¹I in July (8.78 × 10³ Bq m⁻³) and September 2016 (9.80 × 10³ Bq m⁻³) and in February 2017 (1.14 × 10⁴ Bq m⁻³) were lower than the exemption level (EL = 1.90 × 10⁴ Bq m⁻³). For ⁹⁹ᵐTc, the EV for AC obtained from August (4.77 × 10² Bq m⁻³ and 2.96 × 10⁴ Bq m⁻³) to September 2017 (2.18 × 10³ Bq m⁻³) were lower than the EL (1.90 × 10⁹ Bq m⁻³). From an environmental point of view, the presence of ¹³¹I in the sewage treatment unit (STU), even if below the legal release limit, points out the greater importance of this radionuclide, as it requires special precautions in its adequate storage for the radioactive decay in the NMF and the dilution effect to reduce its AC minimizing the environmental impact after the effluent release to the environment. The presence of ¹³¹I in the STU was not expected pointing to the need and evaluation of the waste management system (WMS) of the NMF.
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