Hasil untuk "Radioactivity and radioactive substances"

Hugo Leonardo Lemos Silva, Noil Amorim de Menezes Cussiol, Tarcísio Passos Ribeiro de Campos

Healthcare waste (HCW) requires efficient treatment prior to final disposal to prevent the spread of pathogens and environmental contamination. Ionizing irradiation has emerged as a promising alternative to incineration; however, accurate absorbed-dose determination depends on knowledge of the material’s radiological properties. This work aims to develop a physical simulator for HCW to support dosimetric evaluation of irradiated waste, including experimental and computational validation. Data from the National Institute of Standards and Technology (NIST), along with the XCOM and ESTAR programs, were used to obtain mass energy-absorption coefficients for photons and mass stopping power for electrons in the energy range of 0.1 to 20 MeV. Two approaches were considered: a full compositional model representative of typical HCW, and a simplified model based on Polylactic Acid (PLA), containing only C, O, and H, assuming that PLA adequately reproduces the predominant elemental fraction of the waste. Dosimetric validation was performed by comparing mass attenuation coefficients (μ) and stopping power (S) between HCW and PLA. Computational simulations using PHITS evaluated the spatial dose distribution from photons and electrons. A physical simulator was subsequently manufactured by 3D printing in PLA, with a density of 0.15 g/cm³ and internal hexagonal geometry to reflect realistic waste packing characteristics. Comparisons of attenuation and stopping power coefficients showed minimal differences between HCW and PLA, demonstrating radiological equivalence. Simulations and analyses confirmed that the simulator effectively reproduces the spatial dose distribution, with good homogeneity and fidelity to real behavior. The use of PLA proved to be a practical, economical, and technically consistent solution for constructing simulators aimed at improving dosimetric processes in ionizing radiation treatment of healthcare waste, while also enabling reproducible studies with strong potential for practical application.

Lucas Rezende, Paulo Ferreira, Fernando Ribeiro

Radon is a natural radioactive element responsible for around 40% of the annual dose from natural sources of radiation. It is considered the second leading cause of lung cancer by UNSCEAR. For these reasons, it is important to determine the concentration of radon in built environments. The aim of this study was to quantify the concentration of radon on the premises of the Institute of Radioprotection and Dosimetry (IRD/CNEN). Radon concentrations were measured using CR-39 solid-state nuclear trace detectors, which were exposed for 90 days in 20 of the Institute's buildings, including rooms, offices, bathrooms and laboratories. The laboratorial procedures were conducted at the Radon Laboratory of the Environmental and Occupational Radioprotection Division (DIRAD) of the IRD/CNEN. The statistical uncertainties were provided by the equipment manufacturer's software, and the effective dose calculations strictly followed the appropriate bibliographical references. The average radon concentration found was 86.4 Bq/m³, ranging from 6.5 Bq/m³ to 285.4 Bq/m³, demonstrating compliance with national regulations. Regarding the maximum annual effective dose, for a 5-hour working day, the values ranged from 0.13 mSv/year to 1.33 mSv/year. For an 8-hour working day, the values ranged from 0.21 mSv/year to 2.14 mSv/year. Based on the concentrations obtained, it was possible to check whether the Institute's facilities meet the requirements of standard CNEN NN 3.01, as well as calculating the maximum annual effective dose for two scenarios: 5-hour and 8-hour working days.

Lorena Fonseca, Daniel Silva Calheiro, Amir Mesquita et al.

The use of ionizing radiation has significantly expanded, particularly in the healthcare sector, where the irradiation of blood components prevents transfusion-associated graft-versus-host disease (TA-GvHD). The ISO ASTM 51939:2017 standard establishes a minimum dose of 25 Gy for this procedure, requiring a precise and traceable dosimetric system. This study investigates the calibration of MTS-N thermoluminescent dosimeters at the Gamma Irradiation Laboratory (LIG) of CDTN, which currently uses radiochromic films for routine dosimetry. The dosimeters were calibrated using a RISØ TL/OSL DA-20 reader, and the results indicated that doses above 5 Gy caused reader saturation, distorting the TL emission curve. The introduction of attenuating filters maintained linearity up to 25 Gy, and the calibration coefficient was determined as 6.774×10⁻⁷ Gy/Count, confirming the system’s suitability for dosimetry in blood irradiation at LIG/CDTN.

Noy Vaisleib, Michal Arbel-Haddad, Amir Goldbourt

Geopolymers are aluminosilicate materials that exhibit effective immobilization properties for low-level radioactive nuclear waste, and more specifically for the immobilization of radioactive cesium. The identification of the cesium-binding sites and their distribution between the different phases making up the geopolymeric matrix can be obtained using solid-state NMR measurements of the quadrupolar spin 133Cs, which is a surrogate for the radioactive cesium species present in nuclear waste streams. For quadrupolar nuclei, acquiring two-dimensional multiple-quantum experiments allows the acquisition of more dispersed spectra when multiple sites overlap. However, 133Cs has a spin-7/2 and one of the smallest quadrupole moments, making multiple-quantum excitation highly challenging. In this work we present pulse schemes that enhance the excitation efficiency of 133Cs triple quantum coherences by a factor of ~2 with respect to a two-pulse excitation scheme. The improved schemes were developed by using numerical simulation and verified experimentally by applying one and two-dimensional triple-quantum solid-state NMR experiments to a mixture of cesium-exchanged hydrated zeolites A and X, which possess dynamically averaged small quadrupolar coupling constants in the order of 10 kHz.

Xinshu Xia, Hongbo Huang, Hui Dong

Conventional heat-engine models typically assume two heat reservoirs at fixed temperatures. In contrast, radioisotope power systems introduce a fundamentally different paradigm in which the hot sources supply heat at a constant generation rate rather than maintaining a constant temperature. We develop a theoretical framework for finite-time heat engines operating between constant heat-generation-rate hot sources and constant-temperature cold reservoirs. A universal proportion between average output power and efficiency is established, independent of the specific cycle configuration or working substance. As a representative case, we analyze a finite-time Stirling cycle employing a tailored control protocol that maintains the working substance at constant temperatures during the quasi-isothermal processes. An intrinsic oscillatory behavior emerges in the temperature dynamics of the hot source, reflecting the interplay between heat accumulation and release. We further quantify the long-term decline in engine performance resulting from radioactive decay and demonstrate its impact over the system's operational lifespan. This work establishes a new theoretical prototype for heat engines and shall provide guidings for the analysis and design of radioisotope power systems.

L. M. Ramos, A. F. V. Cortez, M. Kuźniak et al.

To enhance the ionization yield of liquid argon time projection chambers (LArTPC) used in dark matter and neutrino experiments it was proposed the use of dopants in LAr, with ionization energies below the scintillation threshold of Ar. While dual-phase LArTPCs have excellent sensitivity to single ionization electrons, their compatibility with photosensitive dopants is hindered by gas-phase electroluminescence photons ionizing the dopants, leading to a positive feedback loop. This can be addressed by optically decoupling the gaseous and liquid phases with a barrier that transmits electrons. A possible solution relies on the use of a pair of structures based on Gaseous Electron Multipliers(GEMs) with misaligned holes. Rather than amplifying electron signals in gas pockets within their holes, their holes will be filled with LAr and a low biasing voltage, so that incident drifting electrons are drawn into the holes but not amplified. Instead, amplification will occur in the gas phase above the structures. Its core element is a GEM-like structure machined from polyethylene naphthalate(PEN). Since PEN scintillates in the visible spectrum, the risk of increased radioactivity due to the larger mass compared to traditional wire grids is negated by the potential to veto its own radioactivity. As such, these structures may also be a useful alternative to wire grids. In this work, we report the newest developments on the production of GEM-like structures using laser-based techniques, namely the manufacture of the first batch PEN and PMMA-based GEM-like structures. This process allows low-cost, reproducible fabrication of a high volume of such structures. In addition to being a low radioactive technique, we expect that it will allow the scaling up of the production of these structures at a reduced cost. First tests indicate good electrical stability, while the performance assessment is still ongoing.

Mattias Ergon, Peter Lundqvist, Claes Fransson et al.

We use the light curve and spectral synthesis code JEKYLL to calculate a set of macroscopically mixed Type IIb supernova (SN) models, which are compared to both previously published and new late-phase observations of SN 2020acat. The models differ in the initial mass, the radial mixing and expansion of the radioactive material, and the properties of the hydrogen envelope. The best match to the photospheric and nebular spectra and lightcurves of SN 2020acat is found for a model with an initial mass of 17 solar masses, strong radial mixing and expansion of the radioactive material, and a 0.1 solar mass hydrogen envelope with a low hydrogen mass-fraction of 0.27. The most interesting result is that strong expansion of the clumps containing radioactive material seems to be required to fit the observations of SN 2020acat both in the diffusion phase and the nebular phase. These "Ni bubbles" are expected to expand due to heating from radioactive decays, but the degree of expansion is poorly constrained. Without strong expansion there is a tension between the diffusion phase and the subsequent evolution, and models that fit the nebular phase produce a diffusion peak that is too broad. The diffusion phase lightcurve is sensitive to the expansion of the "Ni bubbles", as the resulting Swiss-cheese-like geometry decreases the effective opacity and therefore the diffusion time. This effect has not been taken into account in previous lightcurve modelling of stripped-envelope SNe, which may lead to a systematic underestimate of their ejecta masses. It should be emphasized, though, that JEKYLL is limited to a geometry that is spherically symmetric on average, and large-scale asymmetries may also play a role. The relatively high initial mass found for the progenitor of SN 2020acat places it at the upper end of the mass distribution of Type IIb SN progenitors, and a single star origin can not be excluded.

A. V. Rozhko

The implementation of targeted medical care to the population of the Republic of Belarus and Russia affected by the Chernobyl disaster is carried out within the framework of national targeted programs, as part of the Union State event «Providing comprehensive medical care to certain categories of citizens of Belarus and Russia exposed to radiation as a result of the Chernobyl disaster» based on medical centers in Russia and Belarus. The relevance of the Measure for the provision of certain types of specialized, including hightech, medical care to citizens of the Republic of Belarus exposed to radiation as a result of the disaster at the Chernobyl nuclear power plant is based on the data on morbidity. The analysis of diseases showed an increase in morbidity rates for such nosological forms as chronic renal failure, secondary and tertiary hypoparathyroidism, diseases of the retina and vitreous body, immunodeficiency states, varicose veins of the lower extremities, acute lymphoblastic leukemia and lymphomas in children. On the territory of the Republic of Belarus in 2016-2021, the provision of comprehensive medical care within the framework of the Measure was carried out at the Republican Scientific and Practical Center for Radiation Medicine and Human Ecology. In 2016-2021, on the base of the Republican Research Centre for Radiation Medicine and Human Ecology 1607 citizens of the Republic of Belarus who suffered from the Chernobyl disaster received high-tech and specialized medical care (in 2016 – 238, in 2017 – 260, in 2018 – 264, in 2019 – 264, in 2020 – 278, in 2021 – 303). The main part of medical care was provided in the surgical applications: transplantation of the kidney and parathyroid glands, surgeries on the posterior segment of the eye, reconstructive surgeries of the pelvic floor in women, laser vein correction. The successful implementation of the Measure in 2016–2021 made it possible to work out the possibility of holding the Measure of the Union State for subsequent years, specifying the amount of funding and additional volumes of comprehensive medical care for citizens in need who were exposed to radiation due to the Chernobyl disaster.

Fidéllis Bitencourt Gonzaga Louzada e Estanislau, Carlos Eduardo Velasquez, Antonella Lombardi Costa et al.

Based on the idea of adopting closed fuel cycle in current pressurized water reactors (PWR) in order to reduce the use of natural uranium and recycle the spent fuel accumulated in the world inventory, this paper aims to compare two closed nuclear fuel cycles simulated at Model for Energy Supply Strategy Alternatives and their General Environmental Impacts (MESSAGE). The nuclear fuel cycles compared are: i) a closed fuel cycle with recovering of plutonium (Pu) to fabricate the mixed oxide (MOX) fuel; ii) a closed fuel cycle with recovering of a transuranic matrix to fabricate the transuranic fuel spiked with depleted uranium (TRU-U)O2. The comparison is based on the Brazilian nuclear energy system. They consider the time frame of 2019-2060 and the introduction of Angra 3 in the system. Advantages and disadvantages of using the strategy of operating with the different nuclear fuel cycles are shown, which include results regarding natural uranium consumption, spent fuel accumulation or utilization, nuclear waste and the nuclear fuel costs for both fuels.

S. Rosswog, O. Korobkin

Compact binary mergers involving neutron stars can eject a fraction of their mass to space. Being extremely neutron rich, this material undergoes rapid neutron capture nucleosynthesis, and the resulting radioactivity powers fast, short-lived electromagnetic transients known as kilonova or macronova. Such transients are exciting probes of the most extreme physical conditions and their observation signals the enrichment of the Universe with heavy elements. Here we review our current understanding of the mass ejection mechanisms, the properties of the ejecta and the resulting radioactive transients. The first well-observed event in the aftermath of GW170817 delivered a wealth of insights, but much of today's picture of such events is still based on a patchwork of theoretical studies. Apart from summarizing the current understanding, we also point out questions where no consensus has been reached yet, and we sketch possible directions for the future research. In an appendix, we describe a publicly available heating rate library based on the WinNet nuclear reaction network, and we provide a simple fit formula to alleviate the implementation in hydrodynamic simulations.

Julien Guillot, Brigitte Roussiere, Sandrine Tusseau-Nenez et al.

Nowadays, intense exotic beams are needed in order to study nuclei with very short half-life. To increase the release efficiency of the fission products, all the target characteristics involved must be improved (e.g. chemical composition, dimensions, physicochemical properties such as grain size, porosity, density etc). In this article, we study the impact of the target thickness. Released fractions measured from graphite and uranium carbide pellets are presented as well as Monte-Carlo simulations of the Brownian motion.

Buse Gul Atli Tekgul, N. Asokan

In a data-driven world, datasets constitute a significant economic value. Dataset owners who spend time and money to collect and curate the data are incentivized to ensure that their datasets are not used in ways that they did not authorize. When such misuse occurs, dataset owners need technical mechanisms for demonstrating their ownership of the dataset in question. Dataset watermarking provides one approach for ownership demonstration which can, in turn, deter unauthorized use. In this paper, we investigate a recently proposed data provenance method, radioactive data, to assess if it can be used to demonstrate ownership of (image) datasets used to train machine learning (ML) models. The original paper reported that radioactive data is effective in white-box settings. We show that while this is true for large datasets with many classes, it is not as effective for datasets where the number of classes is low $(\leq 30)$ or the number of samples per class is low $(\leq 500)$. We also show that, counter-intuitively, the black-box verification technique is effective for all datasets used in this paper, even when white-box verification is not. Given this observation, we show that the confidence in white-box verification can be improved by using watermarked samples directly during the verification process. We also highlight the need to assess the robustness of radioactive data if it were to be used for ownership demonstration since it is an adversarial setting unlike provenance identification. Compared to dataset watermarking, ML model watermarking has been explored more extensively in recent literature. However, most of the model watermarking techniques can be defeated via model extraction. We show that radioactive data can effectively survive model extraction attacks, which raises the possibility that it can be used for ML model ownership verification robust against model extraction.

Z. Ya. Vagidova, A. V. Vodovatov, I. K. Romanovich et al.

The aim of the study was to estimate the patient effective doses from hepatic arterial chemoembolization. The study was based on the parameters of the protocols of liver chemoembolization collected for 67 patients in Angiography department of the «A.M. Granov Russian Scientific Center of Radiology and Surgical Technologies» of the Ministry of Health of the Russian Federation. The parameters were collected using a dedicated questionnaire and exported from digital image files in DICOM format with preliminary anonymization. The simulation of patient exposure was performed using PCXMC 2.0 software. The median values of the patient dose-related quantities (minimum and maximum values) were as follows: total dose–area product – 6.1 Gy×cm2 (3.4-693Gy×cm2), fluoroscopy time – 7.5 min (2.0-28.3 min), effective dose – 11.7 mSv (0.6-132 mSv). For three patients effective doses exceeded 100 mSv. In two cases, total dose-area product exceeded the control values for deterministic effects in the skin. No tissue reactions were identified for the whole patient sample.

K. A. Sednev, V. A. Nekrasov, V. S. Repin

The article proposes an empirical method for constructing a universal calibration for a scintillation gamma spectrometer, which allows determining the activity and specific activity of 137Cs with an accuracy of no more than 15% in counting samples of arbitrary density and volume in cylindrical containers with a volume of 250 ml and 500 ml. To construct calibration ratios, measurements of 137Cs sample media prepared on the basis of materials of different densities (quartz sand, plastic granules and sawdust) were performed. The calibration was carried out by preparing samples from the listed materials with a volume of 50 to 250 ml in increments of 50 ml for a 250 ml container and 100-500 ml in increments of 100 ml for a 500 ml container. Along with taking into account the volume of the counting sample, its weighing was also carried out. The result of the measurements performed for each material was the ratio of the activity of the counting sample to the counting intensity in the 137Cs window, depending on the volume. The universal calibration factor is obtained by taking into account the counting rate from the mass and volume of the sample for the corresponding measuring vessel.

Hannah E. Brinkman, J. W. den Hartogh, C. L. Doherty et al.

Radioactive nuclei were present in the early Solar System, as inferred from analysis of meteorites. Many are produced in massive stars, either during their lives or their final explosions. In the first paper in this series (Brinkman et al. 2019), we focused on the production of $^{26}$Al in massive binaries. Here, we focus on the production of another two short-lived radioactive nuclei, $^{36}$Cl and $^{41}$Ca, and the comparison to the early Solar System data. We used the MESA stellar evolution code with an extended nuclear network and computed massive (10-80 M$ _{\odot} $), rotating (with initial velocities of 150 and 300 km/s) and non-rotating single stars at solar metallicity (Z=0.014) up to the onset of core collapse. We present the wind yields for the radioactive isotopes $^{26}$Al, $^{36}$Cl, and $^{41}$Ca, and the stable isotopes $^{19}$F and $^{20}$Ne. In relation to the stable isotopes, we find that only the most massive models, $\geq$ 60M$_{\odot}$ and $\geq$ 40M$_{\odot}$ give positive $^{19}$F and $^{20}$Ne yields, respectively, depending on the initial rotation rate. In relation to the radioactive isotopes, we find that the early Solar System abundances of $^{26}$Al and $^{41}$Ca can be matched with by models with initial masses $\geq$40M$_{\odot}$, while $^{36}$Cl is matched only by our most massive models, $\geq$60M$_{\odot}$. $^{60}$Fe is not significantly produced by any wind model, as required by the observations. Therefore, massive star winds are a favoured candidate for the origin of the very short-lived $^{26}$Al, $^{36}$Cl, and $^{41}$Ca in the early Solar System.

Camila Engler, Márcia Regina Pererira Attie, Lucas Paixão Reis et al.

RESUMO Objetivo: A dose glandular média (DGM) é a grandeza dosimétrica utilizada para estimar a dose de radiação à qual um paciente é exposta ao realizar um exame de mamografia. Este estudo tem como objetivo verificar a relação entre os fatores característicos do paciente e a DGM. Materiais e Métodos: As imagens de tomossíntese mamária de 660 pacientes foram analisadas usando o software Volpara. A partir desta análise, obteve-se a densidade volumétrica da mama (DVM) e a DGM. A idade do paciente e a espessura da mama comprimida (EMC) foram obtidas do cabeçalho DICOM das imagens. Utilizando o software estatístico SPSS, foram realizados testes de correlação entre a DVM, a idade do paciente e a TCC com a DGM, e calculados os respectivos coeficientes de correlação (r). Resultados: A amostra de pacientes teve uma média da EMC de 59 ± 12mm, mediana da idade da paciente de 51 anos (25 a 87 anos), mediana da DGD de 1,53 mGy (0,43 a 4,68 mGy) e mediana da DVM de 8% ( Intervalo de 2,16% a 36,89%). Os coeficientes de correlação calculados foram 0,695 para a relação entre DGM e EMC, 0,095 para a relação entre DGM e DVM e -0,280 para a relação entre DGM e a idade da paciente. Conclusão: Os resultados mostram que a EMC é o fator mais relacionado ao aumento da DGM. DVM é o fator com menor impacto e a idade da paciente tem uma relação inversa com a DGM.  ABSTRACT Objective: Mean Glandular Dose (MGD) is the dosimetric quantity used to estimate the radiation dose to which a patient is exposed when performing a mammography examination. This study aims to verify the relationship between patient characteristic factors and MGD. Materials and Methods: Breast tomosynthesis images of 660 patients were analyzed using Volpara software. From this analysis, the volumetric breast density (VBD) and the MGD were obtained. Patient age and compressed breast thickness (CBT) were obtained from the DICOM header of the images. Using the SPSS statistical software, correlation tests were performed between the VBD, patient age and CBT with the MGD, and the respective correlation coefficients (r) were calculated. Results: The patient sample had a mean CBT of 59 (± 12mm), median patient age of 51 years (25 to 87 years range), median MGD of 1.53 mGy (0.43 to 4.68 mGy range), and median VBD of 8% (2.16% to 36.89% range). The calculated correlation coefficients were 0.695 for the relationship between MGD and CBT, 0.095 for the relationship between MGD and VBD, and -0.280 for the relationship between MGD and patient age. Conclusion: The results show that CBT is the factor most related to the MGD increase. VBD is the factor with the least impact and the patient's age has an inverse relationship with the MGD.

Fernanda Stephanie Santos

Computed Tomography (CT) has been one of the most used exam for radiologic diagnostic in medicine. The increase of CT is a global concern due to high doses of radiation. The dose evaluation in CT is one of many steps that can contribute for reducing patient doses. The head CT scans helps to diagnose disorders that affect the brain, including tumors, infarction, bleeding within the brain, hematoma and other diseases. The aim of this work is to compare the reduction of absorbed dose in the head CT scan with and without the use of bismuth shielding using a male and female anthropomorphic phantom model Alderson Rando.The head CT scan were done from the cervical vertebra C1 to the top of skull, in a GE CT scanner, LightSpeed VCT model, with 64 channels.Radiochromic films strips were used to evaluate the doses in the organs such as lenses, thyroid, hypophysis, spinal cord, pharynx, breasts, salivary and parotid glands.Record doses were lower with the use of bismuth shielding in both phantoms for all organs, mainly in the lenses. The analysis of noise in the image of the head central slice presented acceptable values for soft tissues, less than 1%. Dose values were significantly reduced and they suggested that the use of bismuth shielding would be a proper procedure for protection during a head CT scan.

Hannah Klion, Paul C. Duffell, Daniel Kasen et al.

The merger of two neutron stars produces an outflow of radioactive heavy nuclei. Within a second of merger, the central remnant is expected to also launch a relativistic jet, which shock-heats and disrupts a portion of the radioactive ejecta. Within a few hours, emission from the radioactive material gives rise to an ultraviolet, optical, and infrared transient (a kilonova). We use the endstates of a suite of 2D relativistic hydrodynamic simulations of jet-ejecta interaction as initial conditions for multi-dimensional Monte Carlo radiation transport simulations of the resulting viewing angle-dependent light curves and spectra starting at 1.5h after merger. We find that on this timescale, jet shock heating does not affect the kilonova emission. However, the jet disruption to the density structure of the ejecta does change the light curves. The jet carves a channel into the otherwise spheroidal ejecta, revealing the hot, inner regions. As seen from near ($\lesssim 30 °$) the jet axis, the kilonova is brighter by a factor of a few and bluer. The strength of this effect depends on the jet parameters, since the light curves of more heavily disrupted ejecta are more strongly affected. The light curves and spectra are also more heavily modified in the ultraviolet than in the optical.

E. Sánchez García

One of the most powerful techniques for direct detection of dark matter via elastic scattering of galactic WIMPs is the use of liquid argon time projection chambers. Atmospheric argon (AAr) has a naturally occurring radioactive isotope, \ar{}, of cosmogenic origin. The use of argon extracted from underground wells, deprived of \ar{}, is key to the physics potential of these experiments. The DarkSide-20k (DS-20k) dark matter search experiment will operate with 50 tonnes of radio-pure underground argon (UAr), extracted from the Urania plant in Cortez (USA) and purified in the Aria distillation plant (Sardinia, Italy). Assessing the radio-purity of UAr in terms of \ar{} is crucial for the success of DS-20k, as well as for future experiments of the Global Argon Dark Matter Collaboration (GADMC), and will be done with the experiment named \dia{}. DArT is a small chamber that will contain the argon under test. The detector will be immersed in the LAr active volume of the ArDM detector, located at the Canfranc Underground Laboratory (LSC) in Spain, which will act as active veto for background events coming from photons from detector materials and surrounding rock radioactivity.

Adriana Muniz de Almeida Albuquerque

The water purification procedure aims to obtain a product appropriate for human consumption, minimizing the presence of contaminants and toxic substances present in the water. Among these contaminants, some radionuclides of natural origin, such as uranium, thorium and their descendants, have been identified. Studies have shown that the stages of purification are quite effective in removing the radionuclides contained in water. The removal is due to co-precipitation of the radionuclides with the suspended materials and the precipitated material is accumulated and characterized as a Technologically Concentrated Natural Occurrence Radioactive Material (TENORM) by the United States Environmental Protection Agency (USEPA). This residue can present significant levels of radioactivity and, when discarded in the environment without any treatment, can generate a problem of environmental impact and a risk to the health of the population. In this way, some gamma emitters of the series of U, Th and the K-40 were determined in the residues generated at the Potable Water Treatment Plants – PWTPs in six municipalities of Pernambuco. The results obtain corroborate the classification of the residues generated in the PWTPs as concentrators of the radioactive components contained in the water supplied to the system and reinforce the need for the release to the environment, which is the usual way of disposal of this waste, to be carried out only after considering the radiological protection standards established.