Wagner de Souza Pereira

Activity of natural radionuclides and their contribution to the absorbed dose in the fish cubera snapper (lutjanus cyanopterus, cuvier, 1828) on the coast of Ceara, Brazil

Visando a radioprotecao ambiental, baseada no conceito de limite de taxa de dose absorvida, foi desenvolvida uma metodologia de conversao da concentracao de atividade de radionuclideos (Bq kg-1) em taxa de dose absorvida (Gy a-1). O modelo considera apenas a taxa de dose absorvida interna. Essa metodologia foi aplicada ao peixe vermelho-caranho (Lutjanus cyanopterus, Cuvier, 1828) capturado na costa do Ceara e aos radionuclideos naturais: urânio-238, radio-226, chumbo-210, torio-232 e radio-228. As taxas de dose absorvidas foram calculadas por radionuclideo e por tipo de radiacao emitida. A taxa de dose media devida a esses radionuclideos foi de 5.36 µGy a-1, valor seis ordens de grandeza menor que o valor de limite de taxa de dose absorvida utilizada no presente trabalho (3.65 103 mGy a-1), e similar ao encontrado na literatura para peixes bentonicos. Ra-226 e U-238 contribuiram com 67% e 22% da taxa de dose absorvida, seguidos de Th-232 com 10%. Ja Ra-228 e Pb-210 respondem por menos de 1% da taxa de dose absorvida. Essa distribuicao e um pouco diferente do relatado na literatura, onde Ra-226 responde por 86% da taxa de dose absorvida.

Absorbed Dose Rate Due to Intake of Natural Radionuclides by Tilapia Fish (Tilapia nilotica,Linnaeus, 1758) Estimated Near Uranium Mining at Caetité, Bahia, Brazil

The uranium mining at Caetite (Uranium Concentrate Unit—URA) is in its operational phase. Aiming to estimate the radiological environmental impact of the URA, a monitoring program is underway. In order to preserve the biota of the deleterious effects from radiation and to act in a pro‐active way as expected from a licensing body, the present work aims to use an environmental protection methodology based on the calculation of absorbed dose rate in biota. Thus, selected target organism was the Tilapia fish (Tilapia nilotica, Linnaeus, 1758) and the radionuclides were: uranium (U‐238), thorium (Th‐232), radium (Ra‐226 and Ra‐228) and lead (Pb‐210). As, in Brazil there are no radiation exposure limits adopted for biota the value proposed by the Department of Energy (DOE) of the United States of 3.5×103 μGy y−1 has been used. The derived absorbed dose rate calculated for Tilapia was 2.51×100 μGy y−1, that is less than 0.1% of the dose limit established by DOE. The critical radionuclide was Ra‐226, with 56% of ...

The State of the Art of the World Radioprotection System

Ionizing radiation can expose individuals, and this exposure may cause deleterious biological effects. Protection against these effects, called radioprotection is accomplished through actions at the source, on the exposure routes and on the individual. It is assumed a proportional relationship between increased exposure and increased risk of stochastic effects of exposure. This approach allows dividing the network events and exposure situations and evaluating steps which are important for radioprotection. The aim of this study is to evaluate the state of the art radiation protection recommendations published by the International Commission on Radiological Protection (ICRP). For operational reasons, the radioprotection needs to perform simplifications in the relations between sources and biological effects. The last simplification was made in 2007, dividing the relations according to the sources and individuals. The principles of radioprotection (justification, dose limitation and optimization) were maintained and strengthened. The ratio depending on the source allowed the inclusion in the sources of regulatory framework previously not included and definitions of dose constraint concepts and reference levels. All this, when used with the principle of optimization of radiation protection can restrict individual doses. The maintenance of the three radiation protection principles demonstrates the robustness of these principles, as well as the maintenance of the dose limits demonstrates the confidence of the radioprotection community in the safety of these limits. Brazilian radioprotection did not reach yet the state of the art described here and is still based on ICRP previous recommendation edited in 1990, but being the legal regulations for Brazil they must be obeyed. All legislation based on ICRP No 60 and subsequent recommendations are able to protect quite adequately the environment and workers, although they are not in the state of the art as defined by the ICRP No 103 and subsequent recommendations.

Analysis of Lead-210 in Surface Water nearby a Phosphate Mining at Semi-arid Region in Santa Quitéria, Ceará State, Brazil

Aims: To report the activity concentrations (AC) of 210 Pb in surface waters in a semi-arid region, aiming to record these concentrations before the beginning of a Naturally Occurring Radioactive Material (NORM) mining operation, facilitating subsequent comparisons with the operational phase besides verifying the radioecological characteristics of this radionuclide and the potability of the water used for human consumption by the local population. Original Research Article Pereira et al.; AIR, 9(6): 1-8, 2017; Article no.AIR.33213 2 Study Design: The water samples were collected in a six points grid associated to places of human consumption, aiming to verify their radioecological characteristics and radiological potability. Place and Duration of Study: The study site was a semi-arid region associated to a NORM phosphate deposit, between October 2009 and December 2011. No collection occurred in January and February 2010, accounting for 25 collections and 50 analyzes (soluble and particulate) per point. Methodology: 1 L of water, per point, was collected acidulated and filtered. The filtrate was considered as the soluble fraction and the retained part as the particulate fraction. The Pb was separated by coprecipitation and analyzed by total beta counts. Data were analyzed by univariate and multivariate statistical methods and the values found were compared with international potability standards. Results: The values found were within the international recommendations of ingestion of 210 Pb in water (mean value of 0.05 Bq∙l < recommended of 0.1 Bq∙l). Radionuclide radioecology proved to be complex. The total AC of 210 Pb (sum of the soluble and particulate fractions) showed no difference between points, ranging from 0.05 Bq∙l -1 at point 01SQ to 0.10 Bq∙l -1 at point 04SQ. But when the AC of the fractions were analyzed, it could be verified that the AC of the particulate fraction were systematically higher than that of the soluble fraction. Conclusion: The analyzed water, in relation to the activity concentration of Pb, is considered potable and the particulate fraction has higher AC than the soluble fraction. The characterization of the water must be complemented when entering the operation of the phosphate mine to verify the radiological environmental impact assessment of the enterprise.

RADIOECOLOGIA DE RESERVATÓRIOS APLICADA À RADIOPROTEÇÃO AMBIENTAL: ESTUDO DE CASO NO BRASIL

ReseRvoiRs Radioecology applied to enviRonmental RadiopRotection: case study in bRasil. Radioecology is concerned with the study of the behaviour of radionuclides in the environment whilst the concern of environmental radioprotection is to avoid the deleterious biological effects of exposure to radiation. To achieve these goals, both sciences use environmental dispersion models and dosimetry, which are dependent on environmental transfer factors (ETF). To assess the radiological environment impact (REI) in reservoirs, a model of radionuclides dispersion in the environment was proposed based on the division of the reservoir into compartments interrelated through ETF. The International Atomic Energy Agency (IAEA) proposed ETF’s based on world averages for various radionuclides that are widely used for impact assessments of facilities handling radionuclides. This study aims to estimate local values of ETF’s, bioaccumulation factors and partition coefficient for the radionuclides 238U, 232Th, 226Ra, 228Ra and 210Pb PEREIRA, W.S. et al. Oecol. Aust., 15(3): 697-708, 2011 698 in two reservoirs. One reservoir is located in the caatinga-cerrado transition zone (southwest of Bahia state) and the other one in the tropical forest-savanna transition area (south of Minas Gerais state) and compare them with the values recommended by IAEA. Finally, the result of the dispersion model was used in dosimetric models in order to generate a REI based on dose calculation in the biota. The use of ETF’s values locally estimated and values recommended by IAEA resulted in assessments different by orders of magnitude, and the values recommended by IAEA resulted in REI an order of magnitude higher than the one obtained from locally estimated EFT’s. This fact points to the need to establish local EFT’s. The values recommended by IAEA proved to be conservative and may be used for preliminary assessments.

UTILIZATION OF FISH AS BIOLOGICAL MONITORS IN CONTINENTAL AQUATIC ECOSYSTEMS FOR ENVIRONMENTAL PROTECTION FROM RADIATION

UTILIZATION OF FISH AS BIOLOGICAL MONITORS IN CONTINENTAL AQUATIC ECOSYSTEMS FOR ENVIRONMENTAL PROTECTION FROM RADIATION. The present work revisits methodologies to evaluate radiation absorbed dose in fi sh, while presenting parameters on which a methodology for evaluating environmental radiological impact based on the amount of absorbed dose of the biota can be mounted, herein focusing on continental fi shes. This approach is recent and subsided by national and international organisations. A general review of biota dose calculation methods is given. From these data we listed formulas for calculating the conversion factors from activity concentration to dose rate, and to calculate derived water and sediment limits. Herein is also presented a new model to calculate the absorbed dose per year based on the model designed by the US Department of Energy, and a dose limit is proposed based on this model. We tried to point out new perspectives for the development of environmental radiological evaluation methods by suggesting a way of managing the absorbed dose by the biota based on the methods to quantify environmental damage.

Analysis of the Body Distribution of Absorbed Dose in the Organs of Three Species of Fish from Sepetiba Bay

The body distribution of Polonium‐210 in three fishes from the Sepetiba Bay (Macrodon ancylodon, Micropogonias furnieri and Mugil curema) has been studied under the approach of the Department of Energy of the United States of America (DOE) that set the limit of absorbed dose rate in biota equal to 3.5×103 μGy/y, and that also established the relation between dose rate (D) and radionuclide concentration (c) on a fish muscle fresh weight basis, as follows: D = 5.05 E×N×C, assuming that the radionuclide distribution is homogenous among organs. Two hypotheses were tested here, using statistical tools: 1) is the body distribution of absorbed dose homogenous among organs? and 2) is the body distribution of absorbed dose identical among studied fishes? It was concluded, as expected, that the distribution among organs is heterogeneous; but, unexpectedly, that the three fishes display identical body distribution pattern, although they belong to different trophic levels. Hence, concerning absorbed dose calculation,...