Influx of radioactive gas in norm occurrences in Northeastern Brazil.

Radon and progeny are potentially relevant in radioecological studies, as they contribute more than half of the exposure to environmental radiation. The investigation of 222Rn in internal environments of municipalities of Paraíba and Rio Grande do Norte in Brazil was carried out using passive dosimetry with α Espec-222, installed in environments selected by the history of natural radiative occurrences. The monitoring time was eight months to consider seasonal influence. Concentrations from 26.91 to 316.35 Bq m-3 were obtained, with a maximum effective dose of almost 8 mSv y-1. The influence on households exceeds, by almost 31%, the average obtained for occupational environments. The municipalities of Paraíba presented higher results for Rn, with an average of almost 176 Bq m-3 and an effective dose greater than 4 mSv y-1. The application of individual occupancy factors for home and work environments made it possible to combine the dosimetric models, making the scenario closer to the real exposure of individuals who work and reside in the same municipality, with a dosimetric response of 21.45% lower than the model used worldwide. The different scenarios applied allowed expanding the radiometry of the environments, generating a database that precedes studies of environmental and radioecological impacts, strengthening security and enabling new works to interpret public health problems in search of joint and shared solutions.

α Espec-222 as a variant to the radon monitoring method using a solid state nuclear track.

Radon is important in indoor radiometry, where radiological impact is relevant. The improvement of low-cost methods makes it possible to maximize the monitored areas. Thus, a simple and robust monitoring device based on SSNTD CR-39 was designed. Detector conditions were standardized to reduce operational errors and increase productivity. The calibration factor by the slope method allowed efficiency greater than 93%. The monitoring system is satisfactory in terms of operation and performance, suitable for a wide range of radon monitoring situations.

MONITORING AND CHARACTERISATION OF NEW EVIDENCE OF NATURAL RADIONUCLIDES IN ROCK OUTCROPS IN PARAÍBA-BRAZIL.

The radiometric monitoring carried out in the present study allowed the discovery of anomalous granite outcrops in natural radionuclides in the rural area of São Mamede in the state of Paraíba, Brazil. The characterisation study made it possible to determine maximum specific concentrations of approximately 199 kBq kg-1 of 238U, 85 kBq kg-1 of 226Ra, 26 kBq kg-1 of 232Th and 24 kBq kg-1 of 40K. Models for environmental dosimetry were applied, which resulted in obtaining the following quantities: radium equivalent (Raeq), indices of external (Hex), internal (Hin) and representative (Iyr) damage, and the effective outdoor dose (HE). The maximum results presented were approximately 123 kBq kg-1, 332, 562, 832, and 68 mSv y-1, respectively. Consequently, it was possible to define the region as of high radioactive background due to isolated rocky outcrops located in the rural area of the mentioned municipality.

RADIOACTIVE DISEQUILIBRIUM AND DYNAMIC OF NATURAL RADIONUCLIDES IN SOILS IN THE STATE OF PERNAMBUCO-BRAZIL.

Environmental radioactivity studies have been allowed establishing radiometric patterns in several area of the earth's crust. The work was conducted through radiometric analyses of regions with high levels of radionuclides and others with no history of anomalies. The research allowed establishing the radiometric profile of soils in the state of Pernambuco, Brazil, using a gamma spectrometry system. The specific activities ranged from 16.5 to 287.5 Bq kg-1 for 238U, 2.0 to 191.7 Bq kg-1 for 226Ra, 1.3 to 281.4 Bq kg-1 for 232Th and from 5.0 to 2600.9 Bq kg-1 for 40K. The results showed areas with low levels of ionizing radiation. However, for 40K some points presented high values, although non-representative of the number of samples investigated. The 226Ra/238U and 232Th/238U ratios allowed to determine the radioactive imbalance condition and to obtain information about aspects of soil availability providing an assessment of the dynamics of these radionuclides.

THERMOLUMINESCENT DOSIMETRY IN THE EVALUATION OF NATURAL RADIOACTIVITY INDOOR OF HOMES NEAR THE URANIUM DEPOSIT OF PARAÍBA, BRAZIL.

High levels of primordial radionuclides have been reported in soils and rocks of São José de Espinharas, in the state of Paraiba, Brazil. These radionuclides are derived from high concentrations of natural uranium and thorium from a mine in the region. Thus, there is a need for a dosimetric evaluation in the area near the mine and the surrounding cities. In this study, the annual effective dose was analyzed in 178 points of five cities. The measurements were performed using thermoluminescent dosimetry with LiF:Mg, Ti (TLD-100). The annual effective dose from environmental exposure varied from 0.71 to 2.07 mSv, with an arithmetic mean of 0.99 mSv. This average is more than twice the estimated value for indoor environments adopted by the UNSCEAR, which is 0.41 mSv. These results will allow establishing reference values for background radiation of the region and criteria to infer a stochastic risk for the local population.

EDXRF as an alternative method for multielement analysis of tropical soils and sediments.

The quality assessment of tropical soils and sediments is still under discussion, with efforts being made on the part of governmental agencies to establish reference values. Energy dispersive X-ray fluorescence (EDXRF) is a potential analytical technique for quantifying diverse chemical elements in geological material without chemical treatment, primarily when it is performed at an appropriate metrological level. In this work, analytical curves were obtained by means of the analysis of geological reference materials (RMs), which allowed for the researchers to draw a comparison among the sources of analytical uncertainty. After having determined the quality assurance of the analytical procedure, the EDXRF method was applied to determine chemical elements in soils from the state of Pernambuco, Brazil. The regression coefficients of the analytical curves used to determine Al, Ca, Fe, K, Mg, Mn, Ni, Pb, Si, Sr, Ti, and Zn were higher than 0.99. The quality of the analytical procedure was demonstrated at a 95% confidence level, in which the estimated analytical uncertainties agreed with those from the RM's certificates of analysis. The analysis of diverse geological samples from Pernambuco indicated higher concentrations of Ni and Zn in sugarcane, with maximum values of 41 mg kg- 1 and 118 mg kg- 1, respectively, and agricultural areas (41 mg kg- 1 and 127 mg kg- 1, respectively). The trace element Sr was mainly enriched in urban soils with values of 400 mg kg- 1. According to the results, the EDXRF method was successfully implemented, providing some chemical tracers for the quality assessment of tropical soils and sediments.