Romilton dos Santos Amaral

Analysis of the 40K levels in soil using gamma spectrometry

Potassium-40 was determined in soil in an area with 40,000 m2 situated in the western State of Pernambuco, Brazil. For radiometric measurements, the gamma spectrometry method with a high purity germanium (HPGe) detector was used. Sampling of 78 soil samples has been performed at intervals of 25 m. The specific activities of 40K were calculated based on the photopeak of 1.46 MeV. Values from 541 to 3,572 Bq kg-1 were obtained (mean of 1,827 Bq kg-1). These values allowed the determination of the elemental concentrations as well as the absorbed dose rates in air, 1 m above the ground. The values varied from 1.7 to 11.5% (mean of 6%) and from 23.4 to 154.3 nGy h-1 (mean of 79 nGy h-1), respectively.

Rare-earth elements in uranium deposits in the municipality of Pedra, Pernambuco, Brazil

In the present study, soil and rock samples were collected from uranium deposits in the city of Pedra, Pernambuco, Brazil. These samples were analyzed using neutron activation analysis to identify the occurrence of rare-earth elements (REE). The most abundant elements found were Ce, Nd and La, with concentrations 12 times higher than the average in the earth’s crust and 4.6 times higher than values reported in worldwide studies, including Brazil. Nonetheless, further studies to examine the economic feasibility of mining REEs from this site are necessary.

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.

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 earths 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.

ENVIRONMENTAL IONIZING RADIATION DOSE OUTDOOR IN AN INHABITED AREA WITH A HIGH CONCENTRATION OF URANO-PHOSPHATE IN NORTHEAST OF BRAZIL

A marine phosphorus region with high concentrations of phosphate, coastwise of Pernambuco, Northeast of Brazil, is densely inhabited. Rock phosphate deposits naturally contain uranium ore that produces ionizing radiation from it and its natural descendants, furthermore, its thorium and potassium concentrations are comparable to those usually found in soils. Radiological monitoring of this environment is important to verify the occurrence of harmful effective doses for the adjacent population. This study aimed at the in situ radiometric monitoring in four cities of the north of the Metropolitan Region of Recife-Pernambuco, estimating the effective environmental dose to which the local population is subject. In total, 91 points were monitored with a discriminator-type detector. The outdoor environmental effective dose rates ranged from 1.99 ± 0.09 to 7.59 ± 0.36 mSv y-1, with an average of 2.60 ± 0.69 mSv y-1.

Natural radionuclides in electronic waste: an initial approach

ABSTRACT Some radionuclides are present in trace amount in the raw material of electronic devices that suffer obsolescence and are improperly disposed of. Obsolete personal computers become electronic waste and may contain potential environmental contaminants. Furthermore, there may be an additional concern: the ionizing radiation emission. This study aimed to assess qualitatively the possibility of alpha and beta particles and gamma rays reaching somehow workers involved in the handling of such wastes. Using gamma spectrometry method, we analyzed a set of 10 microprocessors randomly taken from motherboards incorrectly discarded. The analysis resulted in the occurrence of primordial radioisotopes in the microchips.