MARCIA PIRES DE CAMPOS

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Radon concentrations in a nuclear reactor center in Brazil
2021 - SILVA, PAULO S.C. da; CAMPOS, MARCIA P. de; EL HAJJ, THAMMIRIS M.; REIS, GUILHERME de L.
Radiation workers are normally exposed to doses resulting from their day-to-day activities. Besides that, background radiation, such as radon, can contribute to the exposure rates. The radionuclide 222Rn is a noble gas belonging to the uranium series, and its indoor concentration in the air depends on the exhalation from surrounding soil and the exhalation from building materials. Radon exhaling from porous building materials containing high uranium concentrations can become a significant exposure factor in areas with limited ventilation. The objective of this study was to evaluate the 222Rn concentrations in the radiochemistry and radiometric laboratories in the nuclear reactor building of the Nuclear Reactor Center (CERPq) located in the Institute of Nuclear and Energy Research (IPEN), São Paulo, Brazil. Measurements were done using a Radon Gas Monitor, model RAD7, equipped with a solid-state alpha detector. A passive method (SSNTD) was also used, consisting of square pieces of C-39 foils (2.5 cm × 2.5 cm) placed within small diffusion chambers. The CR-39 detectors were etched in KOH 30% solution at 80 °C for 5.5 h in a constant-temperature bath. After etching, the detectors were washed, dried, and scanned using a microscope to obtain the track density measurements. The activity concentrations measured with both techniques varied from 52 to 103 Bq m−3 in the studied areas of the CERPq. These values may be compared to the reference level of 100 Bq m−3 established by the World Health Organization to ensure safety environments.
Radiological implications of using phosphogypsum as building material
2020 - MAZZILLI, B.P.; CAMPOS, M.P.; NISTI, M.B.; SAUEIA, C.H.R.; MADUAR, M.F.
Phosphogypsum, a waste byproduct derived from the production of phosphoric acid, is being worldwide stock-piled, posing concerns about the environmental problems originating from this practice. Considerations about the viability of the safe reuse of this material have been raised, among them its potential use as building material. However, as phosphogypsum can contain natural radionuclides in significant concentrations, using it as a build-ing material has radiological implications, which presently prevent such application. In order to evaluate the feasibility of using phosphogypsum in the manufacturing of building elements such as bricks and plates, a com-prehensive research was undertaken in Brazil, following a multiple approach. This research included studies related to: Brazilian phosphogypsum characterization; experimental determination of radon exhalation rate; and application of theoretical models to forecast both radon exhalation and external doses in dwellers. In this paper, a comprehensive review of the research carried out in Brazil is presented.
Calibração de detectores sólidos de traços nucleares do tipo CR-39 para medidas de Rn-222 no ar
2015 - CAZULA, C.D.; CAMPOS, M.P.; MAZZILLI, B.P.
No método de detecção com detectores sólidos de traços nucleares, quando uma partícula pesada incide sobre a superfície do detector, provoca um desarranjo em sua estrutura molecular formando um traço. Uma das aplicações mais comuns desses detectores está na medição da concentração de Rn-222 no ar, um gás nobre radioativo, membro da série do U-238, emissor de partículas alfa e importante em estudos epidemiológicos para proteção dos indivíduos à radiação natural. Para determinar a concentração de Rn-222 no ar em um ambiente é necessário conhecer a densidade de traços (traços/cm2) na superfície do detector, o tempo de exposição e o fator de calibração. A determinação do fator calibração para os detectores CR-39 foi feita a partir da exposição destes a uma concentração conhecida de Rn-222. Para tanto, os detectores foram inseridos no interior de uma célula de Lucas adaptada e posteriormente expostos a uma concentração de Rn-222 de 15 kBq/m3, por meio do aparelho RN-150 da Pylon Eletronics Incorporation, que possui uma fonte de Ra-226 e libera concentrações conhecidas de Rn-222. Foram realizadas seis determinações do fator de calibração, o valor médio obtido foi de 0,0534 ± 0,0021 (traços/cm2 por Bq/m3 dia). Os resultados são compatíveis com os valores da literatura para o mesmo tipo de detector e apresentaram boa reprodutibilidade.
Phosphogypsum recycling in the building materials industry: assessment of the radon exhalation rate
2017 - CAMPOS, M.P.; COSTA, L.J.P.; NISTI, M.B.; MAZZILLI, B.P.
Phosphogypsum can be classified as a Naturally Occurring Radioactive Material (NORM) residue of the phosphate fertilizer industry. One of the main environmental concerns of its use as building material is the radon exhalation. The aim of this study is to measure the radon exhalation rate from plates and bricks manufactured with phosphogypsum from three installations of the main Brazilian producer, Vale Fertilizantes, in order to evaluate the additional health risk to dwellers. A simple and reliable accumulator method involving a PVC pipe sealed with a PVC pipe cover commercially available with CR-39 radon detector into a diffusion chamber was used for measuring radon exhalation rate from phosphogypsum made plates and bricks. The radon exhalation rate from plates varied from 0.19 ± 0.06 Bq m 2 h 1, for phosphogypsum from Bunge Fertilizers, from 1.3 ± 0.3 Bq m 2 h 1, for phosphogypsum from Ultrafertil. As for the bricks, the results ranged from 0.11 ± 0.01 Bq m 2 h 1, for phosphogypsum from Bunge Fertilizers, to 1.2 ± 0.3 Bq m 2 h 1, for phosphogypsum from Ultrafertil. The results obtained in this study for the radon exhalation rate from phosphogypsum plates and bricks are of the same order of magnitude than those from ordinary building materials. So, it can be concluded that the recycling of phosphogypsum as building material is a safe practice, since no additional health risk is expected from the radiological point of view.
Radon exposure at a radioactive waste storage facility
2014 - MANOCCHI, F.H.; CAMPOS, M.P.; DELLAMANO, J.C.; SILVA, G.S.
The Waste Management Department of Nuclear and Energy Research Institute (IPEN) is responsible for the safety management of the waste generated at all internal research centers and that of other waste producers such as industry, medical facilities, and universities in Brazil. These waste materials, after treatment, are placed in an interim storage facility. Among them are 226Ra needles used in radiotherapy, siliceous cake arising from conversion processes, and several other classes of waste from the nuclear fuel cycle, which contain Ra-226 producing 222Rn gas daughter. In order to estimate the effective dose for workers due to radon inhalation, the radon concentration at the storage facility has been assessed within this study. Radon measurements have been carried out through the passive method with solid-state nuclear track detectors (CR-39) over a period of nine months, changing detectors every month in order to determine the long-term average levels of indoor radon concentrations. The radon concentration results, covering the period from June 2012 to March 2013, varied from 0.55 ± 0.05 to 5.19 ± 0.45 kBq m−3 . The effective dose due to 222Rn inhalation was further assessed following ICRP Publication 65.
Gamma exposure due to building materials in a residential building at Peruibe, São Paulo, Brazil
2015 - CAZULA, CAMILA D.; CAMPOS, MARCIA P.; MAZZILLI, BARBARA P.
Towards a brazilian radon map: consortium radon Brazil
2014 - SILVA, N.C.; BOSSEW, P.; FERREIRA FILHO, A.L.; CAMPOS, T.F.C.; PEREIRA, A.J.S.C.; YOSHIMURA, E.M.; VEIGA, L.H.S.; CAMPOS, M.P.; ROCHA, Z.; PASCHUK, S.A.; BONOTTO, D.M.
Thoron exposure among tour guides in southern Brazilian show caves
2006 - CAMPOS, MARCIA P.; PECEQUILO, BRIGITTE R.S.; ALBERIGI, SIMONE; MAZZILLI, BARBARA P.
Natural radionuclides content and radon exhalation rate from brazilian phosphogypsum piles
2014 - NISTI, MARCELO B.; CAMPOS, MARCIA P. de; MAZZILLI, BARBARA P.
Phosphogypsum is a waste of the wet-acid process for producing phosphoric acid from phosphate rock. For every ton of phosphoric acid obtained, from the reaction of phosphate rock with sulphuric acid, about four tons of phosphogypsum are produced. The level of radioactivity present in the phosphogypsum, among other impurities, prevents its reuse for a variety of purposes. Large quantities of phosphogypsum have been produced worldwide. In 2006, the annual production was estimated to be about 170 million tons. Brazilian annual production of phosphogypsum reaches 5.5 million tons. Brazil, like other countries that produce phosphate fertilizer, tries to find solutions for the safe applications of phosphogypsum, in order to minimize the impact caused by its disposal. Most of the worldwide phosphogypsum is stockpiled, posing environmental concerns. The monitoring of air and groundwater pollution, radon exhalation rate and direct exposure to gamma radiation for workers should be considered. The aim of this study is to evaluate the natural radionuclides content and the radon exhalation rate from phosphogypsum piles from Ultrafertil and Fosfertil fertilizer industries. Samples of this material were analyzed by gamma ray spectrometry for their radionuclide content. Radon exhalation rate was measured by the activated charcoal collector method. A theoretical model for radon exhalation calculation, suggested by UNSCEAR, was applied in order to corroborate the experimental results.