B. Pecequilo | Universidade de São Paulo (original) (raw)

Papers by B. Pecequilo

Research paper thumbnail of Natural radioactivity assessment by gamma spectrometry in some commercially-used granites from Paraná State, Brazil: Preliminary results

Radioprotection, 2011

Natural radioactivity concentrations in commercially-used granites from Paraná state, Brazil, wer... more Natural radioactivity concentrations in commercially-used granites from Paraná state, Brazil, were measured in order to estimate the potential radiological hazard to mankind due to granite as an ornamental building material through the 226 Ra, 232 Th and 40 K activities concentrations measured in several samples by high-resolution gamma-ray spectroscopy. Preliminary results, without considering samples selfattenuation, show activities concentrations varying from 4 ± 1 Bq kg −1 to 79 ± 3 Bq kg −1 for 226 Ra, 7 ± 1 Bq kg −1 to 142 ± 6 Bq kg −1 for 232 Th and 214 ± 14 Bq kg −1 to 1626 ± 77 Bq kg −1 for 40 K. All results are within the range of literature values for similar rocks. Further, the annual effective dose, the radium equivalent activity and the external and internal hazard indexes will be assessed.

Research paper thumbnail of Fast methodology for time counting optimization in gamma-ray spectrometry based on preset minimum detectable amounts

Journal of Radioanalytical and Nuclear Chemistry, 2009

Time counting optimization in gamma-ray spectrometry was established using four HPGe detectors an... more Time counting optimization in gamma-ray spectrometry was established using four HPGe detectors and four counting geometries. Deionized water samples with a mixed radioactive solution of 133 Ba, 134 Cs, 106 Ru, 137 Cs, 65 Zn, and 60 Co were prepared in volume from 0.1 to 3 L, and measured three times, for all detection systems, and for seven different counting times, ranging from 1,000 to 150,000 s. The obtained results were compared to the reference values from solutions with well-known activity concentrations samples, for minimum detectable amount (MDA) calculation. A counting time of 50,000 s was found to be generally sufficient to reach agreement between the preset and actual counting times.

Research paper thumbnail of Be-7 and Pb-210 deposition measured in rainfall in the city of São Paulo - Brazil

Research paper thumbnail of Activity measurements of radon from construction materials

This work presents the results of radon concentration measurements of construction materials used... more This work presents the results of radon concentration measurements of construction materials used in the Brazilian industry, such as clay (red) bricks and concrete blocks. The measurements focused on the detection of indoor radon activity during different construction stages and the analysis of radionuclides present in the construction materials. For this purpose, sealed chambers with internal dimensions of approximately 60 Â 60 Â 60 cm 3 were built within a protected and isolated laboratory environment, and stable air humidity and temperature levels were maintained. These chambers were also used for radon emanation reduction tests. The chambers were built in four major stages: (1) assembly of the walls using clay (red) bricks, concrete blocks, and mortar; (2) installation of plaster; (3) finishing of wall surface using lime; and (4) insulation of wall surface and finishing using paint. Radon measurements were performed using polycarbonate etched track detectors. By comparing the three layers applied to the masonry walls, it was concluded that only the last step (wall painting using acrylic varnish) reduced the radon emanation, by a factor of approximately 2. Samples of the construction materials (clay bricks and concrete blocks) were ground, homogenized, and subjected to gamma-ray spectrometry analysis to evaluate the activity concentrations of 226 Ra, 232 Th and 40 K. The values for the index of the activity concentration (I), radium equivalent activity (Ra eq), and external hazard index (H ext) showed that these construction materials could be used without restrictions or concern about the equivalent dose limit (1 mSv/year).

Research paper thumbnail of Committed Effective Dose from Thoron Daughters Inhalation

INTRODUCTION Mankind has been constantly exposed to radiation by natural radioactivity, nuclear t... more INTRODUCTION Mankind has been constantly exposed to radiation by natural radioactivity, nuclear tests, medical applications and nuclear energy activities. The natural radioactivity is the main component to human exposure and it is recognized that the most important contributors to the committed effective dose received by population due to natural sources are the short-lived decay products of radon (Rn) and thoron (Rn). The Earth crust contains trace quantities of U and Th which decay to Rn and Rn, respectively. In most human radon exposure studies, the contribution of thoron is usually neglected. The reason for this are: the Rn concentration is generally much lower than Rn and Rn has a relatively short half-life (55.3 s) than Rn (3.83 d). For a long time, it is well known that residents of high background areas like Brazil, China and India, where the predominant geological material is decomposed granite which has a relatively high content of Th (1), receive elevated doses, so it is ...

Research paper thumbnail of Fuel Material Analysis Using Radioactive Thermal Neutron Capture

Neutron Capture Gamma-Ray Spectroscopy, 1979

Research paper thumbnail of Tritium concentration analysis of groundwater samples from the environmental monitoring program at IPEN, São Paulo, Brazil

Radioprotection, 2005

... São Paulo: IPEN, fev. ... M. ALENCAR and MARCELO B. NISTI Ipen Environmental Monitoring Progr... more ... São Paulo: IPEN, fev. ... M. ALENCAR and MARCELO B. NISTI Ipen Environmental Monitoring Programme: Assessment of the Gamma Radiation Levels with Thermoluminescent Dosimeters, First International Meeting on Applied Physics (APHYS-2003) Badajoz, Spain, October ...

Research paper thumbnail of Dosimetric assessment from 212Pb inhalation at a thorium purification plant

Radiation protection dosimetry, 2004

At the Instituto de Pesquisas Energeticas e Nucleares (IPEN), Sao Paulo, Brazil, there is a facil... more At the Instituto de Pesquisas Energeticas e Nucleares (IPEN), Sao Paulo, Brazil, there is a facility (thorium purification plant) where materials with high thorium concentrations are manipulated. In order to estimate afterwards the lung cancer risk for the workers, the thoron daughter (212Pb) levels were assessed and the committed effective and lung committed equivalent doses for workers in place. A total of 28 air filter samples were measured by total alpha counting through the modified Kusnetz method, to determine the 212Pb concentraion. The committed effective dose and lung committed equivalent dose due to 212Pb inhalation were derived from compartmental analysis following the ICRP 66 lung compartmental model, and ICRP 67 lead metabolic model.

Research paper thumbnail of Ipen environmental monitoring programmeAssessment of the gamma radiation levels with thermoluminescence dosimeters

Recent Advances in Multidisciplinary Applied Physics, 2005

Research paper thumbnail of Thoron exposure for workers with naturally occurring radioactive materials

International Journal of Low Radiation, 2007

Research paper thumbnail of Assessment of effective doses from radon levels for tour guides at several galleries of Santana Cave, Southern Brazil, with CR-39 detectors: preliminary results

Radiation Protection Dosimetry, 2011

Cave, the most frequented cave of PETAR (High Ribeira River Tourist State Park), situated souther... more Cave, the most frequented cave of PETAR (High Ribeira River Tourist State Park), situated southern of Sao Paulo State, Brazil. The measurements were carried out with CR-39 detectors installed in four of the most frequently visited galleries. Preliminary results from November 2009 to June 2010 show radon concentrations varying from 1.9 ±0.1 kBq.m -3 to 8.4 ± 0.6 kBq.m -3 . The total effective dose for all galleries was 3.33 mSv.y -1 . The complete evaluation will be concluded by September 2010.

Research paper thumbnail of 222Rn and 212Pb exposures at a Brazilian spa

Radiation Protection Dosimetry, 2010

Termas de Araxá spa is located in Araxá, State of Minas Gerais. In this region, several minerals ... more Termas de Araxá spa is located in Araxá, State of Minas Gerais. In this region, several minerals rich in uranium and thorium are found. The mineral waters and mud from Termas de Araxá spa have been used for therapeutic and recreation purposes. In this study, the committed effective dose was evaluated for workers and patients at Araxá spa due to 222 Rn and 212 Pb inhalation. Radon measurements were carried out through the passive method with solid state nuclear track detectors (Makrofol E) over a period of 21 months, with results varying from 258 + + + + + 20 to 1634 + + + + + 111 Bq m 23 . The 212 Pb air concentration was assessed through the modified Kusnetz's method, the results varying from 0.3 + + + + + 0.1 to 2.1 + + + + + 0.2 Bq m 23 . Doses received by the spa workers are below 20 mSv . y 21 , suggested by ICRP 60 as an annual effective dose limit for occupational exposure. The radiation doses for the patients are below the mean annual effective dose due to natural sources estimated to be 2.4 mSv . y 21 .

Research paper thumbnail of Correlation of natural and artificial radionuclides in soils with pedological, climatological and geographic parameters

Journal of Radioanalytical and Nuclear Chemistry Articles, 1994

Various types of soil samples were collected in the southern part of Brazil, with depth intervals... more Various types of soil samples were collected in the southern part of Brazil, with depth intervals of 5 cm, down to 50 cm, using a specially designed sampler. Pedologieal analysis of these soils were performed. Nuclear activities of t~Cs (expressed in Bq m "2) and radioactive natural element ('X~Ra, ~Ra and '~K) eoncentrations were determined by low background gamma-ray spectrometry, l~Cs concentrations were correlated with radioactive naturat element concentrations anti pedological, climatological and geographic parameters related to the soil samples collected,

Research paper thumbnail of Fast methodology for time counting optimization in gamma-ray spectrometry based on preset minimum detectable amounts

Journal of Radioanalytical and Nuclear Chemistry, 2009

Time counting optimization in gamma-ray spectrometry was established using four HPGe detectors an... more Time counting optimization in gamma-ray spectrometry was established using four HPGe detectors and four counting geometries. Deionized water samples with a mixed radioactive solution of 133 Ba, 134 Cs, 106 Ru, 137 Cs, 65 Zn, and 60 Co were prepared in volume from 0.1 to 3 L, and measured three times, for all detection systems, and for seven different counting times, ranging from 1,000 to 150,000 s. The obtained results were compared to the reference values from solutions with well-known activity concentrations samples, for minimum detectable amount (MDA) calculation. A counting time of 50,000 s was found to be generally sufficient to reach agreement between the preset and actual counting times.

Research paper thumbnail of Natural radioactivity assessment by gamma spectrometry in some commercially-used granites from Paraná State, Brazil: Preliminary results

Radioprotection, 2011

Natural radioactivity concentrations in commercially-used granites from Paraná state, Brazil, wer... more Natural radioactivity concentrations in commercially-used granites from Paraná state, Brazil, were measured in order to estimate the potential radiological hazard to mankind due to granite as an ornamental building material through the 226 Ra, 232 Th and 40 K activities concentrations measured in several samples by high-resolution gamma-ray spectroscopy. Preliminary results, without considering samples selfattenuation, show activities concentrations varying from 4 ± 1 Bq kg −1 to 79 ± 3 Bq kg −1 for 226 Ra, 7 ± 1 Bq kg −1 to 142 ± 6 Bq kg −1 for 232 Th and 214 ± 14 Bq kg −1 to 1626 ± 77 Bq kg −1 for 40 K. All results are within the range of literature values for similar rocks. Further, the annual effective dose, the radium equivalent activity and the external and internal hazard indexes will be assessed.

Research paper thumbnail of Fast methodology for time counting optimization in gamma-ray spectrometry based on preset minimum detectable amounts

Journal of Radioanalytical and Nuclear Chemistry, 2009

Time counting optimization in gamma-ray spectrometry was established using four HPGe detectors an... more Time counting optimization in gamma-ray spectrometry was established using four HPGe detectors and four counting geometries. Deionized water samples with a mixed radioactive solution of 133 Ba, 134 Cs, 106 Ru, 137 Cs, 65 Zn, and 60 Co were prepared in volume from 0.1 to 3 L, and measured three times, for all detection systems, and for seven different counting times, ranging from 1,000 to 150,000 s. The obtained results were compared to the reference values from solutions with well-known activity concentrations samples, for minimum detectable amount (MDA) calculation. A counting time of 50,000 s was found to be generally sufficient to reach agreement between the preset and actual counting times.

Research paper thumbnail of Be-7 and Pb-210 deposition measured in rainfall in the city of São Paulo - Brazil

Research paper thumbnail of Activity measurements of radon from construction materials

This work presents the results of radon concentration measurements of construction materials used... more This work presents the results of radon concentration measurements of construction materials used in the Brazilian industry, such as clay (red) bricks and concrete blocks. The measurements focused on the detection of indoor radon activity during different construction stages and the analysis of radionuclides present in the construction materials. For this purpose, sealed chambers with internal dimensions of approximately 60 Â 60 Â 60 cm 3 were built within a protected and isolated laboratory environment, and stable air humidity and temperature levels were maintained. These chambers were also used for radon emanation reduction tests. The chambers were built in four major stages: (1) assembly of the walls using clay (red) bricks, concrete blocks, and mortar; (2) installation of plaster; (3) finishing of wall surface using lime; and (4) insulation of wall surface and finishing using paint. Radon measurements were performed using polycarbonate etched track detectors. By comparing the three layers applied to the masonry walls, it was concluded that only the last step (wall painting using acrylic varnish) reduced the radon emanation, by a factor of approximately 2. Samples of the construction materials (clay bricks and concrete blocks) were ground, homogenized, and subjected to gamma-ray spectrometry analysis to evaluate the activity concentrations of 226 Ra, 232 Th and 40 K. The values for the index of the activity concentration (I), radium equivalent activity (Ra eq), and external hazard index (H ext) showed that these construction materials could be used without restrictions or concern about the equivalent dose limit (1 mSv/year).

Research paper thumbnail of Committed Effective Dose from Thoron Daughters Inhalation

INTRODUCTION Mankind has been constantly exposed to radiation by natural radioactivity, nuclear t... more INTRODUCTION Mankind has been constantly exposed to radiation by natural radioactivity, nuclear tests, medical applications and nuclear energy activities. The natural radioactivity is the main component to human exposure and it is recognized that the most important contributors to the committed effective dose received by population due to natural sources are the short-lived decay products of radon (Rn) and thoron (Rn). The Earth crust contains trace quantities of U and Th which decay to Rn and Rn, respectively. In most human radon exposure studies, the contribution of thoron is usually neglected. The reason for this are: the Rn concentration is generally much lower than Rn and Rn has a relatively short half-life (55.3 s) than Rn (3.83 d). For a long time, it is well known that residents of high background areas like Brazil, China and India, where the predominant geological material is decomposed granite which has a relatively high content of Th (1), receive elevated doses, so it is ...

Research paper thumbnail of Fuel Material Analysis Using Radioactive Thermal Neutron Capture

Neutron Capture Gamma-Ray Spectroscopy, 1979

Research paper thumbnail of Tritium concentration analysis of groundwater samples from the environmental monitoring program at IPEN, São Paulo, Brazil

Radioprotection, 2005

... São Paulo: IPEN, fev. ... M. ALENCAR and MARCELO B. NISTI Ipen Environmental Monitoring Progr... more ... São Paulo: IPEN, fev. ... M. ALENCAR and MARCELO B. NISTI Ipen Environmental Monitoring Programme: Assessment of the Gamma Radiation Levels with Thermoluminescent Dosimeters, First International Meeting on Applied Physics (APHYS-2003) Badajoz, Spain, October ...

Research paper thumbnail of Dosimetric assessment from 212Pb inhalation at a thorium purification plant

Radiation protection dosimetry, 2004

At the Instituto de Pesquisas Energeticas e Nucleares (IPEN), Sao Paulo, Brazil, there is a facil... more At the Instituto de Pesquisas Energeticas e Nucleares (IPEN), Sao Paulo, Brazil, there is a facility (thorium purification plant) where materials with high thorium concentrations are manipulated. In order to estimate afterwards the lung cancer risk for the workers, the thoron daughter (212Pb) levels were assessed and the committed effective and lung committed equivalent doses for workers in place. A total of 28 air filter samples were measured by total alpha counting through the modified Kusnetz method, to determine the 212Pb concentraion. The committed effective dose and lung committed equivalent dose due to 212Pb inhalation were derived from compartmental analysis following the ICRP 66 lung compartmental model, and ICRP 67 lead metabolic model.

Research paper thumbnail of Ipen environmental monitoring programmeAssessment of the gamma radiation levels with thermoluminescence dosimeters

Recent Advances in Multidisciplinary Applied Physics, 2005

Research paper thumbnail of Thoron exposure for workers with naturally occurring radioactive materials

International Journal of Low Radiation, 2007

Research paper thumbnail of Assessment of effective doses from radon levels for tour guides at several galleries of Santana Cave, Southern Brazil, with CR-39 detectors: preliminary results

Radiation Protection Dosimetry, 2011

Cave, the most frequented cave of PETAR (High Ribeira River Tourist State Park), situated souther... more Cave, the most frequented cave of PETAR (High Ribeira River Tourist State Park), situated southern of Sao Paulo State, Brazil. The measurements were carried out with CR-39 detectors installed in four of the most frequently visited galleries. Preliminary results from November 2009 to June 2010 show radon concentrations varying from 1.9 ±0.1 kBq.m -3 to 8.4 ± 0.6 kBq.m -3 . The total effective dose for all galleries was 3.33 mSv.y -1 . The complete evaluation will be concluded by September 2010.

Research paper thumbnail of 222Rn and 212Pb exposures at a Brazilian spa

Radiation Protection Dosimetry, 2010

Termas de Araxá spa is located in Araxá, State of Minas Gerais. In this region, several minerals ... more Termas de Araxá spa is located in Araxá, State of Minas Gerais. In this region, several minerals rich in uranium and thorium are found. The mineral waters and mud from Termas de Araxá spa have been used for therapeutic and recreation purposes. In this study, the committed effective dose was evaluated for workers and patients at Araxá spa due to 222 Rn and 212 Pb inhalation. Radon measurements were carried out through the passive method with solid state nuclear track detectors (Makrofol E) over a period of 21 months, with results varying from 258 + + + + + 20 to 1634 + + + + + 111 Bq m 23 . The 212 Pb air concentration was assessed through the modified Kusnetz's method, the results varying from 0.3 + + + + + 0.1 to 2.1 + + + + + 0.2 Bq m 23 . Doses received by the spa workers are below 20 mSv . y 21 , suggested by ICRP 60 as an annual effective dose limit for occupational exposure. The radiation doses for the patients are below the mean annual effective dose due to natural sources estimated to be 2.4 mSv . y 21 .

Research paper thumbnail of Correlation of natural and artificial radionuclides in soils with pedological, climatological and geographic parameters

Journal of Radioanalytical and Nuclear Chemistry Articles, 1994

Various types of soil samples were collected in the southern part of Brazil, with depth intervals... more Various types of soil samples were collected in the southern part of Brazil, with depth intervals of 5 cm, down to 50 cm, using a specially designed sampler. Pedologieal analysis of these soils were performed. Nuclear activities of t~Cs (expressed in Bq m "2) and radioactive natural element ('X~Ra, ~Ra and '~K) eoncentrations were determined by low background gamma-ray spectrometry, l~Cs concentrations were correlated with radioactive naturat element concentrations anti pedological, climatological and geographic parameters related to the soil samples collected,

Research paper thumbnail of Fast methodology for time counting optimization in gamma-ray spectrometry based on preset minimum detectable amounts

Journal of Radioanalytical and Nuclear Chemistry, 2009

Time counting optimization in gamma-ray spectrometry was established using four HPGe detectors an... more Time counting optimization in gamma-ray spectrometry was established using four HPGe detectors and four counting geometries. Deionized water samples with a mixed radioactive solution of 133 Ba, 134 Cs, 106 Ru, 137 Cs, 65 Zn, and 60 Co were prepared in volume from 0.1 to 3 L, and measured three times, for all detection systems, and for seven different counting times, ranging from 1,000 to 150,000 s. The obtained results were compared to the reference values from solutions with well-known activity concentrations samples, for minimum detectable amount (MDA) calculation. A counting time of 50,000 s was found to be generally sufficient to reach agreement between the preset and actual counting times.