ABSTRACT
Objective To optimize the Marinelli beaker with the simulation of Laboratory Sourceless Object Calibration Software (LabSOCS), to investigate the detection efficiency of HPGe detector in measuring noble gas, and to provide a reference for the measurement and optimization of noble gas effluent from nuclear power plants. Methods LabSOCS was used to establish a Marinelli beaker model to investigate the relationship of gamma ray detection efficiency of noble gas with gas components, gas density, size and volume of the Marinelli beaker, and the shape of source container. Results The gas components had little effect on the detection efficiency of the noble gas in the Marinelli beaker. The gas density had a relatively great effect on the detection efficiency of low-energy gamma ray. The Marinelli beaker of appropriate height and radius enabled the HPGe detector to get better measurement results. For the BE5030 HPGe detector, the highest detection efficiency of the Marinelli beakers of different volumes were observed at the location where the radius/height ratio was 0.7, and the optimal values of height and radius were given for the Marinelli beakers of different volumes. Conclusion Choosing Marinelli beaker of the appropriate size can improve the detection efficiency of noble gas in the effluent from nuclear power plants.
ABSTRACT
The aim of this study is to determine the amounts of radionuclides' activity present in samples of feed for young and adult chicken and feed for dairy and beef cattle, as well as in dicalcium phosphate (DCP) (CaHPO4), used as a nutritional supplement for animal feed. Radioactivity in these samples is due to the presence of the 238U and 232Th radioactive series, as well as their daughter. In addition, as it is for environmental samples, the activity of 40K should be an important source of radioactivity in all analyzed samples. Gamma rays were measured using a standard spectroscopy system, with a high-resolution HPGe detector. Measured activities in feed samples ranged from 0.23 to 1.51 Bq.kg-1, 0.67 to 4.21 Bq.kg-1, 0.29 to 1.63 Bq.kg-1 and 236 to 402 Bq.kg-1 for 226Ra, 228 Ra, 228 Th and 40K, respectively. Measured activities in DCP samples were 46.6 Bq.kg-1, 83 Bq.kg-1, 4.20 Bq.kg-1 and 16.61 Bq.kg-1 for 40 K, 226 Ra, 228 Ra and 228 Th, respectively. Although 40K activity has reached hundreds of Becquerel in feed samples, it should not represent a risk to human health, not even to animals, since potassium is an essential mineral to living organisms.
ABSTRACT
Objective To test a full range of processes of sample collection,preparation,measurement and analysis by conducting the intercomparison of gamma-ray spectrometry measurement and analysis of radionuclides among key laboratories,so as to facilitate the development of gamma-ray spectrometry measurement and analysis technology.Methods To complete the collection and preparation of soil samples by Chinese Center for Disease Control and Prevention (CDC) laboratory and to measure and analyze the content in two soil samples of 214Pb,214Bi,208TI,228Ac,40K and 137Cs by three laboratories using gamma-ray spectrometry.Results The value calculated by any two laboratories were less than 1 in terms of assessment standards agreed by these three laboratories and based on the activity concentrations and the total uncertainty reported from them.The measurement results from our lab were acceptable.Conclusions Measurement results from these three laboratories are in agreement to some extent.This intercomparison activity has tested the analytical ability of the three laboratories and raised the level of our laboratory in testing homogeneity of sample preparation.
ABSTRACT
The aim of this study was to examine the beryllium-7 behavior in the soil. Natural variability of beryllium-7 concentration was calculated to be about 23 percent (relative standard deviation), and the depth distribution could be approximated by an exponential decay in bare soil, with an average penetration depth in the soil about 1 cm. The nuclide was not found below 2 cm depth, which confirmed its utilization to infer the erosion processes as a tracer of soil surface. The maximum beryllium-7 concentration in the analyzed period was about 40 Bq.kg-1.
Berílio-7 é um radionuclídeo cosmogênico, com meia-vida de 53 dias, produzido pelo processo de espalação de átomos de oxigênio e nitrogênio dentro da troposfera e estratosfera. Após sua produção, este é transportado até a superfície terrestre pela deposição úmida e seca. A precipitação seca contribui somente com 3-8 por cento do inventário total. Medidas de berílio-7 no solo podem serem usadas para indicar movimento de solo da camada superficial e este estudo objetiva examinar o comportamento de berílio-7 no solo. Variabilidade natural do inventário de berílio-7 é em torno de 23 por cento (desvio padrão relativo). A distribuição em profundidade de berílio-7 pode ser aproximada por uma função exponencial no solo nu, com uma profundidade média de distribuição no solo em torno de 1 cm. O berílio-7 não foi encontrado abaixo da profundidade de 2 cm para o tipo de solo estudado, o que confirma sua utilização para avaliar processo de erosão superficial como um traçador de solo superficial. A concentração máxima de berílio-7 no período analisado é em torno de 40 Bq.kg-1.
ABSTRACT
In this study the K, U and Th radionuclide concentrations were determined in a sugar cane plantation that received large quantities of fertilizer and gypsum. Geochemical data were obtained for the clay, iron and organic matter in the soil samples, taken from depths of 0-20 and 20-40 cm. The average radionuclide concentrations were 71 Bq Kg-1 for K; 5.97 Bq Kg-1 for U, and 11.26 Bq Kg-1 for Th, and the uranium was variable (56 percent). The radionuclide average concentrations for the different fertilizer compositions varied in the range of 603.5 - 8855.0 Bq Kg-1 for K; 27.3 - 684.4 Bq Kg-1 for U, and 58 - 788.5 Bq Kg-1 for Th, and it was most variable for K (53 percent). Gypsum average concentrations were 82.6 Bq Kg-1 for K, 641.5 Bq Kg-1 for U, and 201.7 Bq Kg-1 for Th, and it was most variable for K (46 percent). Average organic matter, clay and iron concentrations for both the depths were 0.71 and 0.68 percent; 16.2 and 16.9 percent, and 29.0 and 26.8 mg/l respectively.
Determinou-se as concentrações dos radionuclídeos K, U e Th em área cultivada com cana-de-açúcar que recebe quantidades expressivas de adubos e gesso. Os radionuclídeos apresentaram teores médios de 71 Bq Kg-1 de K, 5,97 Bq Kg-1 de U e 11,26 Bq Kg-1 de Th, sendo a maior variabilidade detectada para o urânio (56 por cento). Os teores médios dos radionuclídeos para as diferentes formulações dos adubos encontram-se na faixa de 603,5 - 8855 Bq Kg-1 de K, 27,3 - 684,4 Bq Kg-1 de U e 58 - 788,5 Bq Kg-1 de Th, com maior variação para o K (53 por cento). O gesso apresentou valores médios 82,6 Bq Kg-1 de K, 641,5 Bq Kg-1 de U e 201,7 Bq Kg-1 de Th, cuja maior variabilidade também foi para o K (46 por cento). Os teores médios da matéria orgânica, argila e ferro para as duas profundidades foram respectivamente de: 0,71 e 0,68 por cento; 16,2 e 16,9 por cento; 29,0 e 26,8 mg/l.
ABSTRACT
The mate tea (Ilex paraguariensis - St. Hil.) is a beverage broadly cultivated and consumed in Brazil. The radioactive traces present in three trademarks of toasted mate tea produced at the south of Brazil were analyzed. Measurements were carried out by gamma-ray spectrometry. The average value for the 40K activity measured for marks A, B and C was 1216 ± 8, 1047 ± 14 and 666 ± 13 Bq.kg-1, respectively. The 137Cs activity was lower than the limit of detection.
Uma bebida amplamente consumida e cultivada no Brasil é o chá-mate (Ilex paraguariensis - St. Hil). Foram analisados os traços radioativos de três marcas comerciais de chá-mate tostado produzidos no sul do Brasil. As medidas foram realizadas por espectrometria gama. Os valores médios para as atividades medidas do 40K, para as marcas A, B e C foram 1216 ± 8, 1047 ± 14 e 666 ± 13 Bq.kg-1, respectivamente. As atividades para o 137Cs foram menores que o limite mínimo de detecção.