Radionuclides from natural U-series in sediments from two river catchments in the UK have been studied. The aim was to gain insight into the behaviour of 238U, 234U, 230Th and 226Ra in real natural systems enriched in uranium. A radiochemical method for radium separation followed by alpha spectrometric measurement has been developed. The method allowed use of 225Ra, in equilibrium with the parent 229Th, as a yield determinant, and has been applied in 226Ra concentrations measurements in the selected areas of study.U-series progeny, 238U, 234U, 230Th and 226Ra, in totally dissolved sediments from the valley of the River Noe and the fraction leached by aqua regia, have been measured. Total sediment contents ranged from 9 ± 2 to 184 ± 8 Bq.kg-1 for uranium, 9 ± 3 to 200 ± 13 Bq.kg-1 for thorium and 18 ± 1 to 179 ± 8 Bq.kg-1 for radium. The activity concentrations in the leached fractions, compared with the total, were 46% for uranium, 54% for thorium and 56% for radium, on average. The radionuclides showed extensive disequilibrium and this suggested a complex leaching/accumulation of uranium as well as an impact of organic matter and secondary minerals.Uranium and radium have been geochemically characterised in sediments from near the South Terras abandoned uranium mine, Cornwall. Background activity concentration levels of uranium in sediments ranged from 13 ± 3 to 290 ± 14 Bq.kg-1, with radium from 42 ± 4 to 424 ± 23 Bq.kg-1. Elevated concentrations of uranium and radium were measured in two samples, S3 with 1820 ± 36 Bq.kg-1 for uranium and 940 ± 53 Bq.kg-1 for radium; and S7 with 4350 ± 53 Bq.kg-1 for uranium and 1765 ± 48 Bq.kg-1 for radium. Sequential chemical extraction for the two samples revealed that both uranium and radium were associated with organic and carbonate fractions, with 25 % of the uranium in the resistant phase of S7. 234U/238U activity ratios of the sequential extraction fractions showed different trends in the sediments, and this was linked to the impact of organic matter and/or exchange between water and sediment. Uranium-bearing minerals in association with potassium, calcium, iron, manganese and arsenic have been identified in these sediments.

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Radioisótopos de gálio são estudados e avaliados para aplicações médicas desde 1949. Nos últimos 50 anos 67Ga tem sido amplamente utilizado no diagnóstico de diversas patologias, incluindo lesões inflamatórias crônicas e agudas, bacterianas ou estéreis e diversos tipos de tumores. No Brasil 30% das clinicas que prestam serviços de Medicina Nuclear utilizam o Citrato de 67Ga com uma demanda de distribuição no IPEN-CNEN/SP de 37 GBq (1 Ci) por semana. O 67Ga apresenta meia-vida física de 3,26 dias (78 horas) e decai 100% por captura eletrônica para o 67Zn estável. Seu decaimento inclui a emissão de raios γ com energias de 93,3 keV (37%), 184,6 keV (20,4%), 300,2 keV (16,6%) e 888 keV (26%). No IPEN o 67Ga era produzido a partir da reação 68Zn(p, 2n)67Ga. Após a irradiação, o alvo era totalmente dissolvido em HCl concentrado e a solução percolada em resina catiônica DOWEX 50W-X8, 200-400 mesh, condicionada em HCl 10 mol L-1. Zinco, níquel e cobre eram eluídos em HCl 10 mol L-1 e o 67Ga em HCl 3,5 mol L-1. O produto final era obtido na forma de citrato de 67Ga. Este trabalho apresenta um método inédito, rápido, direto e eficiente de separação química e obtenção de 67GaCl3 a partir da difusão térmica (aquecimento do alvo) aliada à extração em ácido acético concentrado. A purificação foi realizada por cromatografia de troca iônica. Realizou-se a eletrodeposição do zinco natural em placas de cobre niquelado como substrato e os depósitos de zinco obtidos foram aderentes ao substrato, levemente brilhantes e uniformes. Os alvos foram irradiados com prótons de 26 MeV e corrente integrada de 10 μA.h. Após a irradiação, os alvos foram aquecidos a 300 °C por 2 horas e colocados em contato com ácido acético concentrado por 1 hora. O rendimento médio de extração de 67Ga obtido foi de (72±10)%. Esta solução foi evaporada e o resíduo foi retomado em NH4OH 0,5 mol L-1. O 67Ga foi purificado em resina catiônica Dowex 50WX8 em meio de NH4OH. A recuperação obtida foi de (98 ± 2) %, de 67Ga. O eluido foi evaporado e retomado em HCl 0,1 mol L-1. A pureza química foi verificada por ICP-OES encontrando-se (2 ± 1) μg mL -1 de zinco. As concentrações de ferro, cobre e níquel foram inferiores ao limite de detecção do método e aos limites de utilização de 67Ga. A pureza radionuclídica foi verificada por espectroscopia-γ utilizando um detector de germânio Hiper-Puro encontrando-se valor superior a (99,9%). Este método inédito permite a obtenção de 67Ga com alta pureza química, radioquímica e radionuclídica em condições de processamento menos agressivas e corrosivas que o método comumente utilizado. / Radioisotopes of gallium have been studied and evaluated for medical applications since 1949. Over the past 50 years 67Ga has been widely used in the diagnosis of various diseases, including acute and chronic inflammatory lesions, bacterial or sterile and several types of tumors. In Brazil 30% of clinics that provide services for Nuclear Medicine use 67Ga citrate and the demand for 67Ga at IPEN-CNEN/SP is 37 GBq (1 Ci)/week. The 67Ga presents physical half-life of 3.26 days (78 hours) and decays 100% by electron capture to stable 67Zn. Its decay includes the emission of γ rays with energies of 93.3 keV (37%), 184.6 keV (20.4%), 300.2 keV (16.6%) and 888 keV (26%). In the past 67Ga was produced by the reaction 68Zn (p, 2n) 67Ga at IPEN-CNEN/SP. After irradiation, the target was dissolved in concentrated HCl and the solution percolated through a cationic resin DOWEX 50W-X8, 200-400 mesh, conditioned with 10 mol L -1 HCl. Zinc, nickel and copper were eluted in 10 mol L-1 HCl and 67Ga 3.5 mol L-1 HCl. The final product was obtained as 67Ga citrate. This work presents a new, fast, direct and efficient method for the chemical separation of 67Ga by thermal diffusion (heating of the target) combined with concentrated acetic acid extraction. Purification was performed by ion exchange chromatography. Natural zinc electrodeposition was performed on nickel/copper plates as substrate and the zinc deposits were adherent to the substrate, slightly shiny and uniform. The targets were irradiated with 26 MeV protons and integrated current of 10 μA.h. After irradiation, the targets were heated at 300 °C for 2 hours and placed in contact with concentrated acetic acid for 1 hour. The average yield of extraction of 67Ga was (72 ± 10)%. This solution was evaporated and the residue was taken up in 0.5 mol L-1 NH4OH. The 67Ga was purified on cationic resin Dowex 50WX8 in NH4OH medium. The 67Ga recovery was (98 ± 2)%. This solution was evaporated and taken up in 0.1 mol L-1 HCl. The chemical purity was evaluated by ICP-OES that resulted in (2 ± 1) μg mL-1 of zinc. The concentration of iron, copper and nickel was lower than the detection limits and also than the utilization limits for 67Ga. The radionuclidic purity was greater than (99.9%). This method showed to be suitable to obtain high purity 67Ga in less aggressive chemical conditions than before.

Radioisótopos de gálio são estudados e avaliados para aplicações médicas desde 1949. Nos últimos 50 anos 67Ga tem sido amplamente utilizado no diagnóstico de diversas patologias, incluindo lesões inflamatórias crônicas e agudas, bacterianas ou estéreis e diversos tipos de tumores. No Brasil 30% das clinicas que prestam serviços de Medicina Nuclear utilizam o Citrato de 67Ga com uma demanda de distribuição no IPEN-CNEN/SP de 37 GBq (1 Ci) por semana. O 67Ga apresenta meia-vida física de 3,26 dias (78 horas) e decai 100% por captura eletrônica para o 67Zn estável. Seu decaimento inclui a emissão de raios γ com energias de 93,3 keV (37%), 184,6 keV (20,4%), 300,2 keV (16,6%) e 888 keV (26%). No IPEN o 67Ga era produzido a partir da reação 68Zn(p, 2n)67Ga. Após a irradiação, o alvo era totalmente dissolvido em HCl concentrado e a solução percolada em resina catiônica DOWEX 50W-X8, 200-400 mesh, condicionada em HCl 10 mol L-1. Zinco, níquel e cobre eram eluídos em HCl 10 mol L-1 e o 67Ga em HCl 3,5 mol L-1. O produto final era obtido na forma de citrato de 67Ga. Este trabalho apresenta um método inédito, rápido, direto e eficiente de separação química e obtenção de 67GaCl3 a partir da difusão térmica (aquecimento do alvo) aliada à extração em ácido acético concentrado. A purificação foi realizada por cromatografia de troca iônica. Realizou-se a eletrodeposição do zinco natural em placas de cobre niquelado como substrato e os depósitos de zinco obtidos foram aderentes ao substrato, levemente brilhantes e uniformes. Os alvos foram irradiados com prótons de 26 MeV e corrente integrada de 10 μA.h. Após a irradiação, os alvos foram aquecidos a 300 °C por 2 horas e colocados em contato com ácido acético concentrado por 1 hora. O rendimento médio de extração de 67Ga obtido foi de (72±10)%. Esta solução foi evaporada e o resíduo foi retomado em NH4OH 0,5 mol L-1. O 67Ga foi purificado em resina catiônica Dowex 50WX8 em meio de NH4OH. A recuperação obtida foi de (98 ± 2) %, de 67Ga. O eluido foi evaporado e retomado em HCl 0,1 mol L-1. A pureza química foi verificada por ICP-OES encontrando-se (2 ± 1) μg mL -1 de zinco. As concentrações de ferro, cobre e níquel foram inferiores ao limite de detecção do método e aos limites de utilização de 67Ga. A pureza radionuclídica foi verificada por espectroscopia-γ utilizando um detector de germânio Hiper-Puro encontrando-se valor superior a (99,9%). Este método inédito permite a obtenção de 67Ga com alta pureza química, radioquímica e radionuclídica em condições de processamento menos agressivas e corrosivas que o método comumente utilizado. / Radioisotopes of gallium have been studied and evaluated for medical applications since 1949. Over the past 50 years 67Ga has been widely used in the diagnosis of various diseases, including acute and chronic inflammatory lesions, bacterial or sterile and several types of tumors. In Brazil 30% of clinics that provide services for Nuclear Medicine use 67Ga citrate and the demand for 67Ga at IPEN-CNEN/SP is 37 GBq (1 Ci)/week. The 67Ga presents physical half-life of 3.26 days (78 hours) and decays 100% by electron capture to stable 67Zn. Its decay includes the emission of γ rays with energies of 93.3 keV (37%), 184.6 keV (20.4%), 300.2 keV (16.6%) and 888 keV (26%). In the past 67Ga was produced by the reaction 68Zn (p, 2n) 67Ga at IPEN-CNEN/SP. After irradiation, the target was dissolved in concentrated HCl and the solution percolated through a cationic resin DOWEX 50W-X8, 200-400 mesh, conditioned with 10 mol L -1 HCl. Zinc, nickel and copper were eluted in 10 mol L-1 HCl and 67Ga 3.5 mol L-1 HCl. The final product was obtained as 67Ga citrate. This work presents a new, fast, direct and efficient method for the chemical separation of 67Ga by thermal diffusion (heating of the target) combined with concentrated acetic acid extraction. Purification was performed by ion exchange chromatography. Natural zinc electrodeposition was performed on nickel/copper plates as substrate and the zinc deposits were adherent to the substrate, slightly shiny and uniform. The targets were irradiated with 26 MeV protons and integrated current of 10 μA.h. After irradiation, the targets were heated at 300 °C for 2 hours and placed in contact with concentrated acetic acid for 1 hour. The average yield of extraction of 67Ga was (72 ± 10)%. This solution was evaporated and the residue was taken up in 0.5 mol L-1 NH4OH. The 67Ga was purified on cationic resin Dowex 50WX8 in NH4OH medium. The 67Ga recovery was (98 ± 2)%. This solution was evaporated and taken up in 0.1 mol L-1 HCl. The chemical purity was evaluated by ICP-OES that resulted in (2 ± 1) μg mL-1 of zinc. The concentration of iron, copper and nickel was lower than the detection limits and also than the utilization limits for 67Ga. The radionuclidic purity was greater than (99.9%). This method showed to be suitable to obtain high purity 67Ga in less aggressive chemical conditions than before.