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Summary  

New, quantitative methods for the determination of actinides have been developed for application to marine environmental samples (e.g., sediment and fish). The procedures include aggressive dissolution, separation by anion-exchange resin, separation and purification by extraction chromatography (e.g., TRU, TEVA and UTEVA resins) with measurement of the radionuclides by semiconductor alpha-spectrometry (SAS). Anion-exchange has proved to be a strong tool to treat large volume samples, and extraction chromatography shows an excellent selectivity and reduction of the amounts of acids. The results of the analysis of uranium, thorium, plutonium and americium isotopes by this method in marine samples (IAEA-384, -385 and -414) provided excellent agreement with the recommended values with good chemical recoveries.

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Abstract  

Liquid scintillation spectrometry has become the most widespread method for quantitative analysis of low level -emitters in environmental samples. This technique has been applied in the measurements of 241Pu, 3H and 90Sr in seawater and sediment samples. 241Pu can be measured by direct analysis of an electrodeposited source using - discrimination or by extraction of electrodeposited plutonium into a liquid form compatible with scintillation cocktail. Sediment from Mururoa and Fangataufa atolls showed activities ranging from 18 to 44 Bq/kg. A sediment profile sampled around Bikini Atoll in 1997 showed 241Pu activities ranging from 0.3 to 30 Bq/kg. 3H activities in pore water sediment from Mururoa and Fangataufa atolls were of the order of 103 Bq/m3 which demonstrated its underground origin. 90Sr was measured in the presence of 90Y. The counting efficiency was 92.41.5% and the background 0.027±0.001 s-1. The average chemical recovery for 90Sr was 673%.

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Summary  

A Radioanalytical Emergency Procedures Manual Database (REPMD) will be an important tool to assist laboratories preparing for emergency response to a sudden release of radioactivity into the environment. The collection and systematic organization of existing sampling, screening and radioanalytical methods will enable laboratories to assess the appropriate methodologies for their use. REPMD is intended to be flexible, searchable, and interactive to accommodate a wide range of available techniques while being protected from unauthorized modifications. Website access by the world-wide scientific community will make the database a foundation for international comparison. The information in the database will also serve as a comprehensive and periodically updated source of methods and procedures suitable for training programs and rapid reference.

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Abstract  

241Pu was measured in reference materials and marine samples using a novel method based on rare earth fluoride co-precipitation followed by liquid scintillation spectrometry (LSS). Disc sources used for -spectrometry of 238Pu and 239+240Pu were leached with concentrated nitric acid before neodymium fluoride co-precipitation to scavenge plutonium in the lower oxidation states was carried out. After the determination of the chemical recovery by -spectrometry, the precipitate was recovered in a H3BO3/HNO3 based dissolver and mixed with Packard Insta-GelÒ Plus cocktail before LSS. Reasonable agreement has been obtained between the results obtained using this methods and the data obtained by direct disc analysis by LSS and ICP-MS. The 241Pu/239+240Pu ratios were coherent with the expected origin of the Pu contaminant in the marine environment showing the validity of the method.

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Abstract  

An improved and rapid method is described for the determination of 90Sr in environmental samples, through the separation of the daughter 90Y at equilibrium. The procedure is based on the HDEHP solvent extraction in combination with liquid scintillation spectrometry (LSS). A low background QuantulusÔ has been optimized for low level counting of Cerenkov radiation emitted by the hard b-emitter 90Y. The counting efficiency was 60% and the background 0.53 cpm. The reliability and reproducibility of the method have been checked using IAEA reference materials. The chemical recovery for 90Y extraction ranges from 83 to 90%.

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Abstract  

The development of radioanalytical methods for low level radionuclides in marine environmental samples is presented. In particular, emphasis is placed on the introduction of extraction chromatography (EC) as a tool for improving the quality of results as well as reducing the analysis time. However, the advantageous application of EC often depends on the effective use of suitable preconcentration techniques, such as co-precipitation, to reduce the amount of matrix components which accompany the analytes of interest. On-going investigations in this field relevant to the determination of environmental levels of actinides, 137Cs and 90Sr are discussed.

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Abstract  

Analysis of plutonium isotopes by Semiconductor Alpha Spectrometry (SAS), ICP-sector field mass spectrometry (ICP-MS) and Accelerator Mass Spectrometry (AMS) was carried out in seawater samples collected from the Northeast Atlantic Ocean (nuclear waste dumping sites) and Northwest Pacific Ocean. No particularly elevated levels of the atom ratios of 240Pu/239Pu compared to global fallout ratio (0.18) were found in the Northeast Atlantic Ocean seawater samples. The higher levels of atom ratios of 240Pu/239Pu were found in the Northwest Pacific Ocean. This is mainly due to contribution from the local fallout from nuclear weapon tests carried out at the Pacific Proving Grounds at the Marshall Islands.

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Journal of Radioanalytical and Nuclear Chemistry
Authors:
J. Torres
,
S. Olivares
,
D. De La Rosa
,
L. Lima
,
F. Martínez
,
C. Munita
, and
D. Favaro

Abstract  

Adsorption of mercury(II) and methylmercury by two tannin sorbents was investigated using radiotracers. High sorption capacities for mercury are registered for both sorbents at pH 7. ForEucaliptus Saligna Sm sorbent (ETS) the maximum sorption capacity was 1.2±0.2 mmol/g and forLysiloma latisiliqua sorbent (LTS) was 8.5±0.2 mmol/g. Methylmercury adsorption maximum was recorded at pH 4 and in buffered solutions at pH2. This species can be recovered in the presence of mercury(II). Influence of different ions present in water was examined. High recoveries were reported for ETS in tap water samples but a decrease of uptake is observed for seawater.

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Abstract  

A radiochemical procedure is described for the measurement of 0.1 Bq 237Np in a solution containing similar activity concentrations of Th, U, Pu and Am as well as activity concentrations of 60Co, 90Sr and 137Cs one hundred times higher. A tracer of 239Np (milked from 243Am) was used as an isotopic spike for chemical yield determination. The relationship between gamma-counting geometries for ampoule (liquid) and NdF3 (solid) 239Np sources was established so that Np chemical yields could be measured by a comparative method. Efficiencies of alpha-spectrometers for 237Np in NdF3 sources were measured by a bootstrap technique. Two sets of experiments were designed and used to test out the procedure.

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Abstract  

Adsorption of Cr(VI) by two tannin sorbents is evaluated using radiotracers. Evaluation of the sorption process shows that the Cr(VI)-tannin molecule binding is the principal responsible for chromium adsorption. High sorption capacities were registered for both sorbents at pH 2. ForEucaliptus Saligna Sm sorbent (ETS) sorption capacity is 0.92±0.03 mmol/g and forLysiloma latisiliqua sorbent (LTS) is 3.8±0.3 mmol/g. Influence of different ions present in water is examined. High sorption capacity is reported for LTS in sea and tap water samples. It represents 90–94% of adsorption in distillated water.

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