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Abstract  

A rapid method for the separation of 210 Po from 210 Pb was developed utilizing extraction of triisooctylamine (TIOA)/xylenein HCl+H2O2 medium. Polonium in the form of PoCl 6 2– was extracted into TIOA phase and 210Pb remains in the aqueous phase. Lead-210 was determined by -countingof its granddaughter, 210 Po ingrown from 210 Pb forsome period of time. Distribution of 210 Po and 210Pb in TIOA and aqueous phases was investigated in various concentrations ofHCl media. Hydrogen peroxide was used to further decompose organic matterand to remove sulfur to prevent its deposition on the silver disc. The improvedprocedure resulted in a good chemical yield (80–95%) and a good á-resolution.

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Abstract  

A radiochemical procedure followed by alpha spectrometry has been developed for the determination of237Np present at low activity concentrations in seawater. The analytical procedure is based on concentration of actinides from 1800 1 sea water samples by hydroxide precipitations. Neptunium is isolated by ion exchange, fluoride precipitation and extraction with TTA (thenoyltrifluoroacetone). As a radiochemical yield determinant239Np or235Np is used. Neptunium is electroplated onto stainless steel discs before alpha-spectrometry for about 10 days. The procedure allows for sequential separation of plutonium, americium, technetium and radiocaesium together with neptunium. The radiochemical yield for neptunium is only 20–50%, but the procedure has been applied with success on several samples contaminated with237Np at fallout or close to fallout levels.

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Abstract  

Silica gel suspension is electrosprayed onto the VYNS thin film to get a circular pad. The weighed -radioactive standard solution is dropped on the circle. After drying it is covered with a thin film to get a sandwich source. A new method is developed in which the -sources of high resolution and quantification are obtained. The thin film is used to avoid the contamination of -detectors used for low-level measurements.

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Abstract  

A procedure has been developed using 242Pu as tracer for simultaneous determination of 237Np and 239,240Pu in environmental samples. The validity of the method has been demonstrated by ICPMS and a-spectroscopy for up to 10 gram soil and sediment, seawater up to 200 litres. The paper describes a suitable chemical procedure for Np and Pu including a quantitative pre-concentration of neptunium and plutonium, preparation of Np4+ and Pu4+, Np(NO3)6 2- and Pu(NO3)6 2-. The ratio of 237Np/242Pu (or 237Np/239Pu) before and after the procedure has been determined using 10 g soil (free from Np and Pu) R before/R after = 1.004±3.3% (S.D n = 20) and 1 litre seawater R before/R after = 1.019±1.9% (S.D., n = 12). Results from the intercomparison samples IAEA-135, IAEA-381 and from environmental samples are presented.

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Abstract  

In nuclear reactors plutonium and transplutonium isotopes are produced by multiple neutron capture of uranium and plutonium and are important for the energy production and their composition reflects the core burnout. Under normal operation these elements are not released to the environment in significant amounts. There are accordingly very few areas or source terms where exotic transplutonium elements, such as curium isotopes, can be studied in the environment. The Chernobyl accident provided a complex spectrum of fission and activation products in fallout while the relative amounts, compared to the core inventory, of refractory elements such as transuranium and transplutonium elements were small. The major alpha-activity consisted of 242Cm (T 1/2 = 163 d) that would have decayed after a few years. In this study we have demonstrated the presence of so called supported 242Cm from the long-lived 242Amm (T 1/2 = 141 a) in environmental samples, following fallout from the Chernobyl accident. It has also been possible to assess the core burn up by using the data obtained for the Cm isotopes. The curium isotopes 243Cm (T 1/2 = 29.1 a) and 244Cm (T 1/2 = 18.1 a) cannot be resolved by conventional alpha-spectrometry. The assessment of these isotopes in environmental samples contaminated from the Chernobyl accident has been made by studying the effective half-life of the mixture of the isotopes. The data are compared with those previously obtained by high-resolution alpha-spectrometry and spectral deconvolution.

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Abstract  

The title method was successfully used for collecting239,249Pu from 200 litres of seawater by coprecipitation with 16 g FeSO4·7H2O under redcing conditions witout filtering. The plutonium is leached by concentrate HNO3+HCl from the coprecipitate and the solid particles. The precipitate is heated at 400°C and digested in aqua regia. Na2SO3 and NaNO2 have been applied to obtain the Pu4+ valence state in 0.5–1N HNO3 for different samples. Plutonium and thorium are coadsorbed on anionic resin from 8N HNO3. The column is eluted with 8N HNO3 containing fresh NaNO2 to keep the Pu4+ state for uranium decontaination. The system of the column is changed from 8N HNO3 to concentrated HCl with 50 ml concentrated HCl containing a few milligrams of NaNO2. Furtheer decontaimination of torium was achieved by elution with concentrated HCl instead of 9N HCl. The plutonium is successfully stripped by H2O, NaOH, 2N HNO3 and 0.5N HNO3 containign 0.01M NaNO3. The chemica yield of plutonium for a 2001 seawate sample is 60–80%. The resolution of the electroplated thin source is very good.

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Journal of Radioanalytical and Nuclear Chemistry
Authors:
A. Aarkrog
,
S. Boelskifte
,
H. Dahlgaard
,
S. Duniec
,
E. Holm
, and
J. Smith

Abstract  

Since the accidental loss of four nuclear weapons by a B-52 at Thule Airbase, Greenland in 1968, the marine environment at Thule has showed enhanced levels of Pu and Am. Most of the activity is confined to the benthic environment within a distance of 50 km from the crash site of the B-52. Samplings of sediments, benthos, seaplants, fish, and water have been carried out in 1968, 1970, 1974, 1979, and in 1984. The study presented herein intends to answer the following questions: What is the mean residence time of these transuranics in the benthic communities? Do Pu and Am behave differently in the environment?

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Abstract  

Distribution coefficients of technetium and ruthenium are determined under different conditions with CCl4, cyclohexanone, and 5% tri-isooctylamine (TIOA)/xylene. A method for analyzing99Tc in environmental samples has been developed by solvent extraction in which the valences of technetium and ruthenium are controlled with H2O2 and NaClO. Technetium and ruthenium which are oxidized to TcO 4 and RuO 4 by NaClO are separated by extraction with CCl4 at pH 4. The RuO 4 is reduced to low valence and technetium is kept in the TcO 4 state with H2O2. Technetium, ruthenium, and other nuclides are subsequently separated by solvent extraction with cyclohexanone and 5% TIOA/xylene. The decontamination of the procedure is 1.35·105 for103Ru and 1.66·105 for110mAg. The chemical yield of technetium-99 is 55%.

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Journal of Radioanalytical and Nuclear Chemistry
Authors:
S. Nielsen
,
A. Aarkrog
,
P. Colgan
,
E. McGee
,
H. Synnott
,
K. Johansson
,
A. Horrill
,
V. Kennedy
, and
N. Barbayiannis

Abstract  

An intercomparison of sampling procedures used by five laboratories for the determination of radiocaesium in vegetation and peaty soil was carried out at two locations in Cumbria. The multiple sampling has given information on the homogeneity of the parameters studied at each location. The parameters comprise soil bulk densities, total deposition of137Cs, deposition of137Cs in three soil layers, biomass densities, concentrations of137Cs in pasture, and activity ratios (134Cs/137Cs) in soil and vegetation. The determination of total deposition of137Cs gave no indication of differences between the laboratories. The results from the soil profiles do indicate significant differences between laboratories. One laboratory using a coring technique observed difficulties during sampling due to compression of the soil. The coring technique should thus be avoided or applied with extreme care for the sampling of depth profiles in peaty soil. The results from the sampling of pasture show no indication of differences between the laboratories. For the parameters studied the observed variabilities across soil depths and locations range from 10% to 81% in terms of relative standard deviations. A comparison across all results at the two locations indicate a 50% higher field variability at one of the sites relative to the other.

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