Sampling radionuclides

Location, Sample, Radionuclide, and Other Variables Concentration (Bq/kg or Bq/L) Reference ... 

The specific activity (A) of a radionuclide represents the observed counting rate in a sample. Radionuclides are useful in evaluating processes over time scales that are four to five times their half-lives, where beyond that period there is typically only 1% or less of the nuclide remaining and cannot be measured effectively (Nittrouer et al., 1984). For example, 210Pb has a half-life of 22.3 y and a useful life of approximately 112 y thus, dating sediment or rocks older that about 140 y is beyond the range of the nuclide. 

The sample radionuclide is dissolved in a liquid scintillator called the scintillation cocktail. It consists of two... 

Radionuclide identification to explain puzzling radiation measurement results or respond to clients concerning a routinely submitted sample requires the same efforts. The main distinction is that usually the sample radionuclide content and level is more narrowly defined and the response can be relatively unhurried. 

Impurities from decay products (i.e., from radioactive decay and from radiation-induced decay of chemical compounds) can interfere with the activity measurements, or with the chemical reactions employed to process the sample. Radionuclide purity is a function of time. 

Different samples of aqueous solution containing radionuclides of Co and Eu were prepared at different copper sulphate concentrations and constant polymer concentrations (pAM) of 15 mg/1. The addition of salt to the system was done to reduce both the repulsion forces between the radionuclides and the interaction between the polymeric chains [7]. The polymer efficiency for the prepared samples was determined, results are shown in Fig. 15. It is clear that the polymer efficiency for Eu " is higher than for Co. This can be explained by the difference in the tightly bound structured water associated with different cationic species [14,107]. On this basis, we expect that Co is more hydrated than Eu. This is due to the difference in the ionic size. The hydra-... 

Nuclear activation analysis (NAA) is a method for qualitatively and quantitatively detg elemental compn by means of nuclear transmutations. The method involves the irradiation or bombardment of samples with nuclear particles or high-energy electromagnetic radiation for the specific purpose of creating radioactive isotopes from the stable or naturally-occurring elements present. From the numbers, types and quantities of radioactive elements or radionuclides, it is possible to deduce information about the elemental compn of the original sample... 

Becker JS, Pickhardt C, Dietze H-J (2000) Laser ablation inductively coupled plasma mass spectrometry for the trace, ultratrace and isotope analysis of long-lived radionuclides in solid samples. Inti J Mass Spectrom 202 283-297... 

Overall, it is not possible to evaluate whether any of these factors have compromised the data included in published studies. More research is required to determine how U-and Th-series nuclides are affected by various well construction methods and sampling procedures, how reliable are data from wells not designed fro trace element monitoring, and if there are any factors that have affected the data collected from past studies. Most importantly, radionuclide studies must incorporate greater awareness of the potential problems, summarize whatever details are available regarding the wells used, and consider potential problems where the relevant information is not available. 

The most susceptible material for post-depositional loss or addition of radionuclides is the outer layer of samples that have been exposed to moisture for a long duration. Stratigraphic consistency between ages of the outermost material and that deposited prior to this provides valuable constraints on the technique. Four ages were derived for a band of clear, white calcite deposited on a stalactite from 53.6 m below sea level in a blue hole of Andros, Bahamas (Richards et al. 1994). Isotopic data for the outermost surface, which had been exposed to sea water for at least 8 ka was indistinguishable from the internal material (Fig. 8). 

Bischoff JL, Fitzpatrick JA (1991) U-series dating of impure carbonates An isochron technique using total-sample dissolution. Geochim Cosmochim Acta 55 543-554 Bonotto DM (1998) Implication of groundwater weathered profile interactions to the mobilization of radionuclides. J South Am Earth Sci 11 389-405... 

Nuclear Power Plants. EPRI (1981) conducted a survey of transuranic radionuclides in the terrestrial environs of nuclear power plant in 1978-1979. The plants included two PWRs and two BWRs that were of modem design and had been in operation at least 3 years. The 241Am levels in soil samples collected around all of the power plants were indistinguishable from fallout background. 

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