Precise determination of the intensity of 226Ra alpha decay to the 186 keV excited state

There is a significant discrepancy in the reported values for the emission probability of the 186 keV gamma-ray resulting from the alpha decay of ²²⁶ Ra to 186 keV excited state of ²²² Rn. Published values fall in the range of 3.28 to 3.59 gamma-rays per 100 alpha-decays. An interesting observation is that the lower value, 3.28, is based on measuring the 186 keV gamma-ray intensity relative to the ²²⁶ Ra alpha-branch to the 186 keV level. The higher values, which are close to 3.59, are based on measuring the gamma-ray intensity from mass standards of ²²⁶ Ra that are traceable to the mass standards prepared by HÓNIGSCHMID in the early 1930's. This discrepancy was resolved in this work by carefully measuring the ²²⁶ Ra alpha-branch intensities, then applying the theoretical E2 multipolarity internal conversion coefficient of 0.692±0.007 to calculate the 186 keV gamma-ray emission probability. The measured value for the alpha branch to the 186 keV excited state was (6.16±0.03)%, which gives a 186 keV gamma-ray emission probability of (3.64±0.04)%. This value is in excellent agreement with the most recently reported 186 keV gamma-ray emission probabilities determined using ²²⁶ Ra mass standards.     

Validation of the quantification of natural radionuclides in raw materials and by-products using gamma-ray spectrometry

The validation of a method for the indirect quantification for ²³⁸U, ²²⁶Ra, and ²³²Th activity and the direct quantification for ⁴⁰K activity using gamma-ray spectrometry was performed in view of consistency, reliability, and accuracy of the results. The gas tightness of Al containers used to confine the radon gas was verified from the establishment of the secular equilibrium between ²²⁶Ra and its indicator. To evaluate validation parameters such as linearity, range, and accuracy, it was important to verify the equilibrium state of the reference materials (RM) for U and Th, because the ingrowth of progenies in the uranium decay series can affect the quantification of ²²⁶Ra activity even if based on a certified reference material (CRM), while the ingrowth of ²²⁸Ra from the thorium decay series should be secured in order to use ²²⁸Ac as an indicator of ²³²Th. In addition, the ruggedness of the method regarding different materials was checked using two kinds of CRM, namely bauxite as an example of a raw material and coal fly ash as a by-product.     

Growth and decay tables for radium-225 and actinium-225

To facilitate the use of²²⁵Ra as a yield tracer in radiochemical assays of²²⁶Ra and²²⁸Ra, growth and decay tables for²²⁵Ra, and its daughter²²⁵Ac, have been computed.     

Gamma ray emission intensities of226Ra in equilibrium with its daughter products

A²²⁶ Ra source of known disintegration rate has been measured to determine the absolute -ray emission intensities of members of its decay chain in radioactive equilibrium. The results are compared with other values from the literature.     

Using the 186-keV peak for 226Ra activity concentration determination in Hungarian coal-slag samples by gamma-ray spectroscopy

The uranium isotopic abundance and the ²³⁸U–²²⁶Ra secular equilibrium were determined in nine Hungarian coal slag samples. The ²²⁶Ra activity concentration was measured based on the radon decay products and also the ²²⁶Ra peak at 186 keV. Secular equilibrium existed in eight samples, whereas one sample showed a slight disequilibrium. The direct and fast measurement using only the 186 keV peak was validated which can be used after measuring the uranium isotopic ratio and verifying the ²³⁸U–²²⁶Ra secular equilibrium. This method can be used to measure the ²²⁶Ra content of high number of samples from the same geochemical background.     

The determination of radium-226 and radium-228 in soils and plants,using radium-225 as a yield tracer

Recovery of²²⁶Ra in analysis is determined using²²⁵Ra separated by anion exchange from²²⁹Th and²³³U. Radium is coprecipitated with barium, and purified by ion exchange.²²⁶Ra and²¹⁷At (decay product of²²⁵Ra) are measured by α-spectrometry.²²⁸Ra is determined both by β-counting²²⁸Ac and²²⁵Ac separated from²²⁸Ra and²²⁵Ra, and by α-counting its daughters after the decay of²²⁵Ra. Sources for α-spectrometry are prepared by electrodeposition (molecular plating).     

Implementation of a Sequential Injection Pre-Treatment Method for Simultaneous Radium and Strontium Determination

A semi-automatic procedure for the simultaneous determination of Ra and Sr in two steps has been developed. In the first step, separation and pre-concentration of both analytes is performed by using a sequential injection procedure. In the second step, the activities of ²²⁶Ra and ⁹⁰Sr, alpha and beta emitters, respectively, are determined using a low background proportional counter at the corresponding plateau potentials. ²²⁶Ra concentration is obtained by a single measurement of the precipitate. ⁹⁰Sr activity is determined by means of its daughter ⁹⁰Y carrying out two different measurements along the first day after the separation process; the solution of the Bateman radioactivity decay equations allows to obtain the initial ⁹⁰Sr-⁹⁰Y activities. The activities analysed in the present work have been ranged between 0-14 Bq/L for ²²⁶Ra and 0-175 Bq/L for ⁹⁰Sr.     

Natural radioactivity levels in mineral,therapeutic and spring waters in Tunisia

Radioactivity measurements were carried out in 26 groundwater samples from Tunisia. Activity concentrations of uranium were studied by radiochemical separation procedures followed by alpha spectrometry and that for radium isotopes by gamma-ray spectrometry.The results show that, the concentrations in water samples range from 1.2 to 69 mBq/L.1, 1.3 to 153.4 mBq/L, 2.0 to 1630.0 mBq/L and 2.0 to 1032.0 mBq/L for ²³⁸U, ²³⁴U, ²²⁶Ra and ²²⁸Ra, respectively. The U and Ra activity concentrations are low and similar to those published for other regions in the world. The natural radioactivity levels in the investigated samples are generally increased from mineral waters through therapeutic to the spring waters.The results show that a correlation between total dissolved solids (TDS) values and the ²²⁶Ra concentrations was found to be high indicating that ²⁶⁶Ra has a high affinity towards the majority of mineral elements dissolved in these waters. High correlation coefficients were also observed between ²²⁶Ra content and chloride ions for Cl^?–Na⁺ water types. This can be explained by the fact that radium forms a complex with chloride and in this form is more soluble.The isotopic ratio of ²³⁴U/²³⁸U and ²²⁶Ra/²³⁴U varies in the range from 0.8 to 2.6 and 0.6 to 360.8, respectively, in all investigated waters, which means that there is no radioactive equilibrium between the two members of the ²³⁸U series. The fractionation of isotopes of a given element may occur because of preferential leaching of one, or by the direct action of recoil during radioactive decay.The annual effective doses due to ingestion of the mineral waters have been estimated to be well below the 0.1 mSv/y reference dose level.     

An accurate method for the determination of <Superscript>226</Superscript>Ra activity concentrations in soil

A quantitative method to determine the activity concentration of ²²⁶Ra in soil samples was established using high performance environmental gamma-ray spectrometry. In this method, a semi-empirical calibration procedure was developed for full energy peak efficiency calculation utilizing the elemental composition of the soil sample. Aatami software was used to deconvolute the ²³⁵U and ²²⁶Ra doublet at 185.7 keV and 186.2 keV, respectively, and to fit the baseline of the soil gamma-spectrum for the determination of ²²⁶Ra activity. The results indicated that the Aatami doublet deconvolution procedure provides a rapid and accurate analysis of a complicated spectrum in comparison with other cumbersome spectral interference correction methods. The study also compared the results with those obtained by radon progeny (²¹⁴Pb, or ²¹⁴Bi) measurements and found that the deconvolution method provided a more accurate ²²⁶Ra activity as it is independent of the error caused by radon diffusion. This error can be quite large since the amount of escaped radon gas through the sample container walls and sealing cannot be accurately quantified.     

222Rn and 226Ra activity concentrations in groundwaters of southern Poland: new data and selected genetic relations

Since 2008, the authors have been conducting research into ²²²Rn and ²²⁶Ra activity concentrations in shallow circulation groundwaters in southern Poland. Measurements have been performed with a liquid-scintillation method and ultra low-level liquid-scintillation spectrometers α/β Quantulus 1220. The research carried out so far has demonstrated that in the Sudetes groundwaters with high activity concentrations of ²²²Rn and ²²⁶Ra are common. In other studied areas in southern Poland no shallow circulation groundwaters with high radon or radium concentrations have been found yet. The conducted research has demonstrated that the activity concentration of ²²²Rn dissolved in shallow circulation groundwaters in the Sudetes depends chiefly on the amount of radon, which after being released as gas from reservoir rocks is dissolved in waters flowing through these rocks. At the same time, the concentration of ²²²Rn dissolved in some shallow circulation groundwaters in the Carpathians is influenced significantly by the amount of radon produced from the decay of its parent ion ²²⁶Ra²⁺ dissolved in these waters.     

Application of a Liquid Scintillation Technique to the Measurement of 226Ra and 224Ra in Samples Affected by Non-Nuclear Industry Wastes

Experiment procedures have been developed for the determination of ²²⁶Ra and ²²⁴Ra activity concentration in solid and liquid samples collected around a non-nuclear industrial area, by liquid scintillation counting. The different radiochemical procedures developed in this work, have been adaptations of a radiochemical procedure previously used, for ²²⁶Ra and ²²⁴Ra determinations by LSC in drinking water, which was improved, refined up and adapted to the type of sample to be applied. These improved radiochemical methods have been applied to waste samples (phosphogypsum) produced by two factories which are engaged in phosphoric acid production, and to waters collected from the Odiel river, where during the sampling period a fraction of these wastes were released. ²²⁶Ra activity concentrations in the phosphogypsum ranged from 673 to 1178 Bq/kg dry weight, indicating that the wastes are particularly enriched in this radionuclide. Consequently, high ²²⁶Ra levels were easily found in the river waters analysed, especially in the neighbouring zones of the waste discharges.     

Anthropogenic source assessment of <Superscript>226</Superscript>Ra and <Superscript>210</Superscript>Pb in a sediment core from the Cubatão River estuary (SE Brazil)

A sediment core from an estuarine area receiving drainage from the highly industrialized Cubatão River basin (SE Brazil) showed ²²⁶Ra and ²¹⁰Pb activities up to 80 and 213 Bq kg^?1, respectively, which are greater than activities considered as regional background levels. Radionuclides and the elevated phosphorus concentrations (up to 0.3% sediment dry weight) found along the sediment core were significantly correlated with each other, indicating source similarity. These results indicate that ²²⁶Ra and ²¹⁰Pb activities are affected by fertilizer industry-derived inputs in addition to natural sources. This interpretation was supported by ²¹⁰Pb/²²⁶Ra ratios (found to be between 2.6 and 3.9) that indicate disequilibrium between ²²⁶Ra and its decay product ²¹⁰Pb, as expected for phosphogypsum-affected sediments.     

Radium isotopes in suspended matter in an estuarine system in the southwest of Spain

The presence of²²⁶Ra and²²⁴Ra in suspended matter from an estuarine system which surrounds a phosphate fertilizer complex has been investigated. The results have confirmed an important radioactive impact from the industrial complex, since up to 2.5 Bq²²⁶Ra/g suspended matter (dry) has been measured. The influence of tides and seasonal conditions, through changes in salinity, has been found to be relevant. The distribution coefficients for²²⁶Ra between the suspended matter and the river water have been calculated. The values are in agreement by order of magnitude with those found in the literature, but they clearly depend on tidal state and seasonal conditions.     

Radium accumulation in animal thyroid glands a possible method for uranium and thorium prospecting

A method of prospecting for uranium and thorium is proposed based on uptake of their radioactive daughters²²⁶Ra and²²⁸Ra by plants, the collection of plant material by herbivores, the concentration of the radioactive species by specific animal tissues, and the subsequent gamma-ray analysis of the tissues. This paper is based on work performed under United States Energy Research and Development Administration (formerly U.S.A.E.C.), Contract EY-76-C-06-1830.     

Radium isotope determination by alpha-spectrometry after electrodeposition from solution with added platinum

A method for measuring radium activity using electrodeposition onto stainless steel from solutions to which platinum ions have been added was developed. This gave high recovery with reduced electroplating times, and yielded deposits giving alpha-spectra of high resolution. Retention of the decay products in the deposit allows inference of some Ra isotopes from measurement of the activities of the high energy Po daughters. Application of the method to determination of²²⁶Ra in a marine manganese deposit is described.     

Chemometry of the distribution and origin of 226Ra, 228Ra, 40K and 137Cs in the soil near the lignite fired plants of West Macedonia (Greece)

The distribution and origin of natural ⁴⁰K,²²⁶Ra and²²⁸Ra and artificial ¹³⁷Cs have been investigated in the surface soil of a West Macedonia basin at four lignite fired power plants. No significant increase in specific activity of soil due to natural radionuclides of coal has been found. The specific activities of ²²⁶Ra, ²²⁸Ra and ⁴⁰K are equal to those of Greek soils. Radiocesium activity is slightly higher in the first 10 cm layer. The application of chemometrical methods confirmed that the radionulides ²²⁶Ra, ²²⁸Ra and ⁴⁰K are natural components of the soil and they do not originate from fly ash. This revised version was published online in July 2006 with corrections to the Cover Date.     

Über die Messung geringer Mengen Radium und Radon

Zusammenfassung Zur Messung geringer²²⁶Radium- und²²²Radongehalte werden auch auf dem Gebiet der Strahlenhygiene verschiedene Verfahren verwendet. Eine zylindrische Szintillationskammer günstigster Abmessungen bietet die Möglichkeit, Personen, die²²⁶Ra inkorporiert haben, ohne vorhergehende Anreicherung des Atem-Radons zu kontrollieren sowie Lebensmittel und andere Proben von niedrigem²²⁶Ra- und²²²Rn-Gehalt zu analysieren.

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Measurement of small amounts of radium and radon

Summary Various procedures employed for the measurement of slight²²⁶radium and²²²radon contents have also been used for the radiation hygiene. A cylindrical scintillation chamber of the most favorable dimensions offers the possibility of checking persons who have incorporated²²⁶Ra, without prior concentration of the breath-radon, and also in the analysis of foods and other samples that contain minute amounts of²²⁶Ra and²²²Ra.

     

Radionuclide levels and temporal variation in phosphogypsum

Summary Three samples of phosphogypsum of different ages were analyzed for natural radioelements using high-resolution gamma-ray spectrometry. The phosphogypsum samples were taken from the filter of a 10-year old pile, and a 50 year old pile. The distribution of ²²⁶Ra remains relatively constant as a function of storage time (up to 50 years) which confirms the immobility of ²²⁶Ra in the phosphogypsum matrix. However, the concentration of ²³⁸U and ²³² Th have shown a decreasing tendency going from the most recent sample to the oldest. For radionuclides belonging to the ²³² Th series, we noticed an enrichment factor of 1.5 for ²²⁸Ac in the most recent phosphogypsum, whereas the right proportions exist for the other two samples. This is due to the fact that most of the thorium fractionates to the phosphoric acid during the production process and the equilibrium between ²³² Th and its descendants is not yet reached for fresh phosphogypsum.     

Measuring <Superscript>137</Superscript>Cs, <Superscript>40</Superscript>K and decay products of <Superscript>226</Superscript>Ra and <Superscript>232</Superscript>Th in samples of different nature by a multidetector spectrometer

A coincidence method for measuring ¹³⁷Cs, ⁴⁰K, ²²⁶Ra and ²³²Th decay products activity in soil, vegetation and fish samples, was applied to the six-crystal gamma-coincidence spectrometer PRIPYAT-2M. In this way, some problems appeared in simultaneous measurement of ¹³⁷Cs, ²²⁶Ra and ²³²Th by NaI(Tl) detectors and the PRIPYAT-2M spectrometer were solved. The obtained results were agreeable with the HPGe spectrometer ones.