Search

Copyright of Atomic Energy Science & Technology is the property of Editorial Board of Atomic Energy Science & Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In this study, a method for selective separation of 63Ni and 55Fe with simultaneous wash-out of 60Co was developed. Purification of 63Ni and 55Fe was carried out using a chelating ion-exchange resin Chelex 100. The elaborated procedure was applied for aqueous and stainless steel matrices. Average recoveries were around 80% for both isotopes, confirmed by ICP-MS and LSC measurements. 60Co, interfering with the isotopes spectra in the same energy range, was washed-out from the system prior to 63Ni and 55Fe separation. The most important advantages over existing methods are short separation time (c.a. 8 h), application of a single chromatographic column and overall simplicity. [ABSTRACT FROM AUTHOR]

To monitor radioactivity and its emissions in retired nuclear facilities, this study established an analytical method for 63 Ni and 55 Fe in mixed soil samples from a decommissioning reactor. After ashing at 400 °C for 4 hours, the sample was dissolved in a mixture of concentrated hydrochloric acid, nitric acid, and hydrofluoric acid, and then heated to dryness and dissolved in 9 mol/L hydrochloric acid. Subsequently, 63Ni and 63Fe were separated and purified using sodium hydroxide precipitation, anon exchange chromatography, and nickel specific rein extraction, and then measured by the liquid scintillation method. The results showed that the final stable recovery rates of Ni and Fe were 98.8% and 95.8%, respectively. The minimum detection limit and minimum detectable activity for 63Ni and 55Fe were 208 (counting) and 0.041 Bq,208 (counting) and 0.144 Bq, respectively. The actual activity concentrations of 63Ni and 55Fe in the samples were 76.9 Bq/g and 30.4 Bq/g, respectively. The recovery simulation experiment was conducted using standard soil substances, achieving a recovery of over 95%. Experiments were conducted on the separation of Ni and Fe from various elements using alkali precipitation and anon exchange chromatography, respectively. Among them, the sodium hydroxide precipitation method effectively coprecipitated Ni and Fe, and removed most of Re,Sr, and all Cs at pH value between 8.7 and 11.1. The decontamination factors for Co,Fe, and Zn in the nickel fraction of anion exchange chromatography were all above 660, wide the decontamination factors for Co,Eu,Mn,Ni, Sr,Zn, and Zr in the iron fraction were all above 2 000. This work also investigated the purification effects of DMG precipitation method and nickel specific resin method on Ni, respectively. The recovery of Ni by DMG precipitation method was 87.14%, and the recovery of Ni by nickel resin method was close to 100% when the nickel interference element ratio was above 10:1. Moreover, the purification effect of interference elements such as Ba, Eu, Fe, Mn, and Sr was the best. Therefore, before using nickel resin, other methods such as alkali precipitation and ion exchange resin should be used for preliminary separation. This method is simple to operate and has a high recovery, which can meet the needs of monitoring 63Ni and 55Fe in retired nuclear facilities. [ABSTRACT FROM AUTHOR]

In order to optimize the measurement conditions of 55Fe by liquid scintillation counting, the effect of three kinds of commercial scintillation cocktail and two efficiency correction methods on LSC measurements of 55Fe was tested. Configuration of 55Fe samples with the same matrix as after radiochemical treatment for measurement, Ultima Gold AB has the highest sample loading among the three kinds of scintillation cocktail; the counting efficiency of Ultima Gold LLT is the highest and the MDA is the lowest under different miscibility ratios, and the maximum detection efficiency of Ultima Gold LLT is 49.1% when the miscibility ratio is 1∶4, while the MDA is 0.12 Bq. If the sample uses scintillation cocktail different from the quenched standard source, it will have an impact on the accuracy of the results, with an absolute value of maximum average relative deviation is 3.55% between the measured and expected values under experimental conditions. Comparing the two quenching calibration methods of tSIE and TDCR, the TDCR method can eliminate the influence caused by the simultaneous presence of color and chemical quenching on the 55Fe LSC measurement results, and is a more accurate method for measuring 55Fe. The relative deviations between the measured and expected values obtained from the color and chemical quenching calibration curves are -0.35% to 0.40% and -0.91% to -0.16%, respectively, as verified by the spiked samples.

Radioactive wastes, such as concrete and soil, generated during the decommissioning of nuclear facilities contain radionuclides with varying levels of activity. Beta-emitting radionuclides can be identified after thoroughly decomposition and separation from the sample matrix. Among these radionuclides, Fe–55 and Ni–63 play vital roles in the management of radioactive waste from nuclear facilities owing to their pronounced incidence and high mobility in the environment. This study documents the results of the extraction efficiencies of Fe and Ni with a rapid pretreatment method within 2 h by wet digestion methods using hydrochloric acid and nitric acid (3:1, v/v). The average Fe and Ni extraction efficiencies for certified reference materials in soil and sediment matrix were evaluated to be 84–94% and 90–96% with analytical precision within 5%, respectively. [ABSTRACT FROM AUTHOR]

The measurement of 55Fe and 63Ni is of great significance for the monitoring of liquid effluents from nuclear power plant. In this paper, a combined analysis method of 55Fe and 63Ni in liquid effluent sample is established. 55Fe and 63Ni are enriched by precipitation of iron hydroxide and nickel hydroxide and separated by TRU resin and nickel resin, then measured by low-level liquid scintillation spectrometer. Also the relevant measurement conditions are analyzed and studied. When the amount of sample is 1.0 L and the measurement time is 60 min, the detection lower limit of this method is 0.06 Bq/L for 55Fe and 0.02 Bq/L for 63Ni, which meets the analysis requirements of 55Fe and 63Ni in liquid effluents of nuclear power plant.

A pilot study to quantify 55Fe in steel from a reactor vessel of a nuclear power plant by accelerator mass spectrometry (AMS) without any chemical sample preparation was validated by liquid scintillation counting (LSC) and AMS after radiochemical separation. AMS reaches an uncertainty < 10% at the 1 kBq gFe−1 level within less than 10 min measuring time. The background was < 3 Bq gFe−1, presently limited by the short measurement time. The new instrumental AMS method for analysing 55Fe from neutron capture production is reasonable and fast compared to other analytical methods. [ABSTRACT FROM AUTHOR]

Background55Fe is a low-energy radionuclide that is difficult to measure and decays to a ground state of 55Mn through pure electron capture (EC), accompanied by the emission of Auger electrons and low-energy X-ray. As iron is the main component of nuclear reactor building materials, significant amounts of 55Fe have been produced in nuclear reactors and other neutron-producing nuclear facilities.PurposeThis study aims to develop an 55Fe nuclide standard through the absolute measurement of 55Fe activity and provides activity traceability services for 55Fe measuring instruments to ensure the accuracy and consistency of the measurement results of calibration instruments.MethodsThe liquid scintillation triple-to-double coincidence ratio (TDCR) method was applied to determining the activity of 55Fe. First, based on nuclear and atomic data of 55Fe, the electron deposition spectrum of 55Fe in a scintillator was calculated using a random atomic rearrangement model. Second, the counting efficiency of single-energy electron was computed based on the free parameter model. The total efficiency curve of 55Fe was then obtained by summing the efficiency of all deposited electrons. Finally, the experimental counting efficiency was derived by measuring the TDCR value and combining it with the total efficiency curve to realize an absolute measurement of 55Fe activity.ResultsThe experimental results show that correction factors for the asymmetric effect of photomultiplier tube (PMT) quantum efficiency obtained on test samples are between 1.001 and 1.005. The measured specific activity of 55Fe is 94.15 kBq∙g-1 with a relative standard uncertainty of 0.45%. Experimental efficiency is better than 63% for double coincidence logic sum of liquid scintillation counter.ConclusionsThis study demonstrates that low relative standard uncertainty of 55Fe activity could be achieved using the liquid scintillation TDCR method with high detection efficiency, and more consistent measurement results can be obtained after applying the asymmetry correction of PMT quantum efficiency.

A radiochemical method was developed for the accurate 55Fe determination in various radioactive waste, in particular samples contaminated with 241Pu. It consisted of three purification steps based on first ammonium hydroxide precipitation, and then anion exchange separation followed by TRU®-based extraction chromatography. It was characterized by an iron recovery yield of about 80% for all the studied samples and a 60Co decontamination factor of 106. In comparison to a standard protocol based on iron cupferrate extraction in chloroform, an improvement of a 30-fold factor was achieved towards plutonium. The developed TRU®-based procedure was validated by participating in interlaboratory exercises. [ABSTRACT FROM AUTHOR]

We present the validation of a radiochemical procedure for the determination of 55Fe and 63Ni in water and steel samples from nuclear decommissioning activities. The in-house validation was an essential requirement of the accreditation to ISO/IEC 17025. A combination of co-precipitation, anion chromatography and extraction chromatography steps was used for separating and purifying both radionuclides. The activities were measured by liquid scintillation counting. Due to the lack of reference materials, the method was validated by analysing simulated samples and by the standard addition technique. The parameters precision/accuracy, repeatability/linearity, selectivity/specificity, decision threshold, detection limit and uncertainty of the method were evaluated. [ABSTRACT FROM AUTHOR]

A method for sequential determination of 55Fe and 63Ni in leaching solution of cement solidification using liquid scintillation counting (LSC) was developed. In this method, 55Fe and 63Ni were first precipitated in the form of hydroxide and subsequently purified by anion exchange chromatography and dimethylglyoxime precipitation. After the purification, 55Fe and 63Ni were determined by LSC. The performance of the method was examined, and minimum detectable activity concentration was determined to be 0.82 Bq L−1 for 55Fe and 0.42 Bq L−1 for 63Ni in leaching solution samples with a counting time of 1 h. High decontamination factors for 55Fe and 63Ni were also obtained. [ABSTRACT FROM AUTHOR]

Abstract: The obtained results showed that the Sr resin can be used for the chromatographic separation of Fe (III) and Sr (II) ions by using a mixture of HCl and HNO3. It was shown that the binding strength of Fe (III) decreases with increasing concentration of HNO3 while the binding strength of Sr (II) increases. It was found that the optimal bonding strength is achieved in 6mol/L HCl:3mol/L HNO3 and varying concentrations of acid in the mixture allow their selective separation. On basis of these results, a method for the separation of 55Fe and 89,90Sr from liquid samples which consists of binding of Fe and Sr on Sr resin and separation from a number of elements by 6mol/L HCl:3mol/L HNO3 and their mutual separation by eluting of Sr with 4mol/L HCl is established. The method enables efficient simultaneous separation (with high recovery) of 89,90Sr and 55Fe and in combination with Čerenkov counting rapid determination of 89,90Sr. [Copyright &y& Elsevier]

Nuclear techniques and other techniques using ionising radiation represent a valuable tool in non-destructive diagnostics applied to archaeological finds and objects of arts, namely for determining the composition of materials used in the production of artefacts. X-ray fluorescence analysis, both in its energy form and in its wave dispersive form, is one of the most widespread methods using ionising radiation to study the elemental composition of materials. It is frequently used for studies of various cultural and historic relicts and objects of art. This work summarizes the authors’ experience with X-ray fluorescence analysis in investigating historical frescos namely by means of portable provide spectroscopic devices. The results of these measurements information on the composition of the pigments, enable the comparison of processes used in the fabrication of pigments by individual artists, and in many cases offer information on how to repair the damaged parts.

Abstract: The implementation of 63Ni and 55Fe determination methods in an environmental laboratory implies their validation. In this process, the uncertainties related to these methods should be analysed. In this work, the expression of the uncertainty of the results obtained using separation methods followed by liquid scintillation counting is presented. This analysis includes the consideration of uncertainties coming from the different alternatives which these methods use as well as those which are specific to the individual laboratory and the competency of its operators in applying the standard ORISE (Oak Ridge Institute for Science and Education) methods. [Copyright &y& Elsevier]

Ionic nutrition is essential for plant development. Many techniques have been developed to image and (or) measure ionic movement in plants. Nevertheless, most of them are destructive and limit the analysis. Here, we present the development of radioisotope imaging techniques that overcome such restrictions and allow for real-time imaging of ionic movement. The first system, called macroimaging, was developed to visualize and measure ion uptake and translocation between organs at a whole-plant scale. Such a device is fully compatible with illumination of the sample. We also modified fluorescent microscopes to set up various solutions for ion uptake analysis at the microscopic level. Both systems allow numerical analysis of images and possess a wide dynamic range of detection because they are based on radioactivity. [ABSTRACT FROM AUTHOR]

Abstract: This work describes the procedure followed by the Laboratório de Metrologia Nuclear (LMN) for the standardization of 55Fe by the tracing method. This technique was applied using two radionuclides, which decay by the electron capture process followed by a prompt gamma-ray, namely 51Cr and 54Mn, as tracers. The calibration was performed in a 4πβ–γ coincidence system. The efficiency was obtained by selecting a gamma-ray window set at the 320keV total absorption peak for 51Cr and at 834keV for 54Mn. [Copyright &y& Elsevier]

Abstract: The results of an international comparison of activity measurements of a solution of 55Fe organized by the BIPM in 2005 are reported and analysed. This exercise, which follows the procedures of the CIPM mutual recognition arrangement to update older comparisons, is a renewal of the comparison organized by the BIPM that took place in 1978. A EUROMET comparison was organized in 1996 specifically to compare activity measurements of a 55Fe solution by means of liquid-scintillation techniques. Results of these three comparisons are presented and discussed in this paper. The radionuclide solution was provided by the NPL, which also distributed the samples to the participants. The activity of the ampoules was measured by 16 laboratories using 12 methods producing 25 results. Some general considerations on uncertainty assessments pertaining to the different techniques used are drawn. The outcome of four different estimators is compared from which the presence of at least one outlier can be confirmed. Further measurements should be made to try to reduce the discrepancy between the results. To date the outcome of the present comparison does not show an improvement to that of the 1996 comparison. [Copyright &y& Elsevier]

Abstract: NMIJ participated in the CCRI (II) key comparison of 55Fe activity measurement. A planar-type Si(Li) detector and a liquid-scintillation counter were used to calibrate the activity. The calibration result obtained by the Si(Li) detector agreed with that obtained by the liquid-scintillation counter using the CIEMAT/NIST method within uncertainty. The result was reported to the BIPM in 2006. The activity of 55Fe was also measured by using a 2π pressurized proportional counter. The result obtained by the 2π pressurized proportional counter agreed with the above results within uncertainty. The measurement by the Si(Li) detector was very simple and its procedure was a combination of conventional methods. The measurement by the liquid-scintillation counter is most popular to calibrate the activity of 55Fe. However the Si(Li) detector is also useful. [Copyright &y& Elsevier]

Abstract: A solution of 55Fe was measured by using liquid scintillation counting (LSC)-TDCR method. The measurement was performed within the frame of the CIPM CCRI(II)-K2.Fe-55 comparison during the year 2006. Two computation codes were used for the calculation of detection efficiency, the difference between the results being analyzed. The photomultipliers asymmetry and its influence on the results, as well as the long-term stability are also analyzed. The influence of the variation of kB value over the activity value is compared with the case of 3H standardization. [Copyright &y& Elsevier]

Abstract: This paper presents comparison of two methods for the determination of 55Fe activity of waste waters discharged from the Krsko nuclear power plant (KNPP). Research was conducted on 12 composite samples of waste water collected in the waste monitor tank (WMT) during each month as well as on Analytics, Inc. cross-check sample. Results showed that the complicated and time-consuming method proposed by the Environmental Measurements Laboratory (EML) could be successfully replaced with a simple and fast based on the extraction of 55Fe from waste water by non-specific chelating agent ammonium-pyrrolidinedithiocarbamate (APDC) at pH 4 after separation from cobalt, and activity measurement by X-ray fluorescence spectroscopy (XRS). Results obtained by the XRS method were approximately 8.6% lower than those obtained by liquid scintillation spectrometer (LSC). The mean deviation of the XRS results from the activity of cross-check sample was 2.47%, which ensures that this method is accurate enough for environmental monitoring. [Copyright &y& Elsevier]

Abstract: The potential for measuring the radionuclides 41Ca and 55Fe was investigated with the 3MV tandem accelerator at VERA. Interestingly, up to now, no applications have been published for 55Fe using the technique of AMS. This is in strong contrast to 41Ca, which is routinely measured by medium and large tandem accelerators in various applications. Using CaF2 samples the quantification of 41Ca down to levels of a few 10−13 for the isotope ratio 41Ca/Ca has become possible with the use of the ΔTOF technique. Both nuclides, 41Ca and 55Fe were found to be of interest in nuclear astrophysics. A first application of 41Ca detection at VERA is the measurement of the 40Ca(n,γ)41Ca cross section at stellar temperatures. Similarly, of astrophysical interest is the production of 55Fe via neutron capture on 54Fe. To this end, different Ca and Fe blank and standard samples were investigated with the goal to establish an AMS method for 41Ca and 55Fe measurements. Indeed, low background levels for both radionuclides, 41Ca and 55Fe, were observed in these studies. The full separation power of VERA results in a very low detection limit, while still providing a high overall transmission. [Copyright &y& Elsevier]

Abstract: In this paper, we apply the CIEMAT/NIST method to the three low-Z electron-capture nuclides 54Mn, 55Fe and 65Zn by using the KLM and KL1L2L3M atomic rearrangement models, respectively. The counting efficiencies are computed with the new code EMILIA, which comprises an improved model for the interaction of low-energy X-rays with the scintillation cocktail. The calculated counting efficiencies are compared with experimental results. [Copyright &y& Elsevier]

Abstract: The half-life of 55Fe was determined experimentally and compared with literature values. A solid 55Fe source was prepared by electrodeposition and repeatedly measured in an X-ray detector at a constant, low solid angle. In total, more than six hundred measurements were performed over a period of ten months, corresponding to one third of the half-life. The experimental method and the corresponding uncertainty budget are presented. The result of 1005.2±1.4 days is slightly higher than the current recommended values. [Copyright &y& Elsevier]

Abstract: An analytical method for the determination of 63Ni and 55Fe in nuclear waste samples such as graphite, heavy concrete, aluminium and lead was developed. Different decomposition methods (i.e. ashing, acid digestion and alkali fusion) were investigated for the decomposition of the samples and for the separation of Fe and Ni from the matrix. Hydroxide precipitation was used to separate 55Fe and 63Ni from the matrix elements and ion exchange chromatography was used to separate 55Fe and 63Ni from the interfering radionuclides as well as from each other. The separated 63Ni was further purified by extraction chromatography. The purified 63Ni and 55Fe was then measured by liquid scintillation counting. The chemical yields of the separation procedures for 55Fe and 63Ni are above 90% and the decontamination factors for all interfering radionuclides are more than 105. The detection limits of the analytical method for 55Fe and 63Ni are 0.018 and 0.014Bq, respectively. The methods developed were used in the analysis of 55Fe and 63Ni in heavy concrete, aluminium and lead from two concrete cores and graphite from thermal column in the Danish research reactor DR-2 and the results are presented in this paper. [Copyright &y& Elsevier]

Background: Muscle tissue from various sources is known to promote nonheme-iron absorption. However, systematic studies of the dose dependency of this effect of meat on iron absorption from an inhibitory meal with low amounts of meat are lacking. Objective: We investigated the dose-response effect of small amounts of meat on nonheme-iron absorption from a meal presumed to have low iron bioavailability. Design: Forty-five healthy women with a mean (± SD) age of 24 ± 3 y were randomly assigned to 1 of 3 groups, each of which was served (A) a basic meal (rice, tomato sauce, pea purée, and a wheat roll) and (B) the basic meal with either 25, 50, or 75 g pork (longissimus muscle). Meal A contained 2.3 mg nonheme iron, 7.4 mg vitamin C, and 220 mg (358 μmol) phytate. Each meal was served twice, and the order of the meals was ABBA or BAAB. The meals were extrinsically labeled with 55Fe or 59Fe. Iron absorption was determined from measurements of 59Fe whole-body retention and the activity of 55Fe and 59Fe in blood samples. Results: Twenty-five grams meat did not increase nonheme-iron absorption significantly (P = 0.13), whereas absorption increased 44% (P < 0.001) and 57% (P < 0.001), respectively, when 50 and 75 g meat were added to the basic meal. In absolute values, this corresponds to an absorption that was 2.6% and 3.4% higher, respectively, than that with the basic meal after adjustment of the data to a level of 40% absorption from a reference dose. Conclusion: Small amounts of meat (= 50 g) significantly increase nonheme-iron absorption from a phytate-rich meal low in vitamin C. [ABSTRACT FROM AUTHOR]

Skipper-CCD can achieve deep sub-electron readout noise making possible the absolute determination of the exact number of ionized electrons in a large range, from 0 to above 1900 electrons. In this work we present a novel technique that exploits this unique capability to allow self-calibration and the ultimate determination of silicon properties. We performed an absolute measurement of the variance and the mean number of the charge distribution produced by 55Fe X-rays, getting a Fano factor absolute measurement in Si at 123K and 5.9 keV. A value of 0.1190(25) was found and the electron–hole pair creation energy was determined to be 3.752(2) eV. This technology opens the opportunity for direct measurements of the Fano factor at low energies. [ABSTRACT FROM AUTHOR]

Several measurements with aliquots from a 55Fe solution were carried out using two custom-built TDCR counters. The time between the initial and the last measurements is 2304 d, i.e. a length of more than two half-lives. The data were analysed to determine the half-life of 55Fe, which was found to be (1006.2 ± 1.0) d. The determined half-life is longer than the current values from nuclear data evaluations, but it is in good agreement with recent results obtained by Pommé et al. (2019). • TDCR measurements of 55Fe were analysed. • The half-life of 55Fe was found to be (1006.2 ± 1.0) days. • This half-life is longer than currently accepted values. [ABSTRACT FROM AUTHOR]