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Liquid Scintillation Counting (LSC) gross alpha/beta screening is a valuable tool for providing rapid laboratory response for the analysis of human clinical urine samples during a large-scale radiation incident event. Verification of method performance, as required for clinical laboratory testing, is accomplished by the evaluation of routine, periodic measurements of radioactive spiked samples for quality control, performance testing, and accuracy checks. Radionuclide stability of alpha and beta emitters in urine for LSC analysis is an important consideration. The purpose of this work is to demonstrate optimal preparations and storage conditions of samples used for method verification. [ABSTRACT FROM AUTHOR]

The adsorption of actinide ions (Am(III) and U(VI)) from aqueous solutions using pristine and oxidized carbon fabrics was investigated by means of batch experiments at different pH values (pH 4, 7 and 9) and temperatures (25, 35 and 45 °C) under ambient atmospheric conditions. The experimental results indicated that both the pH and the fabric texture affected the adsorption rate and the relative removal efficiency, which was 70% and 100% for Am(III) and U(VI), respectively. The Kd (L/kg) values for U(VI) were generally found to be higher (2 < log10(Kd)< 3) than the corresponding values for Am(III) adsorption (1.5 < log10(Kd) < 2). The data obtained from the experiments regarding the temperature effect implied that the relative adsorption for both actinides increases with temperature and that adsorption is an endothermic and entropy-driven reaction. The application of the fabrics to remove the two actinides from contaminated seawater samples showed that both the relative removal efficiency and the Kd values decreased significantly due to the presence of competitive cations (e.g., Ca2+ and Fe3+) and complexing anions (CO32−) in the respective waters. Nevertheless, the removal efficiency was still remarkable (50% and 90% for Am(III) and U(VI), respectively), demonstrating that these materials could be attractive candidates for the treatment of radionuclide/actinide-contaminated waters. [ABSTRACT FROM AUTHOR]

We report a new measurement of the 60 keV transition from 241Am. It uses a metallic magnetic calorimeter gamma-ray detector calibrated in the region around 60 keV by four accurately known X-rays and gamma rays from the decay of 169Yb. We determine an energy of 59,539.3 ± 0.3 (stat) ± 0.3 (syst) eV, which is 1.6 ± 0.4 eV lower than the current literature value of 59,540.9 ± 0.1 eV. We discuss the sources of this uncertainty and approaches to address them.

Silicone rubbers are a good choice for shielding materials because of having elastic and attenuating properties as well as cost-effectiveness. Thus, the aim of this study was to prepare ground-breaking silicone rubber samples by adding WO3-nanoparticles and testing the performance of their radiation shielding ability against Cs-137, Co-60, and Am-241 gamma energy. Increasing the concentration of WO3 nanoparticles in silicone rubber (SR) led to decreasing the half-value layer (HVL) and mean free path (MFP) values determined for the samples tested. Furthermore, the values of MFP and HVL upsurged according to the enhancement of the photon energy. It is noteworthy that the prepared silicone rubber (SR) systems with 50 and 60 wt% concentrations of WO3-nanoparticles displayed lower HVL than the Bi2O3-containing silicone rubber (SR) systems. In the same way, studied silicone rubber SR-W60 represented the lowest HVL comprising iron ore containing silicone rubber. [ABSTRACT FROM AUTHOR]

The industrial production of 3D printing is known as additive manufacturing (AM), in which a computer controls the process of producing 3D objects. Although x-ray computed radiography (XCT) is extensively used in the quality control and testing of additive manufacturing products, the gamma-ray radiography capabilities for these applications still need to be investigated. This study aimed to evaluate the performance of gamma-ray radiography using americium-241 (Am-241) as the gamma source. Here, we inspected fused deposition three-dimensional (3D) modeling products produced from polylactic acid (PLA) as thermoplastic samples. Radiographic testing of 3D-printed thermoplastic samples was performed using Monte Carlo simulations and validated by experimental studies. We used Am-241 (gamma-ray source) to conduct simulations and experiments investigations; two simulations were used: one by using 59.6 keV energy of gamma-ray and the other using all gamma-ray energies, including 16.96 keV, 26.3446 keV% 2.31 up to 662.40 keV. Also, we performed the x-ray radiography test to be used as a standard. The results showed that the defect detectability in the 3D-printed PLA samples using Am-241 as a gamma-ray source is comparable to that of x-ray results. This study concluded that the Am-241 could be used as the gamma-ray source to perform the radiography test for the products produced by 3D-printed thermoplastics.

This work is focused on the phytoremediation of radionuclides using eukaryotic green microalgae Chlamydomonas reinhardtii, Scenedesmus obliquus, and Chlorella vulgaris. This study highlights the potential use of microalgae in the process of phytoremediation in polluted aquatic solutions due to the unique cellular mechanism of uptake of different radionuclides. The kinetics of radionuclide removal from the samples was described according to the first-order kinetics and expressed by the rate constant k and calculated for each microalga at the most suitable pH. The activity of 137Cs and 60Co was measured in the presence of S. obliquus or C. reinhardtii and the activity of 241Am and 239Pu was measured in the presence of C. vulgaris. A significant decrease of activity of 137Cs was observed using C. reinhardtii with a rate constant of 2.4 Bq min−1 and S. obliquus after 3 h of incubation at pH 7 with rate constant of 2.5 Bq min−1. Chlorella vulgaris was able after 3 h of incubation to remove 241Am and 239Pu up to 90 and 70% in aquatic solutions at pH 1.7 and pH 1.5, with rate constants of 4.4 mBq min−1 and 2.8 × 10−2 mBq min−1, respectively. Ecologically suitable methods for the decontamination of liquid radioactive waste or radioactively contaminated areas are becoming more and more important due to the pollution of the planet. We believe that phytoremediation of radionuclides using microalgae is one of the optimal ecological methods to decontamination of radioactive waste. Microalgae as unicellular organisms have a number of advantages over the other organisms used in bioremediation—high level of tolerance to the environment, fast growth rates, high tolerance to various pH levels, etc. In this study, we used 3 different strains of microalgae for phytoremediation of various radionuclides (137Cs, 60Co, 241Am, and 239Pu). This research was focused on ex situ phytoremediation of radionuclides using microalgae at various pH levels of radioactively contaminated solutions. Due to the ability of microalgae to adapt to sometimes even extreme pH values, this research may be interesting for many institutions and researchers dealing with more environmentally friendly methods of decontamination of radioactive waste. [ABSTRACT FROM AUTHOR]

Abstract Nuclear batteries in the form of a semiconductor and radioisotope combination, whether of a betavoltaic or alphavoltaic, are promising miniature power sources due mainly to their potential to attain high power densities with long shelf and operational lifetime. Limitations in the performance of this type of nuclear battery consist typically of low power conversion efficiencies (PCE @ 0.1-3.6%), small output power (< 25 mW/cm3, mostly at nW), and radiation damage to the hosting semiconductor devices. In this paper, we have proposed and experimentally validated different techniques to improve nuclear batteries' PCE. A thin scintillator layer has been added into the battery structure to boost PCE through the combination of indirect (light generation) and direct (electron–hole pair generation) collection of radiation energy. The scintillator layer also serves as an energy degrader to reduce the charged particles' energy, consequently increasing their stopping power and energy deposition in the sensitive region of the devices. Highlights • A thin scintillator layer can boost PCE of an alpha-voltaic battery. • PCE is increased by combining direct and in-direct collection of radiation energy. • The scintillator increases energy deposition by reducing alpha particle's energy. • 4h-SiC voltaic battery was tested with PVT coated 241Am source. [ABSTRACT FROM AUTHOR]

Accurate detection of low-level radioactivity is critical in decommissioning. However, commercial sources used for calibration lack representativeness due to their flat surface. The objective of this work is to produce flexible and large area surface sources for alpha and beta emitters by functionalising aluminium foil. Functionalisation strategies were developed to provide these sources. The manganese oxide coated sample shows the highest fixation yield for 241Am: (70.0 ± 2.6)% and conforms to ISO 8769 for uniformity (92%). • Binding radionuclides chemically to a surface limits radiation self-absorption. • Flexible surface sources of Eu-152 and Am-241 were produced using aluminium foils. • Their surface activity is traceable, from 2 to 25 Bq. cm−2, and can be adjusted. • Their uniformity can reach 92% and conforms to ISO 8769. [ABSTRACT FROM AUTHOR]

A manual microliter gravimetric dispensing technique is demonstrated using a micropipettor modified for use with removeable microcapillaries. Liquid scintillation sources were prepared from a well-characterized 241Am reference solution, providing a radiometric check of dispensed masses. Further experiments confirmed controlled dispensing of drops onto gold foils with losses ≤0.34(4) % of the total drop activity. A detailed measurement equation for the weighing technique, including the corrections for evaporation, is presented with a full accounting of associated uncertainties. • A method for manual deposition of microliter drops is described. • Masses are confirmed radiometrically with liquid scintillation counting of 241Am. • The full measurement model accounts for evaporation during weighing. • Drops are deposited onto gold foils with losses ≤0.34(4) %. [ABSTRACT FROM AUTHOR]

To address the shortage of availability of Pu-238 for space missions, while new initiatives for Pu-238 production are being undertaken, there is a need for exploration of the use of Am-241 as a possible replacement for Pu-238 since the stockpile of Am-241 from the nuclear weapons program has remained relatively intact. Previously, there have been studies of the risks and consequences of Pu-238 release in postulated accidents including, for example, the Final Safety Analysis Report (FSAR) for the Galileo Mission. Since this report used an ICRP-30 based model, and a later ICRP-66 model has become available, it is of interest to re-evaluate the previous results for Pu-238 and obtain new results for Am-241. We are reporting here the following results of calculations for inhalation doses using our own computational programs (as based on different models). The results include committed equivalent doses for Pu-238 particles using the Galileo FSAR model, the original ICRP-30 model, and the ICRP-66 model. We also calculated committed equivalent dose for Am-241 using the ICRP-66 model. The ICRP-30 and ICRP-66 results were obtained using assumptions of committed time and resuspension taken from the FSAR. We have found that the ICRP-66 predicts lower doses for Pu-238 than those predicted by the Galileo FSAR or ICRP-30. Also we have found that the Am-241 lung doses are lower than those of Pu-238 because of greater clearance of Am-241 from the lungs as compared with Pu-238. [ABSTRACT FROM AUTHOR]

241 Am has been deposited using a novel technique that employs a commercial inductively coupled plasma mass spectrometer. This work presents results of high-resolution alpha spectrometry on the 241 Am samples using a small area passivated implanted planar silicon detector. We have also investigated the mass-based separation capability by developing a 238 Pu sample, present as a minor constituent in a 244 Pu standard, and performed subsequent radiometric counting. With this new sample development method, the 241 Am samples achieved the intrinsic energy resolution of the detector used for these measurements. There was no detectable trace of any other isotopes contained in the 238 Pu implant demonstrating the mass-based separation (or enhancement) attainable with this technique. [ABSTRACT FROM AUTHOR]

Aeolian and pluvial processes represent important mechanisms for the movement of actinides and fission products at the Earth's surface. Soil samples taken in the early 1970's near a Department of Energy radioactive waste disposal site (the Subsurface Disposal Area, SDA, located in southeastern Idaho) provide a case study for studying the mechanisms and characteristics of environmental actinide and 137 Cs transport in an arid environment. Multi-component mixing models suggest actinide contamination within 2.5 km of the SDA can be described by mixing between 2 distinct SDA end members and regional nuclear weapons fallout. The absence of chemical fractionation between 241 Am and 239+240 Pu with depth for samples beyond the northeastern corner and lack of 241 Am in-growth over time (due to 241 Pu decay) suggest mechanical transport and mixing of discrete contaminated particles under arid conditions. Occasional samples northeast of the SDA (the direction of the prevailing winds) contain anomalously high concentrations of Pu with 240 Pu/ 239 Pu isotopic ratios statistically identical to those in the northeastern corner. Taken together, these data suggest flooding resulted in mechanical transport of contaminated particles into the area between the SDA and a flood containment dike in the northeastern corner, following which subsequent contamination spreading in the northeastern direction resulted from wind transport of discrete particles. [ABSTRACT FROM AUTHOR]

Effects of Americium-241 (Am), alpha-emitting radionuclide of high specific radioactivity, and tritium (H), beta-emitting radionuclide, on luminous bacteria Photobacterium phosphoreum were compared. Bioluminescence intensity served as a marker of bacterial physiological activity. Three successive stages in the bioluminescence response to Am and H were found under conditions of lowdose irradiation: (1) absence of effects, (2) activation, and (3) inhibition. They were interpreted in terms of bacterial response to stressfactor as stress recognition, adaptive response/syndrome, and suppression of physiological function ( i.e. radiation toxicity). Times of bioluminescence activation (TBA) and inhibition (TBI) were suggested as parameters to characterize hormesis and toxic stages in a course of chronic low-dose irradiation of the microorganisms. Values of TBA and TBI of Am were shorter than those of H, revealing higher impact of alpha-irradiation (as compared to beta-irradiation) under comparable radiation doses. Increases of peroxide concentration and NADH oxidation rates in Am aquatic solutions were demonstrated; these were not found in tritiated water. The results reveal a biological role of reactive oxygen species generated in water solutions as secondary products of the radioactive decay. The study provides a scientific basis for elaboration of bioluminescence-based assay to monitor radiotoxicity of alpha- and beta-emitting radionuclides in aquatic solutions. [ABSTRACT FROM AUTHOR]

Abstract: This research explores the feasibility of using gamma-ray radiography in medical imaging. We will show that gamma-ray medical radiography has the potential to provide alternative diagnostic medical information to X-ray radiography. Approximately one Ci Am-241 radioactive source which emits mono-energetic 59.5keV gamma rays was used. Several factors that influence the feasibility of this study were tested. They were the radiation source uniformity, image uniformity, and image quality parameters such as contrast, noise, and spatial resolution. In addition, several gamma-ray and X-ray images were acquired using humanoid phantoms. These images were recorded on computed radiography image receptors and displayed on a standard monitor. Visual assessments of these images were then conducted. The Am-241 radioactive source provided relatively uniform radiation exposure and images. Image noise and image contrast were mainly dependent on the exposure time and source size, whereas spatial resolution was dependent on source size and magnification factor. The gamma-ray humanoid phantom images were of lower quality than the X-ray images mainly due to the low radioactivity used and not enough exposure time. Nevertheless, the gamma-ray images displayed most of the main structures contained in the humanoid phantoms. Higher exposure rates and thus lower exposure times were estimated for different pure Am-241 source sizes that are hypothesized to provide high quality images similar to X-ray images. For instance, a 10mm source size of pure Am-241 with 7s exposure time should produce images similar in contrast and noise to X-ray images. This research paves the way for the production and usage of a highly radioactive Am-241 source with the potential to lead to the feasibility of acceptable quality medical gamma-ray radiography. [Copyright &y& Elsevier]

Abstract: In a nuclear accident eventuality, the decontamination of potable water without disturbing the water quality is one of the major challenges. During this work, efforts have been made to reduce the contamination of americium (Am)-241 from potable water effectively by using calcium alginate followed by treatment with activated charcoal. Laboratory simulated experiments were carried out for the removal of low level of Am-241 from the potable water originated from groundwater, rain water and lake water. Water samples after filtering through 0.45μm filter paper were spiked in the range of 10–200Bq L−1 of Am-241 as Am(NO3)3. In the pH range 1–8, 60–98% Am was sorbed in the beads with a maximum observed at pH 4±0.2. It was observed that the variation of carbonate, bicarbonate, does not influence the sorption capacity of calcium alginate whereas the DOC decreased the sorption capacity in the range of 40–93% depending on DOC concentration. Ninety-eight to ninety-nine percent of Am is recovered from sodium alginate beads by using 0.6M HNO3. The mechanism of interaction of Am with calcium alginate is proposed based on attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR). [Copyright &y& Elsevier]

Abstract: Americium is a key element to design the FBR based nuclear fuel cycle, because of its long-term high radiological toxicity as well as a resource of even-mass-number plutonium by its transmutation in reactors, which contributes the enhancement of proliferation resistance. The present paper summarizes analysis of the individual Am and U samples irradiation in Joyo to re-evaluate the results of Pu isotopes in the measure of proliferation resistance, and to combine the results for the prediction of DU-Am irradiation especially in the production of Pu isotopes. By the prediction of DU-Am oxide fuel in fast reactor environment with detail fuel irradiation analysis, it was confirmed that neutron moderation and fuel size affects the produced Pu isotope and its vector due to the very high sensitivity of 238U resonance capture reaction, the larger diameter fuel is more preferable in the case of moderated neutron spectrum environment for denaturing Pu in fast reactor blanket. Finally proliferation resistance of all the Pu produced in U, Am sample irradiation and DU-Am fuel irradiation prediction were evaluated based on decay heat and spontaneous fission neutron rate, and it was confirmed 241Am produces un-attractive Pu to abuse from the beginning to the end of irradiation, and more than 2% of 241Am doping is required to enhance the proliferation resistance of Pu to MOX grade and Kessler’s proposal in moderated neutron spectrum environment in fast reactor. [Copyright &y& Elsevier]

Abstract: The effect of americium-241 (241Am), an alpha-emitting radionuclide of high specific activity, on luminous bacteria Photobacterium phosphoreum was studied. Traces of 241Am in nutrient media (0.16–6.67 kBq/L) suppressed the growth of bacteria, but enhanced luminescence intensity and quantum yield at room temperature. Lower temperature (4 °C) increased the time of bacterial luminescence and revealed a stage of bioluminescence inhibition after 150 h of bioluminescence registration start. The role of conditions of exposure the bacterial cells to the 241Am is discussed. The effect of 241Am on luminous bacteria was attributed to peroxide compounds generated in water solutions as secondary products of radioactive decay. Increase of peroxide concentration in 241Am solutions was demonstrated; and the similarity of 241Am and hydrogen peroxide effects on bacterial luminescence was revealed. The study provides a scientific basis for elaboration of bioluminescence-based assay to monitor radiotoxicity of alpha-emitting radionuclides in aquatic solutions. [Copyright &y& Elsevier]

A coniferous woodland in the vicinity of the British Nuclear Fuels reprocessing plant at Sellafield, Cumbria, was used to examine the spatial, temporal and depth distribution of 134Cs, 137Cs, 238Pu, 239+240Pu and 241Am in soil and leaf litter. All the radionuclides, with the exception of 134Cs, showed a consistent fall in accumulated soil and litter deposits with increasing distance from the woodland edge nearest to Sellafield. 137Cs levels in soil declined from 53 to 28 kBq m-2, 239+240Pu from 5.5 to 3.6 kBq m-2 and 241Am from 2.9 to 1.1 kBq m-2 within 100 m of the forest edge. This decline is attributed to greater deposition occurring at the leading edge of the woodland. The uniform deposition pattern of 134Cs in soil is consistent with the hypothesis that, at the time of sampling, these deposits derived largely from wet deposition during passage of the Chernobyl plume over Cumbria in May 1986. Results for the leaf litter indicate a similar spatial distribution to that observed in soil. Radionuclide concentrations were also similar but this is not attributable to adventitious soil contamination because significant differences between isotopic ratios of 134Cs:137Cs and 238Pu: 239+240Pu imply that the contamination on leaf litter is of more recent origin than that in soils. [ABSTRACT FROM AUTHOR]