Alpha Spectrometry Research Articles

Study of 222−220Rn Measurement Systems Based on Electrostatic Collection by Using Geant4+COMSOL Simulation

Using Monte Carlo (with Geant4) and COMSOL simulations, the authors have defined a useful tool to reproduce the alpha spectroscopy of 222Rn, 220Rn and their ionized daughters by measurement systems based on electrostatic collection on a silicon detector, inside a metallic chamber. Several applications have been performed: (i) simulating commercial devices worldwide used, and comparing them with experimental theoretical results; (ii) studying of realization of new measurement systems through investigation of the detection efficiency versus different chamber geometries. New considerations and steps forward have been drawn. The present work is a novelty in the literature concerning this research framework.

3D printed field-deployable microfluidic systems for the separation and assay of Pu in nuclear forensics.

A compact field-deployable microfluidic system has been developed to improve timelines for the rapid analysis of debris in post-detonation nuclear forensics. We used a high-resolution 3D printer to miniaturize typical laboratory-based procedures into a fieldable platform. Microfluidic half-modules were produced for the purification of Pu from excess U, along with a portable alpha chamber for the following isotopic analysis of the Pu stream. A porous PTFE membrane is soaked with a hydrophobic tributyl phosphate (TBP) solution and is placed between two half-modules; separation is performed as a liquid-liquid extraction in an extraction channel across this membrane, where the forward and back-extractions occur within one complete module. Following separation, a 100 μL sampling of the Pu-bearing stream is injected into a small-footprint 3D printed alpha chamber for isotopic assay via alpha spectrometry as part of an online process. In this first demonstration of microfluidic separation coupled with online alpha spectrometry, high extraction yields have been obtained for Pu (98.9 ± 4.0)% and U (97.5 ± 2.5)%. The process uses less than 800 μL of solution with separation chemistry complete within 45 minutes and subsequent alpha spectrometry initiating 25 minutes after separation.

Оценка содержания изотопов плутония в почве в районе размещения хранилища радиоактивных отходов в городе Обнинске

One of the sources of radionuclides released into the environment are radioactive waste storage. The plutonium isotopes concentration in the soils of the territory adjacent to the former radioactive waste storage facility in Obninsk was estimated. The cause of pollution was the depressurization of one of the storage tanks and the release of radionuclides due to its overflow with surface and ground waters in the period from 1998 to 1999. Samples were analyzed by alpha spectrometry with preliminary radiochemical isolation with complete decomposition of soil samples. The Pu-239+240 content range in the surface soil layer was 3.7-9.6 Bq/kg, with an average value of 6.7 Bq/kg, which is an order of magnitude higher than the level of its global fallout. In some samples, significant amounts of Pu-238 are observed, the relative content of which is 10-50% of Pu-239+240, that exceeds the its relative content due to the global fallout which is 2-5%. The depth distribution of plutonium isotopes has been studied. It has been established those significant concentrations of plutonium are observed to the depth of 95 cm for this territory. There is no definite dependence of the distribution of plutonium isotopes along the vertical soil profile. The random distribution of plutonium to the soil depth indicates that the source of Pu-239+240 are groundwater. Elevated concentrations of plutonium isotopes in the soil surface of the territory under consideration, its significant concentrations at soil depth indicates that the contamination is a consequence of the leakage of plutonium isotopes from the radioactive waste storage facility in Obninsk. The same concentrations can be expected in the lowland of the adjacent territory.

Ultrasensitive detection of 244Pu in environmental samples by accelerator mass spectrometry

Plutonium radiochemical separation using TEVA resin and chemical recoveries determined by alpha spectrometry. Zero background measurement of 244Pu by AMS from environmental sediments from Bikini Atoll island and the Pacific Ocean.

Soil radon exhalation rate measurement in Duhok city by two techniques

Radon exhalation rate is the rate of radioactive radon gas that escapes from the soil into the atmosphere. In this study exhalation rate of radon was measured for 33 samples of soil, in four districts of Duhok province, using two different techniques: one using radon concentration and other using radium content, by both alpha and gamma spectroscopy. For the radon measurement, alpha-sensitive RAD7 detector was used. While in the second method, radon exhalation rate was expressed as a function of radium concentration, measured by well type NaI (Tl) detector and other soil parameters. Analysis, shows that the average of radon exhalation rate, by the first technique, varies from 14.6 ? 3.2 to 55.7 ? 1.6 Bqm-2h-1, while by the second technique, it varies from 13.3 ? 2.4 to 50.6 ? 4.1 Bqm-2h-1. Overall, the measured values, for both methods at all the sample points, present a good correlation and less than global mean average recommendation.

Could soluble minerals be hazardous to human health? Evidence from fibrous epsomite

From a toxicological point of view, particulates and fibres with high solubility in water and/or in biological environments have not been considered in detail and the knowledge to date in this area is very scarce. In this study, the water-soluble natural epsomite fibres from Perticara Mine (Italy) were investigated using SEM-EDS, XRPD, ICP-AES and alpha spectrometry measurements which were combined and integrated to characterise the fibres’ morphology, crystal chemistry and mineralogy. The morphological and morphometric results showed that most of the fibres are of inhalable size (Dae 5.09 μm) and can be potentially adsorbed from all parts of the respiratory tract. Chemical analysis reveals significant amounts of toxic elements (As, Co, Fe, Mn, Ni, Sr, Ti, Zn) and surprisingly high contents of radioactive isotopes (210Po and 228Th) in epsomite crystals, making the inhalation of these fibres potentially hazardous to human health. Through this study, we want to focus on soluble minerals, such as epsomite, which can be present in both natural and anthropic environments and have never been considered from the point of view of their potential hazard.

The Characterisation of an Alpha Spectrometry System using a Certificated Standard Source

The calibration parameters of a high resolution two-chamber alpha spectrometer dedicated to detect alpha radiation in environmental samples were evaluated and confirmed using a certified standard source containing 237Np, 241Am and 244Cm nuclides. The resolution and efficiency characteristics for the two ion-implanted solid state detectors (ULTRA AS series) in this system were evaluated at all possible detector-source distances. The characteristics related to the performance of alpha detectors against the alpha radiation emitted from the standard source used in the measurements and the results obtained were compared in detail.

Membranes for the Capture and Screening of Waterborne Plutonium Based on a Novel Pu-Extractive Copolymer Additive.

This contribution describes the fabrication of plutonium-adsorptive membranes by non-solvent induced phase separation. The dope solution comprised poly(vinylidene fluoride) (PVDF) and a Pu-extractive copolymer additive of PVDF-g-poly(ethylene glycol methacrylate phosphate) (EGMP) in dimethylformamide (DMF). The effects of casting conditions on membrane permeability were determined for PVDF membranes prepared with 10 wt% PVDF-g-EGMP. Direct-flow filtration and alpha spectrometry showed that membranes containing the graft copolymer could recover Pu up to 59.9 ± 3.0% from deionized water and 19.3 ± 3.5% from synthetic seawater after filtering 10 mL of 0.5 Bq/mL 238Pu. SEM-EDS analysis indicated that the graft copolymer was distributed evenly throughout the entire depth of the copolymer membranes, likely attributing to the tailing observed in the alpha spectra for 238Pu. Despite the reduction in resolution, the membranes exhibited high Pu uptake at the conditions tested, and new membrane designs that promote copolymer surface migration are expected to improve alpha spectrometry peak energy resolutions. Findings from this study also can be used to guide the development of extractive membranes for chromatographic separation of actinides from contaminated groundwater sources.

A comparison of alpha-particle and gamma-ray spectrometry methods for determination of 235U, 238U and 226Ra activity concentration in samples of coal, slag and fly-ash

In order to compare alpha-particle and gamma-ray spectrometry, the activity concentrations of 235U, 238U and 226Ra in samples of coal, slag and fly-ash from the thermal power plant “Nikola Tesla A”, Serbia, were determined by these two methods. Methods were compared and discussed from the point of view of its precision, difficulty to apply and complexity. Gamma-ray spectrometry was performed with HPGe (High Purity Germanium) spectrometer, while alpha activity was measured by PIPS (Passivated Implanted Planar Silicon) detector. For the alpha-particle spectrometry, the chemical procedures applied were chromatographic resin extraction for uranium isotopes and micro-coprecipitation for 226Ra. Thin alpha sources were prepared by electrodeposition and filtration through polypropylene membrane filter for uranium determination, while filtration technique was performed for radium sources. For the evaluation of the statistical difference between individual measurement results obtained by application of two methods Z - test was used. In order to evaluate the difference between two methods used, paired samples t-test and F-test were applied. Results show that there is no statistical difference between two methods used and that gamma-ray spectrometry is a valid alternative to time consuming alpha spectrometry.

A fast strategy to sequentially separate and determine 90Sr, 210Pb and 210Po in water samples using Sr resin

This study presents a rapid and novel sequential separation strategy based on extraction chromatography for determining 90Sr, 210Pb and 210Po in drinking water samples. It involves the use of Sr resin for the separation and then liquid scintillation counting and alpha spectrometry for the determination. The experimental results obtained showed that the proper acidic solution to quantitatively retain the aforementioned radionuclides is 3 M HNO3. The optimum eluents were determined for obtaining quantitative recoveries (70–80%) of 90Sr, 210Pb and 210Po. The method was validated with intercomparison water samples and is satisfactory in terms of minimum detectable activities, which are 50% lower than that established in RD 314/2016.

Semi-insulating GaAs detectors degraded by 8 MeV electrons up to 1500 kGy

Radiation degradation of semi-insulating GaAs detectors by 8 MeV electrons up to doses of 1500 kGy is studied in this paper. The influence of irradiation on GaAs material parameters and on spectrometric and electrical properties of fabricated detectors is evaluated. The detector material was degraded before contact preparation, which ensured separation of radiation degradation solely to the bulk material, excluding the contact degradation. The positron annihilation lifetime spectroscopy (PALS) was involved to characterize the substrate material together with galvanometric measurements. Radiation-induced mono-vacancies were clearly identified by PALS in the irradiated materials with increasing concentration up to 2.8 × 1016 cm−3 at maximal applied dose. In correlation with defect concentration the electron Hall mobility decreased with dose down to 3270 cm2 V−1 s−1 and resistivity increased up to 5.22 × 108 Ω cm at 1500 kGy. The bulk material properties influenced the parameters of fabricated detectors. The detectors lost their current blocking behaviour at 1000 kGy according to current-voltage measurements. The charge collection efficiency during alpha-particle and gamma ray measurements almost exponentially decreased with applied dose from initial 40% down to 5% at 1500 kGy in the case of alpha spectrometry and from 48% to 12% at 500 kGy for gamma spectrometry.

Radon concentration measurement in water reservoirs for some areas of north Baghdad by RAD7

Radon is a naturally occurring, odorless, colorless, radioactive, tasteless, and noble gas. Radon concentrations have been measured by the usage of alpha spectroscopy (RAD-7). The RAD-7 measuring process is based on detecting alpha particles produced from the disintegration of radon and its products using a solid-state alpha detector (usually silicon), and then converting alpha radiation directly to an electrical signal. The radioactivity of radon gas was measured in forty-two samples from reservoir water for different areas north of Baghdad utilizing a RAD7 detector. This study proved that the high value of radon concentrations was less than the permissible limit as recorded by the World Health Organization.

Measurement of Natural Radionuclides in Drinking Water and Risk Assessment in a Volcanic Region of Italy, Campania

The physical–chemical properties of water are closely linked to the geological nature of the site where they are located. This aspect becomes even more interesting when analyzing the natural radionuclides in the drinking water of a volcanic territory such as Campania in southern Italy. This study concerned the measurement of activity concentration of gross alpha and beta, radon, and tritium to evaluate their biological impact. The measurements were carried out using alpha spectrometry for alpha emitters, proportional counter for beta emitters, the electret system for radon in water, and finally liquid scintillation for the measurement of tritium concentration. The biological impact was assessed considering the indicative dose, if applicable, and the effective annual dose of radon. Although the results show that the values are below international and national references, the radiological characterization of drinking water is of fundamental importance to optimize the radiation protection of the population.

Development of a rapid method for extraction of uranium from uranium bearing materials using ionic liquid as extracting agent from basic media

The paper presents the development of a rapid method for the direct determination of uranium using liquid scintillation analysis in uranium bearing materials with different uranium concentrations and with different impurity levels (U-ore, Uranium ore concentrate (UOC) and U-metal). Uranium extraction was carried out using hydrophobic ionic liquid Aliquat-336 thiosalicylate, ([A-336][TS]) from diluted samples in basic medium followed by liquid scintillation counting (LSC). Extraction efficiencies for uranium from aqueous medium was studied with very small volumes of ionic liquid under varying volume, pH and uranium concentration of the aqueous medium. Maximum extraction efficiency was achieved near pH 8–11. Uranium was successfully re-extracted from organic medium with nitric acid and electroplated onto stainless steel planchette for alpha spectrometry determination. Maximum re-extraction efficiency with 1 M HNO3 combined with electroplating efficiency observed was 80%. The methodology was applied for real samples. The uranium extraction efficiency using ionic liquid was about 85% for U-metal and UOC samples with comparatively low impurity level; whereas extraction efficiency for U-ore samples was found to be less than 40%. The technique can be applied for nuclear forensic applications as well as nuclear emergency scenarios for a quick initial assessment and isotopic analysis of uranium in the samples.

Assessment of intake of 210Po and 210Pb isotopes from cow’s milk in Poland

ABSTRACT Milk has been known for its nutritional properties for centuries and is often the staple of the diet in many countries. Therefore, monitoring of milk composition seems to be a relevant task as it was the purpose of this study to compare levels of 210Po and 210Pb in several Polish voivodeships. The methodology was based on mineralization, loss on an inorganic matrix and concentration measurement on an alpha spectrometer. The concentrations of 210Po and 210Pb in collected milk samples were measured using alpha spectrometry and calculations, respectively. The results showed that the lowest concentration of 210Po is 2.8 ± 0.2 mBq l−1 and the highest is 56.3 ± 0.7 mBq l−1 while the 210Pb concentrations are in the range from 2.8 ± 0.2 to 44.0 ± 1.7 mBq l−1. The associated annual effective doses for adults jmrange from 3.5 ± 0.1 to 11.0 ± 0.2 µSv a−1 for 210Po and from 2.0 ± 0.1 to 5.0 ± 0.1 µSv a−1 for 210Pb. The lowest doses were noticed in Kuyavian-Pomeranian Voivodeship and the highest values were found in Lesser Poland Voivodeship. The results show that the annual effective dose in individual provinces is not dangerous to health. However, there are significant differences between highly and lowly industrialized voivodeships.

Uranium analysis in urine after membrane complexation and alpha spectrometry counting

Uranium analysis in urine after membrane complexation and alpha spectrometry counting

Actinide in Air (Rn-Progeny Rejected) Alpha Spectroscopy With Tensioned Metastable Fluid Detectors

Abstract This article discusses outcome of research for deriving a methodology and apparatus for ascertaining for the presence of ultratrace-level actinides in air from their alpha emission signatures, while remaining blind to the relatively large (1000× higher activity) alpha emissions from Rn-progeny. Apparatus and techniques were developed to collect and characterize alpha-emitting nuclides of Rn-progeny and actinides in air on a polycarbonate 3 μm pore size continuous air monitor (CAM) filter. A wet-chemistry approach was developed and validated for successfully separating the Rn-progeny alpha emitting isotopes of Po-214 and Po-218, while extracting the actinides (U, Pu, Am) in a fluid mixture that is suitable for conduct of alpha spectroscopy with a centrifugally tensioned metastable fluid detector (CTMFD). The resulting α-TMFD technology was compared against the state-of-art “Alpha-Sentry™” Continuous Air Monitor (CAM) system commonly utilized world-wide. Results indicate that the α-TMFD technology can potentially offer complementary and superior performance in multiple performance categories, and ∼18× improvement in the time to detect (e.g., at 0.02 derived air concentration (DAC) within ∼3 h, versus ∼70 h for Alpha-Sentry) for actinides of interest while also remaining ∼100% blind to ∼103× higher Rn-progeny background—with the added potential for offering few keV scale energy resolution without resorting to peak shape fitting, versus ∼300–400 keV for existing CAM systems.

Radioactive microparticles related to the Woolsey Fire in Simi Valley, CA

In November 2018, the Woolsey Fire burned north of Los Angeles, CA, USA, potentially remobilizing radioactive contaminants at the former Santa Susana Field Laboratory, a shuttered nuclear research facility contaminated by chemical and radiochemical releases. Wildfire in radiologically contaminated zones is a global concern; contaminated areas around Chernobyl, Fukushima, Los Alamos, and the Nevada Nuclear Test Site have all experienced wildfires. Three weeks after the Woolsey Fire was controlled, sampling of dusts, ashes, and surface soils (n = 360) began and were analyzed by alpha- and beta-radiation counting. Samples were collected up to a 16 km radius from the perimeter of the laboratory. Controls and samples with activities 1σ greater than background were also examined by alpha and/or gamma spectroscopy or Scanning Electron Microscopy with Energy Dispersive X-ray analysis. Of the 360 samples collected, 97% showed activities at or close to site-specific background levels. However, offsite samples collected in publicly-accessible areas nearest to the SSFL site perimeter had the highest alpha-emitting radionuclides radium, thorium, and uranium activities, indicating site-related radioactive material has escaped the confines of the laboratory. In two geographically-separated locations, one as far away as 15 km, radioactive microparticles containing percent-concentrations of thorium were detected in ashes and dusts that were likely related to deposition from the Woolsey fire. These offsite radioactive microparticles were colocated with alpha and beta activity maxima. Data did not support a finding of widespread deposition of radioactive particles. However, two radioactive deposition hotspots and significant offsite contamination were detected near the site perimeter.

Energy calibration of the GEMPix in the energy range of 6 keV to 2 MeV

The GEMPix is a small gaseous detector with a highly pixelated readout, consisting of a drift region, three Gas Electron Multipliers (GEMs) for signal amplification, and four Timepix ASICs with 55 μm pixel pitch and a total of 262,144 pixels (512×512 pixels). A continuous flow of a gas mixture (here propane-based tissue equivalent gas) is supplied externally at a rate of 5 L/h. By placing a sealed 241Am source outside of the detector and varying the source-detector distance, the residual energy of alpha particles entering the sensitive volume of the GEMPix through a thin Mylar window is varied. An alpha spectrometry measurement was performed to determine the emission spectrum of the source, and this spectrum was then used as an input to a FLUKA Monte Carlo simulation to obtain the residual energy of the alpha particles. Thus, a calibration curve from 5.9 keV (from an 55Fe source) up to more than 2 MeV was obtained, which is needed for future applications of the detector, in particular for microdosimetry.

Environmental radioactivity in gold mining in Burkina Faso and potential recycling of mining waste rocks

ABSTRACT Naturally occurring radionuclides have been reported to occur in high concentrations in gold deposits and with other metal ores in Africa. These radionuclides can be released during mining operations and ore processing, causing harmful radiation exposure of mine workers and nearby populations, and may render the mining waste rocks unusable. One large gold mine site in Burkina Faso, near Mana Village, was assessed for naturally occurring radionuclide levels. The area was surveyed for ambient radiation dose rate. Samples from waste rock and sludge from ore milling were analysed by alpha spectrometry, confirming the presence of naturally occurring radionuclides but in relatively low concentrations. It was concluded that mine workers are not exposed to radiation doses significantly above the unmodified natural radiation background. Furthermore, waste rock piles from mining operations can be recycled and used in road construction.