Detecting radioactive particles in complex environmental samples using real-time autoradiography.

Radioactive particles often contain very high radioactivity concentrations and are widespread. They pose a potential risk to human health and the environment. Their detection, quantification, and characterization are crucial if we are to understand their impact.

Improved Radio-Cesium Detection Using Quantitative Real-Time Autoradiography.

Cesium-134 and -137 are prevalent, long-lived, radio-toxic contaminants released into the environment during nuclear accidents. Large quantities of insoluble, respirable Cs-bearing microparticles (CsMPs) were released into the environment during the Fukushima Daiichi nuclear accident. Monitoring for CsMPs in environmental samples is essential to understand the impact of nuclear accidents.

Cantilever-enhanced photoacoustic measurement of HTO in water vapor.

A photoacoustic detection of tritiated water (HTO) is presented. The method uses cantilever-enhanced photoacoustic spectroscopy (CEPAS) to reach sub-ppb sensitivity for HTO in the gas phase. A noise equivalent concentration of 0.

Vadose-zone alteration of metaschoepite and ceramic UO in Savannah River Site field lysimeters.

Uranium dioxide (UO) and metaschoepite (UO•nHO) particles have been identified as contaminants at nuclear sites. Understanding their behavior and impact is crucial for safe management of radioactively contaminated land and to fully understand U biogeochemistry. The Savannah River Site (SRS) (South Carolina, USA), is one such contaminated site, following historical releases of U-containing wastes to the vadose zone.

STED nanoscopy - A novel way to image the pore space of geological materials.

STED nanoscopy (Stimulated Emission Depletion). which can resolve details far below the diffraction barrier has been applied hitherto preferentially to life sciences. The method is however also ideal for the investigation of geological matrices containing transparent minerals, an application tested here, to our knowledge, for the first time.

Quantitative imaging of Ra ultratrace distribution using digital autoradiography: Case of doped celestines.

The ability of the autoradiographic device BeaQuant™ is evaluated herein to quantitatively map the ultratrace element Ra distributed spatially in celestine (SrSO) grains/crystals. Ra doped celestines have been obtained from coprecipitation and recrystallization experiments, and have been characterized with high purity germanium gamma detector (HPGe), giving specific activities ranging from 3251 to 32523 Bq.g.

Development and application of an advection-dispersion model for data analysis of electromigration experiments with intact rock cores.

An advection-dispersion model was developed for interpreting the experimental results of electromigration in granitic rock cores. The most important mechanisms governing the movement of the tracer ions, i.e.

A modification of the electromigration device and modelling methods for diffusion and sorption studies of radionuclides in intact crystalline rocks.

To determine the diffusion and sorption properties of radionuclides in intact crystalline rocks, a new electromigration device was built and tested by running with I and Se(IV) ions. By introducing a potentiostat to impose a constant voltage over the studied rock sample, the electromigration device can give more stable and accurate experimental results than those from the traditional electromigration devices. In addition, the variation in the pH of the background electrolytes was minimised by adding a small amount of NaHCO as buffers.

Sorption of selenium species onto phlogopite and calcite surfaces: DFT studies.

Sorption of Se(IV) and Se(VI) species onto Mg-rich biotite (phlogopite) and calcite surfaces was investigated using molecular modelling techniques. A CASTEP code implemented into Materials Studio was used to calculate the periodic systems, site densities and site types on the phlogopite and calcite surfaces. According to the results, the Se oxyanions attach to both edge and basal surfaces of phlogopite via an oxygen atom.

Electronic autoradiography of Ba particle emissions; diffusion profiles in granitic rocks.

The spatial distribution of barium activity in granitic rocks was measured with two autoradiography techniques; digital autoradiography using phosphor imaging plate technique (Fuji 5100) and filmless electronic autoradiography (i.e. The BeaQuant™), which is based on a gas detector incorporated in a micromesh Parallel Ionization Multiplier (PIM).

Through diffusion experiments to study the diffusion and sorption of HTO, Cl, Ba and Cs in crystalline rock.

The spent nuclear fuel in Finland will be deposited in crystalline granitic rock in Olkiluoto, Finland. As a part of the safety assessment of the repository, series of extensive in-situ sorption and diffusion experiments and supplementary laboratory work has been done in the Olkiluoto site. Through Diffusion Experiment in a laboratory (TDElab) aims to provide applicable data for the ongoing in-situ experiment in Olkiluoto.

Mapping U decay chain equilibrium state in thin sections of geo-materials by digital autoradiography and microprobe analysis.

A new approach is proposed in order to spatially localize and determine the equilibrium state of natural decay chains on hand-scale geological samples, thanks to a combination of three techniques: 1) Elementary chemical mapping by microprobe; 2) Alpha autoradiograph by gaseous detectors and 3) bulk alpha particle spectrometry. The quantitative nature of alpha autoradiograph and its comparison with U chemical maps allows to locate radioactive equilibrium state in four samples. This equilibrium state was confirmed by alpha spectrometry analysis.

Radon emanation from fresh, altered and disturbed granitic rock characterized by C-PMMA impregnation and autoradiography.

Radon emanation from intact samples of fresh ("BG"), altered ("Fract") and disturbed ("EDZ") Finnish granitic rock from Kuru (Finland) and its dependence on humidity and rock structural factors was studied. The pore network of the rock was characterized by microscopy and impregnation with C-PMMA (polymethylmethacrylate) resin and autoradiography. The radon emanation factor was increasing linearly with the relative humidity.

Sorption and diffusion of selenium oxyanions in granitic rock.

The processes controlling diffusion and sorption of radionuclides have been studied extensively in the laboratory, whereas, only a few in-situ experiments have been carried out in order to study in-situ diffusion over the long-term (several years). This is largely due to the fact that in-situ experiments are typically time consuming and cost intensive, and it is commonly accepted that laboratory scale tests are well-established approaches to characterizing the properties of geological media. In order to assess the relevance of laboratory experiments, the Swiss National Cooperative for Disposal of Radioactive Waste (Nagra) have been conducting extensive experiments in the Underground Rock Laboratory (URL) at the Grimsel Test Site (GTS) in order to study radionuclide transport and retention in-situ.

Comparative modeling of an in situ diffusion experiment in granite at the Grimsel Test Site.

An in situ diffusion experiment was performed at the Grimsel Test Site (Switzerland). Several tracers ((3)H as HTO, (22)Na(+), (134)Cs(+), (131)I(-) with stable I(-) as carrier) were continuously circulated through a packed-off borehole and the decrease in tracer concentrations in the liquid phase was monitored for a period of about 2years. Subsequently, the borehole section was overcored and the tracer profiles in the rock analyzed ((3)H, (22)Na(+), (134)Cs(+)).

Airborne fission products in the High Arctic after the Fukushima nuclear accident.

High-volume aerosol samples were collected at the Mt. Zeppelin Global Atmosphere Watch station, Ny-Ålesund, Svalbard (78°58'N, 11°53'E). The samples were analysed to find out if the radionuclide emissions from the Fukushima nuclear power plant accident in March 2011 could be detected also in the atmosphere of the High Arctic.

Analysis of 18F-labelled synthesis products on TLC plates: comparison of radioactivity scanning, film autoradiography, and a phosphoimaging technique.

We compared radioactivity scanning, film autoradiography, and digital photostimulated luminescence (PSL) autoradiography (phosphoimaging technique) in detection of radioactivity on thin-layer chromatography (TLC) plates. TLC combined with radioactivity detection is rapid, simple, and relatively flexible. Here, (18)F-labelled synthesis products were analyzed by TLC and the radioactivity distribution on the plates determined using the three techniques.