Influence of non-equilibrium and nonlinear sorption of Cs in soils. Study with stirred flow-through reactor experiments and quantification with a nonlinear equilibrium-kinetic model.

This paper addresses the modelling of cesium sorption in non-equilibrium and nonlinear conditions with a two-site model. Compared to the classical K approach, the proposed model better reproduced the breakthrough curves observed during continuous-flow stirred tank reactor experiments conducted on two contrasted soils. Fitted parameters suggested contrasted conditions of cesium sorption between 1) equilibrium sites, with low affinity and high sorption capacity comparable to CEC and 2) non-equilibrium sites, with a fast sorption rate (half-time of 0.

Iodine distribution and volatilization in contrasting forms of forest humus during a laboratory incubation experiment.

Radionuclides I (t = 15.7 × 10 years) and I (t = 8.02 days) are both introduced into the environment as a result of nuclear human activities.

Influence of non-equilibrium sorption on the vertical migration of Cs in forest mineral soils of Fukushima Prefecture.

Sorption hypotheses and models are required for the prediction of Cs migration in soils contaminated after nuclear reactor accidents and nuclear weapons tests. In assessment models, the K (distribution coefficient) hypothesis for sorption, which assumes that sorption is instantaneous, linear and reversible, has often been coupled with the convection-diffusion equation (CDE) to model Cs migration. However, it fails to describe Cs migration velocities which often decrease with time.

Atmospheric iodine, selenium and caesium depositions in France: I. Spatial and seasonal variations.

The spatial distribution and seasonal variations of atmospheric iodine (I), selenium (Se) and caesium (Cs) depositions remain unclear and this precludes adequate inputs for biogeochemical models. We quantified total concentrations and fluxes of these elements in rainfalls from 27 monitoring sites in France with contrasted climatic conditions; monthly measurements were taken over one year (starting in 2016/09). Since speciation of I and Se can impact their behaviour in the environment, analysis of their inorganic compounds was also conducted.

Atmospheric iodine, selenium and caesium depositions in France: II. Influence of forest canopies.

Estimation of the canopy influence on atmospheric inputs of iodine (I), selenium (Se) and caesium (Cs) in terrestrial ecosystems is an essential condition for appropriate biogeochemical models. However, the processes involved in rain composition modifications after its passage through forest canopy have been barely studied for these elements. We monitored I, Se and Cs concentrations in both rainfall and throughfall of fourteen French forested sites throughout one year, and estimated dry deposition and canopy exchange fluxes for these elements, as well as speciation of I and Se.

Impact of drying and wetting cycles on Cs ageing in forest soils contaminated with different input forms.

Water and acetate extractable radiocesium (Cs) concentrations were monitored for >400 days in soils that were amended with aqueous Cs or solid organic sources of Cs (plant litter or fragmented organic materials) and subjected to a series of wet-dry cycles. The soils were collected from broadleaf and cedar forests in Fukushima, Japan. In soils amended with aqueous Cs, the water extractable Cs fraction was very low (<1%) and decreased over time while it was below the detection limit in soils amended with solid organic sources of Cs.

Iodine budget in forest soils: Influence of environmental conditions and soil physicochemical properties.

Due to its longevity, radioisotope I is a health concern following potential releases in the environment which raises questions about residence and exposure times relevant for risk assessments. We determined I concentrations (as a surrogate for I) in a series of French forest soils (i.e.

The impact of radiocesium input forms on its extractability in Fukushima forest soils.

The effects of Cs deposit forms on its ageing in soil have not yet been reported. Soluble and Solid Cs input forms were mixed with the mineral soils collected under Fukushima's coniferous and broadleaf forests, incubated under controlled laboratory, and examined the evolution of Cs availability over time. Results show that the extracted Cs fraction with water was less than 1% for the soluble input form and below detection limit for the solid input forms.

Magnetic resonance imaging changes following natalizumab discontinuation in multiple sclerosis patients with progressive multifocal leukoencephalopathy.

Background: Detecting early progressive multifocal leukoencephalopathy-immune reconstitution inflammatory syndrome (PML-IRIS) is clinically relevant.

Objective: Evaluating magnetic resonance imaging (MRI) changes following natalizumab (NTZ) discontinuation and preceding PML-IRIS.

Methods: MRIs (including diffusion-weighted imaging (DWI), T2-weighted fluid-attenuated inversion recovery (T2-FLAIR), post-contrast T1-weighted sequences) were performed every week following PML diagnosis in 11 consecutive NTZ-PML patients.

Malignant pleural mesothelioma risk among nuclear workers: a review.

Exposure to ionising radiation has been suggested as a causal risk factor for malignant pleural mesothelioma (MPM). Studies of patients treated by radiotherapy for primary cancers have suggested that radiation contributes to the development of secondary MPM. Here we examined the risk to nuclear workers of MPM related to exposure to low doses of occupational radiation at low dose rates.

Characterisation of protracted low-level exposure to uranium in the workplace: A comparison of two approaches.

Retrospective estimates of internal doses received by workers in the nuclear industry following intake of radionuclides, based on bioassay data, are a benchmark method in epidemiological studies. Nonetheless, full information relative to thousands of people included in an epidemiological cohort is rarely available, thus implying difficulties to estimate exposure precisely. To evaluate the cumulative exposure to uranium in a cohort of the AREVA NC Pierrelatte plant workers, we compared the epidemiological Job Exposure Matrix (JEM) method with the dosimetric method based on biological monitoring of exposure for 30 workers randomly selected within the cohort.

Automatic application of ICRP biokinetic models in voxel phantoms for in vivo counting and internal dose assessment.

As part of the improvement of calibration techniques of in vivo counting, the Laboratory of Internal Dose Assessment of the Institute of Radiological Protection and Nuclear Safety has developed a computer tool, 'OEDIPE', to model internal contamination, to simulate in vivo counting and to calculate internal dose. The first version of this software could model sources located in a single organ. As the distribution of the contamination evolves from the time of intake according to the biokinetics of the radionuclide, a new facility has been added to the software first to allow complex heterogeneous source modelling and then to automatically integrate the distribution of the contamination in the different tissues estimated by biokinetic calculation at any time since the intake.

Determination of new European biometric equations for the calibration of in vivo lung counting systems using the Livermore phantom.

New biometric equations used for assessing the thickness of the overlay plate to be added to the physical phantom were determined based on the Computed Tomography (CT) chest images of 33 adult males in order to improve the calibration of in vivo lung counting systems using the Livermore phantom. These equations are specific to systems composed of four germanium detectors with the measured subject in supine position. A comparison with the biometric equations used to date as reference in France was carried out and proved the usefulness of equations directly applicable to the Livermore phantom.