Inter laboratory comparison for

241Am is an alpha emitter which originates from the successive neutron capture reactions by plutonium isotopes in a nuclear reactor: [math]. Activation products like 241Am may contribute significantly to human exposure in case of an accidental release in the environment. Therefore, this isotope is monitored together with plutonium isotopes in environmental matrices near nuclear facilities. In addition, because of its 241Pu filiation, contribution of 241Am in the environment will increase in future years. 241Am in sands was measured by three different techniques: direct gamma ray spectrometry, alpha spectrometry and sector field ICP-MS. Prior to alpha and ICP-MS measurements by isotope dilution, americium was separated from major components of the matrix and other transuranic elements by anion exchange and extraction chromatography. The results of two different laboratories are compared

Plutonium, protactinium, uranium and thorium isotopes determination in environmental samples by SF ICP-MS

International audienc

Optimisation de la mesure urinaire des émetteurs bêta par scintillation liquide à résolution temporelle

La scintillation liquide est une méthode d’analyse de choix du suivi radio toxicologique des travailleurs susceptibles d’être exposés à des sources émettrices β purs. Les éléments étant présents à l’état de traces dans les urines, il est nécessaire d’optimiser la technique de mesure afin d’obtenir la meilleure sensibilité. Ces dernières années ont vu apparaître des nouvelles générations de liquides scintillants, moins polluants et moins toxiques, destinés à remplacer les liquides scintillants traditionnels. Ces scintillants dits de « nouvelle génération » possèdent cependant un inconvénient technique à leur utilisation : une dissipation plus longue de l’énergie émise par le photon de fluorescence résultant de l’interaction entre le milieu scintillant et le rayonnement. Ce phénomène a un impact direct sur la qualité de la détection et amène à rechercher une valeur du Delay Before Burst optimale qui permette de distinguer les signaux du rayonnement de la source à mesurer, de ceux venant du milieu environnant. Cette étude vise à montrer l’importance du choix de la valeur du paramètre Delay Before Burst dans l’optimisation des limites de détection pour les mesures en scintillation liquide. L’influence de ce paramètre a été étudiée sur les différents radionucléides mesurés au Laboratoire d’Analyses Médicales Radiotoxicologiques (LAMR) de l’Institut de Radioprotection et de Sureté Nucléaire (IRSN); le 3H, le 14C et le 89Sr. Notre étude compare les rayonnements β mesurés avec un liquide scintillant traditionnel : le Pico-Fluor 40 et un liquide scintillant de nouvelle génération : l’Ultima Gold LTT

Cellular dosimetry of strontium-90 using the Monte Carlo code MCNPX, detection and X-ray microanalysis

The aim of this study is to provide data that increase knowledge about the possible health effects of exposure to 90Sr contaminant in drinking water. 90Sr detection in the mouse bone model plays an important complementary role with computational dosimetry in these investigations. S-value (absorbed dose per unit cumulated activity) calculations using Monte Carlo (MC) simulations, 90Sr detection by liquid scintillation β counting in the femur bone and X-ray microanalysis were carried out. The present work is focused on using MCNPX and its validation at a cellular level. The cytoplasm (Cy), nucleus (N) and 90Sr radiation source were simulated with the MC code MCNPX. Cells are assumed to be spherical, with the radii of the cell and cell nucleus ranging from 2 to 10 μm. The S-value (in Gy/Bq.s) calculations were provided for a 90Sr source distributed uniformly in the cell nucleus or cytoplasm and for two source-target combinations (t←s). A comparison between the calculated MC results and the MIRD values agreed very well since the relative deviations are less than 4%. The earliest results of X-ray microanalysis indicated that the 90Sr was below the detection limit (<0.1%) in the bone tissue. However, the measurements by liquid scintillation showed the presence of 90Sr in the femur bone

High levels of natural radioactivity in biota from deep-sea hydrothermal vents: a preliminary communication

Hydrothermal deep-sea vent fauna is naturally exposed to a peculiar environment enriched in potentially toxic species such as sulphides, heavy metals and natural radionuclides. It is now well established that some of the organisms present in such an environment accumulate metals during their lifespan. Though only few radionuclide measurements are available, it seems likely that hydrothermal vent communities are exposed to high natural radiation doses. Various archived biological samples collected on the East Pacific Rise and the Mid-Atlantic Ridge in 1996, 2001 and 2002 were analysed by ICP-MS in order to determine their uranium contents (238U, 235U and 234U). In addition 210Po-Pb were determined in 2 samples collected in 2002. Vent organisms are characterized by high U, and Po-Pb levels compared to what is generally encountered in organisms from outside hydrothermal vent ecosystems. Though the number of data is low, the results reveal various trends in relation to the site, the location within the mixing zone and/or the organisms' trophic regime. © 2009 Elsevier Ltd. All rights reserved

Intracellular uranium distribution : Comparison of cryogenic fixation versus chemical fixation methods for SIMS analysis

International audienceLocalization of uranium within cells is mandatory for the comprehension of its cellular mechanism of toxicity. Secondary Ion Mass Spectrometry (SIMS) has recently shown its interest to detect and localize uranium at very low levels within the cells. This technique requires a specific sample preparation similar to the one used for Transmission Electronic Microscopy, achieved by implementing different chemical treatments to preserve as much as possible the living configuration uranium distribution into the observed sample. This study aims to compare the bioaccumulation sites of uranium within liver or kidney cells after chemical fixation and cryomethods preparations of the samples SIMS analysis of theses samples show the localization of uranium soluble forms in the cell cytoplasm and nucleus with a more homogenous distribution when using cryopreparation probably due to the diffusible portion of uranium inside the cytoplasm. © 2018 The Authors. Microscopy Research and Technique Published by Wiley Periodicals, Inc