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The Rhone River is one of the most nuclearized river in the world. Radionuclide concentrations in water and suspended sediments transferred to the marine environment were intensively monitored in this river over the last decades (2002–2018). Over this period of time, >12 and 25 time integrating samples were collected each year in filtered waters and suspended sediments, respectively, and analyzed for their radionuclide contents at ultra-trace levels by using top performance analytical tools. While >60% of plutonium, americium, cesium, cobalt, silver, beryllium and actinium radioisotopes are carried by sedimentary particles, sodium, tritium, antimony and strontium are mainly exported as dissolved species (>90%) due to their low affinity with particles. Most natural radionuclides contents show low seasonal variation. No significant trends are observed over the last two decades for these elements, even for 40K widely used in fertilizers after the middle of the last century, indicating that the basin has currently converged towards geochemical equilibrium for all of them. In contrast, the concentrations of numerous anthropogenic radionuclides originating from nuclear industries significantly declined since the beginning of the 2000s. Assuming no change of the current anthropic and climatic pressures over the next decades, apparent periods, i.e. the time required for a reduction by half the concentrations in the downstream part of the Rhone River, would be close to 6 years for most artificial radionuclides, except for tritium and other artificial radionuclides conveyed to the river by soil leaching and erosion (90Sr, 241Am, plutonium isotopes) which would be far longer. Referring to regional referential backgrounds, only few anthropogenic radionuclides specifically produced by nuclear industries are still detectable at the downstream part of the Rhone River and excess contents of tritium, 238Pu and 241Am are observed in filtered waters.

International audience; This paper presents a new gamma-gamma coincidence spectrometer to measure the radioactivity in environmental samples. This system, called Leda, is made of 2 HPGe and 1 NaI(Tl). The different analysis channels (single, in coincidence or in anti-coincidence) possible thanks to the digital electronics are described. Results obtained with environmental samples are shown. Despite its low efficiency, this method improves the detection limits for all emitters due to its very low background, and thus decreases the counting time.

Tritium of artificial origin was initially introduced to the environment from the global atmospheric fallout after nuclear weapons tests. Its level was increased in rainwaters by a factor 1000 during peak emissions in 1963 within the whole northern hemisphere. Here we demonstrate that tritium from global atmospheric fallout stored in sedimentary reservoir for decades as organically bound forms in recalcitrant organic matter while tritium released by nuclear industries in rivers escape from such storages. Additionally, we highlight that organically bound tritium concentrations in riverine sediments culminate several years after peaking emission in the atmosphere due to the transit time of organic matter from soils to river systems. These results were acquired by measuring both free and bound forms of tritium in a 70 year old sedimentary archive cored in the Loire river basin (France). Such tritium storages, assumed to be formed at the global scale, as well as the decadal time lag of tritium contamination levels between atmosphere and river systems have never been demonstrated until now. Our results bring new lights on tritium persistence and dynamics within the environment and demonstrate that sedimentary reservoir constitute both tritium sinks and potential delayed sources of mobile and bioavailable tritium for freshwaters and living organisms decades after atmospheric contamination.

International audience; A new protocol designed for the rapid determination of U, Th, Pu, Np, Am and Sr in up to 500 mL of river water samples has been developed. The new method employs chromatographic separation, using TEVA, TRU and Sr resins, coupled to an inductively coupled plasma mass spectrometry and to a gas proportional counting (GPC). Excellent figures of merit characterized by recoveries and accuracies exceeding 80 and 90 %, respectively and detection limits below emergency thresholds are obtained. The new GPC methodology for the quantification of radiostrontium led to accurate results even with activity ratios (A89Sr/A90Sr) as high as 95. © 2016, Akadémiai Kiadó, Budapest, Hungary.

International audience; The data on 210Pb and 210Po activities in French foodstuffs acquired during the last 15 years are numerous enough to derive reference values which will be usable to assess the dose to the French population due to the intake of these two natural radionuclides. The means and ranges are close to those observed in various countries and are most often higher than the reference values proposed by UNSCEAR. Mussels and oysters exhibit the highest 210Po activities of all kinds of foodstuffs, with a mean value of 27 Bq.kg-1 fresh weight, followed by crustaceans and small fish species (anchovies, mullets, sardines, etc.) with 210Po activities in the order of 3 to 10 Bq.k-1 fresh weight; cephalopods and other fish species presenting activities around 1 to 3 Bq.kg-1 fresh, close to the UNSCEAR reference value. Below these highest 210Po activities are those of 210Po and 210Pb in terrestrial kinds of foodstuffs, by decreasing order meats (around 1 Bq.kg-1 fresh), cereals (0.4 Bq.kg-1), leafy vegetables (0.3 Bq.kg-1), other vegetables and fruits (0.1 Bq.kg-1), and milk (from 0.03 to 0.1 Bq.L-1). © 2015 EDP Sciences.

International audience; The activities of 228Ac and 214Bi in French foodstuffs acquired during the last 15 years allow one to obtain reference values of 228Ra and 226Ra activities which are usable to assess the dose to the French population due to the intake of these two natural radionuclides. As expected, because of similar 238U and 232Th activities in French soils (around 40 Bq.kg-1), the 226Ra/228Ra activity ratio in French terrestrial foodstuffs is close to 1. Most kinds of foodstuffs present similar mean activities from 0.1 to 0.2 Bq.kg-1 fresh for cereals, leafy vegetables, root vegetables, eggs and fishes (marine and freshwater). The activity in fruits is lower, around 0.05 Bq.kg-1, similar to that of meat calculated on the basis of the numerous grass measurement results. The lowest activities are noticeable for milk around 0.015 Bq.L-1. All these values are in good agreement with the data from various countries, but most often 2 to 3 times higher than the reference values proposed by UNSCEAR. This study also shows that due to the large variability of foodstuff activities reported by a large amount of data, it is not possible to distinguish the activities of samples from regions with a gap of only a factor of 2 between their soil activities. © 2015 EDP Sciences.

International audience; A new protocol for the rapid quantification of actinides (U, Th, Pu, Am and Np) and 90Sr in soil samples has been developed. This protocol includes three steps (1) an alkaline fusion digestion, (2) an automated separation and (3) an on-line ICP-MS measurement. Eluted fraction containing strontium can be collected to quantify radiostrontium using off-line radiometric techniques. After an optimization of the separation protocol using a design of experiments, excellent figures of merit are achieved. These figures include high chemical recoveries (andgt;80%) for all radionuclides investigated, low quantification limits for actinides and concordance between measured activities and reference values. This protocol allows the automated treatment (sample dissolution included) of up to 10 samples in 24 h. © 2017, Akadémiai Kiadó, Budapest, Hungary.

National audience; In many places in the world, canals represent a significant cumulative linear effect on the flow of surface waters and play a significant role in the redistribution of water resources. A radioecological study was conducted on the Languedoc Roussillon regional Rhodanian canals which transfer water from the river Rhône to the territories of the Gard and Herault for irrigation and drinking water supply. Our results show that the hydrological characteristics of water canals may impact significantly on the solid/solution distribution of trace elements in transit, and consequently on their transfer to the receiving environment. In addition to particle size segregation during transit, these results are most likely to be related to biological production (phytoplankton and zooplankton). These results highlight that the origin and quality of naturally occurring solid particles could play a fundamental role in the transfer of trace pollutants, especially in irrigation canals. © 2014 EDP Sciences.; Une étude radioécologique a été menée sur les canaux rhodaniens du réseau hydraulique régional propriété de la région Languedoc Roussillon, gérés par BRL. Ces canaux transfèrent de l’eau du fleuve Rhône vers les territoires des départements du Gard et de l’Hérault à des fins d’irrigation et de production d’eau potable. Nos résultats montrent que les caractéristiques hydrauliques intrinsèques des canaux de transport d’eau influent sur la distribution solide/solution des éléments traces en transit et par conséquent sur leur transfert vers les milieux récepteurs. Si les concentrations en phase dissoute (eau filtrée) sont conservées, les concentrations en phase particulaire (matières en suspension et sédiments) sont significativement modifiées au cours du transit. Outre la ségrégation granulométrique des particules entre l’amont et l’aval du système, ces résultats sont très probablement liés à la production biologique autochtone (phyto et zooplancton). Ces résultats originaux soulignent le caractère atypique des canaux de transport d’eau quant au transfert des éléments potentiellement contaminants.

Afin d’evaluer les consequences des rejets radioactifs provenant des reacteurs accidentes de la centrale nucleaire de Fukushima-Daichi sur l’environnement terrestre francais, l’IRSN a renforce son plan de surveillance en echantillonnant notamment de la vegetation de prairie, du lait et de la viande des troupeaux en pâture entre avril et novembre 2011. Ces prelevements et ces mesures ont, entre autres, permis d’evaluer dans des conditions de depots reels la chronologie des transferts du cesium-134 de l’herbe au lait et a la viande. Les premieres mesures significatives en 134 Cs apparaissent dans l’herbe et dans le lait cinq a sept jours apres la premiere mesure significative dans l’air. Les activites maximales atteignent 0,4 Bq.kg–1 d’herbe fraiche et 0,028 Bq.L–1 dans le lait. Dans la viande, les premieres mesures significatives apparaissent mi-avril avec une activite maximale mesuree de 0,036 Bq.kg–1 , avec de fortes variations d’une espece animale a une autre. Les coefficients de transfert moyens calcules sont proches de ceux disponibles dans la litterature avec 0,22 j.kg–1 pour la viande de mouton, et de 0,09 et 0,0014 j.L–1 pour le lait de chevre et de vache, respectivement.

et al., The preparation and characterization of certified reference materials (CRMs) for radionuclide content in sediments collected offshore of Bikini Atoll (IAEA-410) and in the open northwest Pacific Ocean (IAEA-412) are described and the results of the certification process are presented. The certified radionuclides include: 40K, 210Pb (210Po), 226Ra, 228Ra, 228Th, 232Th, 234U, 238U, 239Pu, 239+240Pu and 241Am for IAEA-410 and 40K, 137Cs, 210Pb (210Po), 226Ra, 228Ra, 228Th, 232Th, 235U, 238U, 239Pu, 240Pu and 239+240Pu for IAEA-412. The CRMs can be used for quality assurance and quality control purposes in the analysis of radionuclides in sediments, for development and validation of analytical methods and for staff training.

Iodine-131 and various other radionuclides were released into the atmosphere from the damaged Japanese reactors of Fukushima Dai-ichi from 12 to 22 March 2011. The contaminated air mass was detected in France after 24 March; samples of grass, vegetables, and milk have been analyzed for (131)I by the IRSN, considering the fact that few values of iodine-131 transfer parameters have been directly measured in situ, due to the radioactive decay of this isotope. Data are compared with calculated values according to the air iodine concentration. The apparent dry deposition velocity of iodine on grass is therefore estimated to range between 1 × 10(-3) and 5 × 10(-3) m s(-1) from site to site. In addition, the grass to milk transfer factors are 2.8 × 10(-2) and 3.6 × 10(-3) d L(-1) for goat's and cow's milk respectively. These parameters fit well with the current values usually considered for radioecological assessment.

La concentration de l’environnement francais en radionucleides artificiels et les techniques d’analyses ont considerablement evolue au cours des 50 dernieres annees. Au cours des annees 60 et 70, la surveillance effectuee par l’Institut de protection et de surete nucleaire (IPSN) et par le service central de protection contre les rayonnements ionisants (SCPRI) permettait de connaitre les niveaux des radionucleides artificiels les plus abondants et qui contribuaient de facon preponderante aux doses recues par la population francaise. Depuis les annees 80, avec la fin des essais atmospheriques d’armes nucleaires et la baisse des activites de la plupart des radionucleides concernes, les radionucleides devenus preponderants en activite et en doses sont : 3 H, 14 C, 85 Kr et 133 Xe. Or ces quatre radionucleides ne font aujourd’hui l’objet que d’un nombre tres restreint d’analyses dans le cadre de la surveillance effectuee par l’IRSN. La mise en relation des niveaux d’activite des radionucleides constituants le « bruit de fond » de la radioactivite artificielle environnementale, des activites potentiellement ajoutees du fait des rejets des installations nucleaires, des doses correspondantes, ainsi que des limites de detection obtenues au moyens des meilleures techniques disponibles, fournit des elements de reflexion sur les enjeux de la surveillance radiologique de l’environnement et sur les possibilites d’atteindre les objectifs correspondants. A l’exception de 14 C et 3 H, les activites les plus basses presentes dans l’environnement se trouvent d’ores et deja au niveau ou en-deca des limites de detection des techniques de mesure. 3 H et 14 C sont donc les seuls radionucleides toujours mesurables dans l’environnement et pour lesquels une influence des rejets atmospheriques des installations nucleaires est potentiellement decelable dans tous les milieux.

The results of the low-level performance of an anti-Compton device are presented. The anti-coincidence action of the NaI detectors lowers the total background of the HPGe detector integrated on the energy range 30 keV to 2730 keV by a factor 8.1 and suppresses the continuum above 300 keV by a factor larger than 10. Qualitative and quantitative results on environmental samples are described to illustrate the improvement of uncertainties determination and the significant reduction of detection limits. This provides ever more accurate and precise data on natural and anthropogenic radionuclides often used as tracers for environmental studies.

Airborne 137 Cs level in France is not decreasing significantly anymore (mean yearly value around 0,25 µ Bq.m-3 contrarily to what was noticed in the past decades. This observation points out the role of processes that delay the atmospheric cleaning and participate to the persistence of radionuclide in the air at ground-level after a deposit, in the frame of medium as well as long-dated post-accidental contexts. The current background level also yields to consider 137 Cs in the atmosphere as a tracer of atmospheric processes like resuspension and re-emission from biomass burnings. This allows us to explain 2/3 of the peaks observed over the last six years. The remaining 1/3 is mainly noticed in winter when spreading of pollutants in the atmosphere is often weak due to temperature gradient inversion. On average, continental air masses are responsible for increases by a factor of 3 while oceanic air masses are characterised by levels 3 times lower, compared to the mean value. Feeding of 137 Cs in air at ground-level is the result of both local resuspension that signs 137 Cs activity levels in soils to which is added a remote contribution from time to time (resuspension of Saharan dust or re-emission from fires occurring in eastern territories with high 137 Cs deposition level). Finally, 137 Cs activity levels in air masses crossing over France can be described on average by a longitudinal gradient.

International audience; This paper presents the latest development of the laboratory to measure the natural and artificial massic activities in environmental samples. The measurement method of coincident emitters by gamma–gamma coincidence using an anti-Compton device and its digital electronics is described. Results obtained with environmental samples are shown. Despite its low efficiency, this method decreases detection limits of 60Co for certain samples compared to conventional gamma-ray spectrometry due to its very low background.

International audience; Airborne cesium isotopes (134Cs and 137Cs) released during the Fukushima nuclear accident were transported all around the world attached to particles and reached France about 12 days after the first explosion. Concentration of cesium isotopes in cloud water sampled at the summit of the Puy de Dôme mountain (1465 m a.s.l.) increased by a factor of at least 40. During the following weeks, the concentrations decreased more slowly in cloud water than in rain and in rain compared with what was found on the aerosol phase. Cesium-134 was detectable in the aerosol phase, in rain and in cloud water for 3 months, 11 months and 18 months after the accident, respectively. These kinetics are consistent with the washout scavenging of aerosol in the lower layers of the atmosphere that leads to a relative depletion of Fukushima-labeled aerosols at ground level. Airborne particles at high altitudes, i.e. where clouds form, have a longer residence time. This finding has implications on the different time scales at which a contamination may be transferred to the ground, depending if it is transferred via dry or wet deposition. This study highlights that cloud water is a relevant type of environmental sample to attest the presence of radionuclides on a longer time scale than for the aerosol phase, provided that the metrology is able to lower usual detection limits. Rainout efficiency was computed for 137Cs.

In the frame of IRSN's French radioactivity observatory, aerosol samples are collected in a ten-days basis in different locations and measured by gamma spectrometry. For some studies, it is necessary to have the average of a radionuclide in aerosol samples, i.e. monthly or annually. Gamma spectrometry measurement of artificial radionuclides such as 137 Cs is becoming more difficult due to decreasing radioactivity levels. Individual measurements are sometimes below the minimum detectable activity (MDA) even when low-background measurement procedures are used. In these cases, how can a MDA in an average computation be taken into account? In order to acquire this mean value, the analysis can be performed on the annual spectrum corresponding to a running sum of each individual spectrum. As for the sample, the summing is applied for the background spectrum. In this way, the 137 Cs concentration in aerosols corresponding to the annual mean value is obtained. For aerosols collected in La Reunion, a mean concentration of 0.029 ± 0.010 µBq.m -3 for 137 Cs is obtained, when 25 measurement results on 26 samples are below the MDA. For radionuclides always detected, a good agreement between summing spectrum results and computed mean value is observed.

Les techniques employees pour quantifier les emetteurs beta purs (3 H, 14 C, 90 Sr, 36 Cl, 63 Ni…) dans les matrices environnementales sont basees sur une selectivite physico-chimique de l’element suivi d’une mesure par scintillation liquide ou comptage proportionnel. Nous avons etudie une configuration de mesure simple, basee sur des detecteurs silicium minces (PIPS), afin d’obtenir une selectivite spectrometrique couplee ou non a une selectivite physico-chimique. La quantification de sources pures montre que les limites de detection sont du meme ordre de grandeur que celles obtenues par les methodes conventionnelles avec l’avantage de preciser la presence d’interferents residuels. De meme, pour des mesures de surveillance ou de controle reglementaire, excluant une preparation chimique importante, la contribution des radionucleides naturels est souvent a la base de la mise en œuvre de mesures complementaires. Cette contribution des naturels peut etre observee afin d’exclure la necessite de ces mesures complementaires meme si les seuils globaux reglementaires sont depasses.

Les longues series temporelles d'observation de la radioactivite dans l'atmosphere (au niveau du sol) permettent d'etudier l'evolution de ce reservoir apres les injections des experimentations nucleaires militaires, de l'activite industrielle, ou suite aux accidents tel que celui de Tchernobyl (1986). Conjointement a l'observation des radionucleides d'origine artificielle, les radionucleides formes par l'interaction du rayonnement cosmique dans la haute atmosphere, comme 7 Be, sont quantifies. La correlation entre les composantes naturelles et artificielles permet de mieux comprendre l'evolution globale de la radioactivite dans l'atmosphere. L'observatoire de la radioactivite dans l'atmosphere de l'Institut de radioprotection et de surete nucleaire (IRSN) a debute en 1959. Actuellement les aerosols sont preleves dans 6 stations localisees en Metropole et dans 2 stations en Outre-mer (hemisphere sud). Les concentrations de 137 Cs dans les aerosols en 2002 sont de l'ordre de 0,4 μ Bq m-3 en metropole et 10 fois moins a Tahiti. Les activites du 7 Be, de l'ordre de 3 200 μ Bq m-3 , sont similaires en metropole et a Tahiti.

A very large ( 903 cm 3 , 4.8 kg of Ge) ultra-low background well-type Ge detector has been installed in the Modane underground laboratory. This device is currently used in environmental studies, when only small samples are available and containing low levels of radioactivity. The main characteristics of the spectrometer will be presented. The calibration procedure—a mixture of experimentally measuring the photon attenuation of the sample matrix and Monte Carlo simulations using GEANT and the DECAY code—will be described.

A large-scale international in situ intercomparison measurements has been organized in the "Nord-Cotentin" (France) area, in the vicinity of la Hague reprocessing plant and the Nuclear power station of Flamanville. Eleven European countries participated in this event organized at the initiative of the local association "Les Meres en Colere". Two main goals were considered for this event : - An international in situ measurements intercomparison. The general aim of the measurements is to characterise as detailed as possible examined areas regarding their actual radiological standpoint. The basic measurements concerned dose rate, in situ gamma ray spectrometry and laboratory analyses on environmental samples. - A specific aim consisting in providing the local population with an opportunity for direct exchange with international teams. Both aspects will be reported in this paper.

The NEMO-2 tracking detector located in the Frejus Underground Laboratory was designed as a prototype for the NEMO-3 detector and to study different modes of double beta decay. Measurements with 100 Mo, 116 Cd, 82 Se and 96 Zr were carried out. Presented here are the experimental half-life limits on double beta decays for new Majoron emission modes and limits on effective neutrino–Majoron coupling constants.

We apply the self-consistent renormalized proton-neutron QRPA (RQRPA) method to calculate the two-neutrino double beta (2νββ) decay matrix elements associated with the ground-state and excited-state transitions of the 82Se → 82Kr decay. The RQRPA method is an extension of the pnQRPA method and promotes the Pauli exclusion principle violated by the pnQRPA ground state and yields more stable nuclear matrix elements with increasing strength of the proton-neutron interaction. In the present work the RQRPA wave functions are also used to evaluate 2νββ-decay rates to excited final states. The resulting theoretical half lives are compared with the new stringent experimental limits obtained by using a HPGe detector and external sources of enriched selenium.

International audience; Cloud water was sampled during 8 months, in 2008 and 2009, at the puy de Dome high-altitude atmospheric research station (France). The concentrations of 7Be and 210Pb, both naturally occurring radionuclides, and 137Cs of anthropogenic origin, were determined. Those values are useful for a better knowledge of the aftermath cloud deposition and more generally for wet deposition assessment of radionuclides. This is of primary interest in case of a nuclear accident, especially considering 137Cs deposition, both for high-altitude locations that are regularly embedded by clouds and also for lowlands where fog can occur.The 7Be and 210Pb average activity concentrations in cloud water found were 1.9±0.11mBqm-3 air and 140±10μBqm-3 air, respectively. For 137Cs, the average concentration was 0.14±0.02μBqm-3 air. This very low-level is representative of the long term post-accidental background level. Indeed, for the studied period, the last accidental 137Cs release was that of Chernobyl accident, in April 1986. To our knowledge this is the first data about 137Cs reference level determination in cloud water. The comparison between cloud water and rain water concentrations showed a ratio cloud/rain ranging between 3.4 and 8.1, in agreement with previous studies performed on inorganic compounds. Scavenging efficiencies of aerosols by cloud droplets were also calculated with the additional aerosol concentrations routinely measured at the station and were quite low (0.13-0.40) compared to what has previously been observed for inorganic soluble ions. © 2013 Elsevier Ltd.

International audience; The nuclear accident of Fukushima Dai-ichi (Japan) which occurred after the tsunami that impacted the northeast coasts of Japan on March 11th, 2011 led to significant releases of radionuclides into the atmosphere and resulted in the detection of those radionuclides at a global scale. In order to track airborne radionuclides from the damaged reactors and to survey their potential impact on the French territory, the French Institute of Radiation Protection and Nuclear Safety (Institut de Radioprotection et de Sureté Nucléaire IRSN) set up an enhanced surveillance system to give quick results as needed and later give quality trace level measurements. Radionuclides usually measured at trace levels such as 137Cs and in a very sporadic way 131I were reported. Radionuclides that we had never measured in air since the Chernobyl accident 134Cs, 136Cs, the mother/daughter pairs 129mTe-129Te and 132Te-132I, and 140La (from the mother-daughter pair 140Ba- 140La) were also reported. Except the 131I/137Cs ratio, activity concentration ratios were constant. These ratios could be used to help source term assessment, or as data for transfer studies realized after the passage of contaminated air masses, typically using the 134Cs/137Cs ratio. © 2013 Elsevier Ltd.

The two-neutrino mode of double beta decay of is investigated both theoretically and experimentally. The calculations, using the quasiparticle random phase approximation approach, show that for the detection of transitions to the two first excited states in the daughter nuclide will be possible in the very near future. On the experimental side, new, most stringent limits on half-lives for the double beta decay of to excited states in have been obtained with a `well-type' germanium detector. They range between and years (90% CL).

International audience; This paper analyzes the relationship between bank sediment storage and radionuclide content in six alluvial sites located in different geomorphic contexts along the lower Rhône River. The 137Cs, 238Pu, 239+240Pu, 241Am and 210Pb profiles show different patterns, which indicates a differential storage of contaminated sediment in the banks. Three sites record historical nuclear releases in the river and give evidence for long-term retention of particle-reactive long-lived radionuclides. Two sites record only atmospheric global fallout. Only one site, connected to the river groundwater, provides some evidence for desorption of particle-bound contaminants, with a low and constant 137Cs activity profile. The history of the releases from the Marcoule spent-fuel reprocessing plant-the main source of artificial radioactivity-provides a reliable chronology of the last 50 years. Sediment grain size and bank topography are important factors in determining where artificial radionuclides are stored, but these two parameters cannot be used alone to determine variations in high concentrations of radionuclides. The chronology of fluvial geomorphic "metamorphosis" during the twentieth Century, especially after 1960, is also a critical factor affecting the spatial variability in sedimentation rates and artificial radionuclide storage; the timing of channel deepening and bank sedimentary accretion interfere with the chronology of major floods and the short period of low discharge during the height of contamination from nuclear liquid effluents. The reach-scale adjustment described in this paper can contribute to determining what the local history may have been. This result has important implications for river management decisions. © 2012 Springer Basel AG.

International audience; Trace metals (Cu, Cd, Cr, Ni, Pb, Zn, Hg) and artificial radionuclides (Cs-137, Am-241, Pu-238, and Pu239 + 240) were investigated in overbank sediments located in inter embankment areas of the lower Rhone River. Enrichment factors (EF) and anthropogenic factors (AF) were calculated to estimate the level of contamination in these sediment storages. The results show that in the studied sites Co, Ni and Sc display low EF values and are mainly from lithogenic origin. For the other studied trace metals a great variability of sedimentary record is observed. Significant anthropogenic enrichment was highlighted at a particular site that undergoes fluvial inputs occurring in the last 50 years. Lead is the element with the highest EF values (EF = 13), followed by Cd (EF = 11), Cu (EF = 5), Hg (EF = 7), and Zn (EF = 2). Temporal variations of Pb, Cd and Hg show a maximum in the 1960's and a decreasing trend afterward. Maximum enrichment of artificial radionuclides were observed in sediment deposit during the period 1960-1990 when maximum liquid releases from nuclear activities occurred. These results indicate that despite the high-energy conditions and the generally sandy nature of the riverbank sediments, significant anthropogenic enrichments were observed in some areas of sediment accumulation in the lower Rhone River. These enrichments are however relatively low compared to some other rivers in France and Europe due to the important suspended sediment discharge in this River, in particular during strong floods, which dilutes the anthropogenic inputs of contaminant. (C) 2011 Elsevier Ltd. All rights reserved.

Radioactive emissions into the atmosphere from the damaged reactors of the Fukushima Dai-ichi nuclear power plant (NPP) started on March 12th, 2011. Among the various radionuclides released, iodine-131 ( 131I) and cesium isotopes ( 137Cs and 134Cs) were transported across the Pacific toward the North American continent and reached Europe despite dispersion and washout along the route of the contaminated air masses. In Europe, the first signs of the releases were detected 7 days later while the first peak of activity level was observed between March 28th and March 30th. Time variations over a 20-day period and spatial variations across more than 150 sampling locations in Europe made it possible to characterize the contaminated air masses. After the Chernobyl accident, only a few measurements of the gaseous 131I fraction were conducted compared to the number of measurements for the particulate fraction. Several studies had already pointed out the importance of the gaseous 131I and the large underestimation of the total 131I airborne activity level, and subsequent calculations of inhalation dose, if neglected. The measurements made across Europe following the releases from the Fukushima NPP reactors have provided a significant amount of new data on the ratio of the gaseous 131I fraction to total 131I, both on a spatial scale and its temporal variation. It can be pointed out that during the Fukushima event, the 134Cs to 137Cs ratio proved to be different from that observed after the Chernobyl accident. The data set provided in this paper is the most comprehensive survey of the main relevant airborne radionuclides from the Fukushima reactors, measured across Europe. A rough estimate of the total 131I inventory that has passed over Europe during this period was \textless1% of the released amount. According to the measurements, airborne activity levels remain of no concern for public health in Europe. © 2011 American Chemical Society.

A new certified reference material (CRM) for radionuclides in sea water from the Irish sea (IAEA-443) is described and the results of the certification process are presented. Ten radionuclides (3H, 40K, 90Sr, 137Cs, 234U, 235U, 238U, 238Pu, 239+240Pu and 241Am) have been certified, and information values on massic activities with 95% confidence intervals are given for four radionuclides (230Th, 232Th, 239Pu and 240Pu). Results for less frequently reported radionuclides (99Tc, 228Th, 237Np and 241Pu) are also reported. The CRM can be used for quality assurance/quality control of the analysis of radionuclides in water samples, for the development and validation of analytical methods and for training purposes. The material is available in 5 L units from IAEA ( http://nucleus.iaea.org/rpst/index.htm ). © 2011 Akadémiai Kiadó, Budapest, Hungary.

The aim of this work was to compare the distribution of 137Cs in organisms after chronic ingestion following different schedules. Rats were contaminated through drinking water containing 6,500 Bq L-1 of 137Cs, starting either at birth, at weaning, or upon reaching adult age (13 wk). Animals were then sacrificed after different durations of ingestion. 137Cs content of organs and excreta were determined by γ counting. A slight decrease in Cs elimination through urine was observed according to the age of animals. All organs tested showed similar 137Cs content, with the exception of striated muscles and the thyroid at certain ages, which showed the highest accumulation of Cs. The lowest 137Cs concentration was found in the blood, which acts as a transfer compartment after absorption in the intestine. Substructures of the central nervous system showed a homogeneous level of 137Cs accumulation, except for the olfactive bulbs. In these structures, an increased concentration of 137Cs was observed, suggesting a possible direct route of intake through the nasal epithelium. Overall, these results are in agreement with current models for the biokinetics of 137Cs. However, these results also suggest that the thyroid should be taken into account in future models of 137Cs biokinetics. Copyright © 2010 Health Physics Society.

The present study focuses on the exceptional Saharan dust event that affected most of France in February 2004. Activity levels of various artificial radionuclides (90Sr, 137Cs, uranium, thorium and plutonium isotopes, 241Am) were examined. Activity or isotopic ratios are discussed in the context of atmospheric nuclear weapons tests, among them French tests performed in Sahara in the 1960s. The daily evolution of 137Cs activity levels in the atmosphere was compared to daily PM10 change. A link between airborne 137Cs and PM10, is given. It is estimated that this 2-day event deposited as much 137Cs as would be deposited on average over a 10-month period. The amount of deposited 137Cs and 239+240Pu represents respectively about 0.1 and 1% of the activity already present in the soil. Such Saharan dust events correspond to an extreme type of " feeder" process of artificial radionuclides in the atmosphere. Therefore, they contribute to the long term background level of artificial radionuclides kept at trace levels in the atmosphere. © 2010 Elsevier Ltd.

International audience; We determined the sedimentation rates near a managed embankment on the Lower Rhone for the second half of the twentieth century. This was carried out using a combination of chronological indicators (137Cs, 241Am, dendrochronology and archived data) and sedimentological measurements. A high-resolution chronological sequence has emerged from these data sets. The average annual sedimentation rate of 14 cm has increased progressively over the last 50 years, and at a much faster rate than observed elsewhere on this river. This is probably due to a combination of factors such as the size of the river, abundance and coarse texture of the solid load, and local impact of river engineering works. We also studied hydrological and sedimentological characteristics for a number of flood events. © 2009 Elsevier B.V. All rights reserved.

The typical situations found in in situ gamma spectrometry have been simulated by Monte Carlo techniques to obtain the energy spectra of the photon fluence rate existing at 1 m above ground. The main difficulty found with the model is its slow convergence. A method to speed up the calculation has been derived. The results of the model have been thoroughly tested against existing data. In a final stage, the specific activity to H*(10) conversion coefficients have been derived for the typical scenarios encountered in the in situ gamma spectrometry. © The Author 2007. Published by Oxford University Press. All rights reserved.

In 1999 and 2002, the EURADOS Working Group on Environmental Monitoring organised two European intercomparison exercises of national network systems used to provide early warning in case of a nuclear accident. In total, 12 European countries, represented by more than 40 scientists, participated in these two intercomparisons with more than 35 different dose rate detectors. In addition, an in situ gamma spectrometry intercomparison was performed by a group of European scientists during the 2002 exercise. Results of these spectrometry measurements will be reported elsewhere. This report summarises the results of the second intercomparison, performed in 2002, at the environmental dosimetry facilities of the Physikalisch-Technische Bundesanstalt (PTB) in Germany. The unique combination of the ultra-low background Underground Laboratory (UDO) and two free-field sites (a floating platform on a lake showing an almost pure cosmic radiation field and a free-field gamma ray irradiation facility) provide the particular opportunity to precisely quantify the inherent background of the detectors and to calibrate them almost free of any background and traceable to PTB's primary standards. In addition, the intercomparison comprised investigations on the energy and dose rate dependence of the detectors' response to gamma radiation as well as on the response to cosmic radiation. Finally, the sensitivity of the detector systems to small dose rate variations, similar to that caused by a passing overhead radioactive plume, was studied under realistic free-field conditions. Following the Council Directive 96/29/EURATOM, the participants of the 2002 intercomparison were asked to report their results in terms of the operational quantity ambient dose equivalent, H*(10). Although the verification of the individual calibrations showed smaller discrepancies than those in the 1999 intercomparison, in a few cases, these discrepancies would be still unacceptably high in the case of a real emergency situation as demonstrated by the plume results. This shows the clear need for further efforts towards a European harmonisation in environmental dosimetry. For this purpose, a further intercomparison shall be held at the PTB in 2006, especially with the participation of new members of the European Union. © The Author 2006. Published by Oxford University Press. All rights reserved.

The IRSN (Institut de Radioprotection et de Surete Nucleaire, France) has started an in situ study of the behaviour of atmospheric releases close-by the COGEMA La Hague nuclear reprocessing plant. The study is designed to improve information on the dispersion of radioactive pollutants very close to the emission point—a 100 m height chimney. In this situation, close to the emission and height of the emission, Gaussian models generally used to predict the behaviour of atmospheric releases are not well adapted. The study is based on the characterisation of the 85 Kr emitted during normal operations of the reprocessing process. Temporal and spatial variations of the plume shape were investigated with intensive in situ measurements. Live in situ techniques to measure the electrons and the photons emitted by the 85 Kr have been implemented and will be described. Preliminary results showing the interest of the techniques were presented. Variations of the dose rates created by the photon flux of a plume were directly measured and correlated to other quantities.

Since the time coverage of BATSE is nearly complete over 8 years, this instrument offers a unique opportunity to monitor highly variable sources such as blazars in a relatively unexplored energy band (20–100 keV). Here we present some examples of this capability which is particularly useful during period of flaring activity. Four years of monitoring of the QSO 71.07 in the hard X-ray band is presented which indicates enhanced hard X-ray emission during an optical flare. BATSE also allowed the extraction of spectra during bright states. These data indicate that the spectrum steepens when the source is brighter. Results are also presented for the BL Lacs MKN501 and PKS 2005-489 during high energy flares, first detected by other instruments. The potential of using BATSE to study sources over long periods of time and to follow the emission before and after flares is clearly demonstrated.

The BATSE Earth Occultation data is being successfully used to study the temporal and spectral properties of an unbiased sample of Seyfert 2 galaxies in the 20-100 keV energy range over a period of 8 years. The sample used is the enlarged Maiolino and Reike sample restricted in distance to those (46) located within 42 Mpc from Earth. Of the 20 sources so far analyzed 12 were detected at greater than the 5 sigma level; some of these are new detections in the hard X-ray band. Preliminary results of this study are presented including example light-curves and spectra. To enlarge the scope of our study we also present a comparison of our data with data obtained by BeppoSAX. The implications of these results to the Unified Model of AGN, and the synthesis of the Cosmic Diffuse Background are discussed.

After 10357 h of running the NEMO-2 tracking detector with an isotopically enriched zirconium source (0.084 mol yr of 96Zr), a ββ2ν decay half-life of T1/2=(2.1+0.8(stat)−0.4(stat)±0.2(syst))·1019 y was measured. Limits with a 90% C.L. on the 96Zr half-lives of 1.0·1021 y for ββ0ν decay to the ground state, 3.9·1020 y to the 2+ excited state and 3.5·1020 y for ββ0νχ0 decay with a Majoron (χ0) were obtained. The data also provide direct limits at the 90% C.L. for the 94Zr half-lives. These limits are 1.1·1017 y for ββ2ν decay to the ground state, 1.9·1019 y for ββ0ν decay to the ground state and 2.3·1018 y for ββ0νχ0 decay to ground state.

The double beta decay of 106 Cd to the ground and excited states of 106 Pd is investigated both theoretically and experimentally. The quasiparticle random-phase approximation approach is used for the two-neutrino decay mode calculations. Estimations show that detections of β + EC decays to the ground state and 0 1 + excited state and ECEC(0 + a 0 1 + ) transition could be detected with today low-background techniques. Using a HPGe detector and an external source of natural cadmium, new stringent limits on β + β + (0 ν + 2 ν ), β + EC(0 ν + 2 ν ) and ECEC(0 ν + 2 ν ) decays into the ground and excited states are derived.

New limits on double beta processes in 92Mo have been obtained using a 400 cm3 HPGe detector and an external source of high-purity natural molybdenum. At confidence level CL= 90% they are 1.9 · 1020 y for the (0v + 2v)β+EC transition to the ground state, 8.9 · 1020 y and 8.1 · 1020 y for the (0v + 2v)ECEC transitions to first excited 2 1 + and 0 1 + states in 92Zr, correspondingly.

Spatial distributions and temporal changes of radioactive fallout released by the Fukushima Dai-ichi Nuclear Power Plant accident have been investigated by two campaigns with three measurement schedules. The inventories (activities per unit area) of the radionuclides deposited onto ground soil were measured using portable gamma-ray spectrometers at nearly 1000 locations (at most) per measurement campaign. Distribution maps of the inventories of (134)Cs, (137)Cs, and (110m)Ag as of March, September, and December 2012 were constructed. No apparent temporal change of the radionuclide inventories was observed from March to December 2012. Weathering effects (e.g., horizontal mobility) were not noticeable during this period. Spatial dependence in the ratios of (134)Cs/(137)Cs and (110m)Ag/(137)Cs were observed in the Tohoku and Kanto regions. The detailed maps of (134)Cs and (137)Cs as of September 2012 and December 2012 were constructed using the relationship between the air dose rate and the inventory.

The Pauli Exclusion Principle (PEP) was tested with the NEMO-2 detector. Limits at the 90% C.L. on the violation of PEP for p-shell nucleons in 12C were obtained. Specifically, transitions to the fully occupied 1s1/2-shell yielded a limit of 4.2 · 1024 y for the process with emission of a γ-quantum. Similarly limits of 3.1 · 1024 y for β− and 2.6 · 1024 y for β+ Pauli-forbidden transitions of 12C →12N12B) are reported here.

The NEMO-2 tracking detector located in the Frejus Underground Laboratory was designed as a prototype of the NEMO-3 detector to study neutrinoless (Oν) and two neutrino (2ν) double-beta decay (ββ) physics. After 10357 h of running with an isotopically enriched selenium source (2.17 mol yr of 82Se) a ββ2ν decay half-life of T 1 2 = (0.83 ± 0.10( stat ) ± 0.07 ( syst )) × 10 20 yr was measured. Limits with a 90% C.L. on the 82Se half-lives of 9.5 × 1021 yr for ββ0ν decay to the ground state, 2.8 × 1021 yr to the (2+) excited state and 2.4 × 1021 yr for ββ0νχ0 decay with a Majoron (χ0) were also obtained.