1963-2013: 1963-2013 : Fifty years of anthropogenic tritium in our environment - Focus on the Rhône valley (south east France)

International audienc

Origins and trend of radionuclides within the lower Rhône River over the last decades

Geological and climatic diversity leads to significant spatial variability of naturally occurring radioactivity levels, whether in soils, sediments or natural waters. The activity level of Rhône sediments is estimated at 1450 Bq/kg, between the levels observed in the Loire (1925 Bq/kg) and Seine (730 Bq/kg). The largest amounts of radioactive effluent from nuclear facilities concern tritium, for which activity levels are currently 1000 times higher than the sum of artificial gamma emitters discharged. The proportions of naturally occurring 14C and 3H in the lower reaches of the River Rhône are estimated at 50 to 70% and <5%, respectively, with the remaining amount coming from nuclear facilities. Long-term records from River Rhône monitoring show that the level of radioactive contamination from artificial sources declined sharply starting in the early 90s, with the level divided by 10 to 100 depending on the element. Radioactivity of natural origin remained unchanged as expected

1963-2013: 1963-2013 : Fifty years of anthropogenic tritium in our environment - Focus on the Rhône valley (south east France)

International audienc

Développement d'un piégeur passif pour la surveillance du tritium atmosphérique

Le développement d'un dispositif passif de prélèvement du tritium atmosphérique a été initié en 2012 pour optimiser les moyens de surveillance régulière de l'environnement en complémentarité avec les dispositifs existants (barboteur, condenseur). Le concept devait répondre à des contraintes de simplicité de mise en œuvre sur le terrain (pas d'apport en énergie, compacité…) et présenter des performances équivalentes aux meilleurs dispositifs disponibles actuellement sur le marché. L'étude a porté sur le piégeage du tritium sous forme de vapeur d'eau dans l'air (HTO). Elle a intégré le design du piège de terrain, la sélection des matériaux utilisés, le développement d'une chambre à atmosphère contrôlée et d'un système de désorption des pièges passifs pour des analyses en laboratoire. Une série de tests de qualifications dans des conditions de laboratoire puis dans l'environnement a été menée. Les résultats obtenus avec ces prélèvements passifs démontrent une très bonne concordance avec ceux obtenus avec les moyens utilisés habituellement en routine (barboteurs, condenseurs) sur une plage d'activité couvrant le bruit de fond naturel jusqu'à des niveaux identiques à ceux des rejets gazeux des installations nucléaires. Ils démontrent en outre le potentiel offert par ce nouveau dispositif pour une utilisation opérationnelle en surveillance des rejets, de l'environnement mais aussi pour des études spécifiques de type cartographique ou une utilisation en situation de crise

Radiological quality Assessment of the Rhône River filtered waters at its lower course in the framework of water production for human consumption with historical and regional perspectives

International audienceThe public health code, including the Ministerial Decree of 11 June 2007, set four indicators to evaluate the radiological quality of drinking waters (&alpha; gross activity, &beta; gross activity, tritium activity and total indicative dose), as well as guide values and quality references. All of the data from the monitoring show that while the radioactivity of the natural origin course remained constant over time, the levels of radioactive contamination of the Rh&ocirc;ne from artificial sources declined sharply from the early 90s, i.e. 10 to 100 times following radionuclides. The data also emphasise that no threshold activities for &alpha; global, &beta; global and tritium was exceeded in filtered water of the Rh&ocirc;ne. The total indicative dose (TID) remained below 100 &mu;Sv/year. TID quantification from water samplings in 2011 in the downstream part of the Rh&ocirc;ne River (BRL channel), Orb river and H&eacute;rault river are all far below the quality references. The contribution to the TID of artificial radionuclides detected in these water systems was shown to be negligible (&lt;0.01%)

Radiological quality Assessment of the Rhône River filtered waters at its lower course in the framework of water production for human consumption with historical and regional perspectives

International audienceThe public health code, including the Ministerial Decree of 11 June 2007, set four indicators to evaluate the radiological quality of drinking waters (&alpha; gross activity, &beta; gross activity, tritium activity and total indicative dose), as well as guide values and quality references. All of the data from the monitoring show that while the radioactivity of the natural origin course remained constant over time, the levels of radioactive contamination of the Rh&ocirc;ne from artificial sources declined sharply from the early 90s, i.e. 10 to 100 times following radionuclides. The data also emphasise that no threshold activities for &alpha; global, &beta; global and tritium was exceeded in filtered water of the Rh&ocirc;ne. The total indicative dose (TID) remained below 100 &mu;Sv/year. TID quantification from water samplings in 2011 in the downstream part of the Rh&ocirc;ne River (BRL channel), Orb river and H&eacute;rault river are all far below the quality references. The contribution to the TID of artificial radionuclides detected in these water systems was shown to be negligible (&lt;0.01%).</p

Isotopic evidence of natural uranium and spent fuel uranium releases into the environment

Uranium and plutonium isotopes were measured in soils, sediments and waters in an area subject to the past and present discharges from the uranium conversion plant of Malvési (France). The isotopes 236U and 239Pu are well known activation products of uranium and they prove to be powerful tracers of spent fuel releases in soils and sediments. On the other hand 234U and 238U activities measured in waters can be used to distinguish between releases and background uranium sources. Such findings contribute to improve the monitoring of the actinides releases by nuclear fuel facilities (mining sites, conversion, enrichment and fuel plants, reprocessing plants). © The Royal Society of Chemistry 2011

Radionuclides in waters and suspended sediments in the Rhone River (France) - Current contents, anthropic pressures and trajectories

International audienceThe Rhone River is one of the most nuclearized river in the world. Radionuclide concentrations in water and 6 suspended sediments transferred to the marine environment were intensively monitored in this river over the last 7 decades (2002–2018). While more than 60% of plutonium, americium, cesium, cobalt, silver, beryllium and 8 actinium radioisotopes are carried by sedimentary particles, sodium, tritium, antimony and strontium are mainly 9 exported as dissolved species (>90%) due to their low affinity with particles. Most natural radionuclides contents 10 show low seasonal variation. No significant trends are observed over the last two decades for these elements, 11 even for 40K widely used in fertilizers after the middle of the last century, indicating that the basin has currently 12 converged towards geochemical equilibrium for all of them. In contrast, the concentrations of numerous 13 anthropogenic radionuclides originating from nuclear industries significantly declined since the beginning of the 14 2000s. Assuming no change of the current anthropic and climatic pressures over the next decades, apparent 15 periods, i.e. the time required for a reduction by half the concentrations in the downstream part of the Rhône 16 River, would be close to 6 years for most artificial radionuclides, except for tritium and other artificial radionuclides 17 conveyed to the river by soil leaching and erosion (90Sr, 241Am, plutonium isotopes) which would be far longer. 18 Referring to regional referential backgrounds, only few anthropogenic radionuclides specifically produced by 19 nuclear industries are still detectable at the downstream part of the Rhone River and excess contents of tritium, 20 238Pu and 241Am are observed in filtered waters

Caractéristiques radiologiques des canaux de transport d’eau – Exemple du réseau hydraulique régional Languedoc Roussillon

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