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The paper elaborates on the international safety standards related to demonstrating the safety of radioactive waste disposal and provides on overview of the intercomparaison and harmonization projects presently underway.

In order to assess the level of residual radioactivity and evaluate the radiological conditions at the former French nuclear testing sites of Reggane and Taourirt Tan Afella in the south of Algeria, the International Atomic Energy Agency, at the request of the government of Algeria, conducted a field mission to the sites in 1999. At these locations, France conducted a number of nuclear tests in the early 1960s. At the ground zero locality of the ‘‘Gerboise Blanche’’ atmospheric test (Reggane) and in the vicinity of a tunnel where radioactive lava was ejected during a poorly contained explosion (Taourirt Tan Afella), non-negligible levels of radioactive material could still be measured. Using the information collected and using realistic potential exposure scenarios, radiation doses to potential occupants and visitors to the sites were estimated.

As part of its functions, the IAEA periodically reviews the status and continued relevance of the safety standards to the needs of its Member States. Recent work is described on the development of standards for the radioactive discharge control including the development of practical guidance for setting discharge limits, the elaboration of a methodology for the radiation protection of non-human species, and the preparation of guidance on environmental modeling and monitoring for radiation protection purposes. The development of the IAEA safety documents is influenced both by the new ICRP recommendations and feedback from practical experience of application of existing standards. Recent international and regional tendencies, to reduce radioactive discharges below levels justified by radiological criteria are discussed.

(Manuscrit i-qu le 1 i fei’rirr 2003, occ.epi‘: Ir 19 .septembre 2003) 17 ans apres l’accident de Tchernobyl, cette etude propose une reconstitution des depots de 137Cs dus a cet accident sur l’ensemble du territoire fran ais metropolitain. Cette reconstitution est basee sur la relation entre les depots de ‘”CS et les pluies de la premiere semaine de mai 1986, validee sur le tiers-est du pays, et sur une modelisation de l’appauvrissement d’est en ouest des masses d’air contaminees. La carte proposee, etablie suivant la meme methode geostatistique que celle utilisee par la Commission europeenne, est coherente avec les estimations des depots de ‘37Cs dans les pays d’Europe voisins. I3’Cs deposition mapping in May 1986 over the whole French metropolitan territory. This study intends to reconstruct the I3’Cs deposition over the French territory resulting from the Chernohyl accident, 17 years after its occurrence. This reconstruction b based on the caesium fallout versus atmospheric precipitation relationship during the first week of May 1986, already determined for the Eastern France and the modelling of air masses radioactive load decreaie toward West. The deposition map is ohtained following the methodology used for the European Commission Atlas. Our map is consistent with estimated deposit over neighhouring countries.

Dix sept ans apres l'accident de Tchernobyl, toutes les donnees de mesure de la radioactivite dans l'environnement faites a l'epoque par les differents services de l'Etat ont ete collationnees et validees. Ces donnees etaient appropriees pour evaluer dans des delais satisfaisants, les consequences des retombees de cet accident pour la grande majorite de la population francaise. En revanche, elles ne permettaient pas, du fait de l'absence de prise en compte de l'importance des precipitations, d'evaluer la contamination des produits alimentaires locaux dans les regions de l'Est de la France ou les depots ont ete tres superieurs aux moyennes. Ainsi, la capacite de mesure mobilisee a la suite de cet accident n'a pu etre focalisee sur des productions sensibles telles que les laits de brebis et de chevre en Corse dont la consommation a pu conduire a des doses a la thyroide des enfants significativement superieures aux moyennes estimees pour l'Est de la France. Aujourd'hui, l'experience de l'IRSN permettrait de mieux optimiser l'utilisation des moyens de mesures et de mieux assimiler les donnees produites. Toutefois cette optimisation ne pourra etre complete sans que soit conduite l'analyse prealable de la sensibilite radioecologique des differentes composantes geographiques du territoire francais qui doit guider toute strategie d'echantillonnage.

The natural nuclear fission reactor at Bangombe is located at a depth of approximately 12 m and has undergone supergene weathering and chemical exchange with groundwater under moderately oxidizing conditions. This reactor has been studied as an analogue for the migration of radionuclides in a geologic repository. Five water samples were taken from a drill hole in the reactor zone and from drill holes that are situated along the direction of the groundwater flow. Dissolution of phosphates in the weathering profile provided an important mechanism for the mobilization of phosphorous and REE. This phosphorous allowed the formation of secondary minerals, e.g., phosphatian coffinites and Fe-uranyl phosphate hydroxide hydrates. The filtered groundwaters (dissolved phase) obtained directly from the reactor zone had anomalous 143Nd/146Nd, 145Nd/146Nd and 149Sm/147Sm isotope ratios of 0.7235, 0.4933 and 0.843, respectively, confirming mixing between a fissiogenic and normal REE component. In this dissoved phase, a small fraction of the Nd (2.3 at.%) is of fissiogenic origin. The suspended loads (filtered particulates) of the same groundwater from within the reactor show similar isotopic anomalies with a fissiogenic Nd contribution of 3.2 at.%. Similar fissiogenic Nd contributions are observable for groundwater samples from outside the reactor zone (3 m distance). Both dissolved and suspended load samples from the more distant well (25 m) have normal isotopic ratios. Thus, the prevailing physico-chemical conditions within this groundwater system allow the migration of the fissiogenic REE over at least 3 m but less than 25 m. Although REE phases are abundant in the reactor zone, the REE concentrations of the water in contact with the sediments of this zone are very low (

Avec des depots de 137 Cs depassant quelquefois 20 000 Bq m-2 , certains coteaux de la vallee du Rhone ont ete assez fortement touches par les retombees de l'accident de Tchernobyl. C'est le cas a Cornas (Ardeche) pres de Valence et a Vinsobres (Vaucluse) au nord de Vaison-la-Romaine. La vigne occupe dans ces regions l'essentiel des surfaces agricoles, pour la production d'un vin repute. Cette etude montre que les consequences des retombees de l'accident de Tchernobyl pour les vins de la vallee du Rhone ont ete visibles mais tres faibles. L'activite en 137 Cs du vin produit en 1986 n'a pas atteint 1 Bq/l. Ces consequences tres limitees sont dues a la date des depots qui sont intervenus debut mai 1986, alors que les vignes developpaient a peine leurs premieres feuilles. Depuis 1986, l'activite en 137 Cs du vin a fortement decru jusqu'a revenir en 2000 a un niveau proche de celle d'avant l'accident : quelques millibecquerels par litre. Le cesium ajoute aux sols, dans des proportions pourtant importantes, se trouve essentiellement dans les 20 premiers centimetres et est peu disponible pour les racines de la vigne.

Quelles sont les valeurs qui caracterisent sur le territoire francais les rayonnements ionisants et les radionucleides d'origine naturelle ? Comment distinguer dans le resultat d'une mesure la part qui resulte eventuellement d'une activite humaine ? Afin d'essayer de repondre a ces questions, un questionnaire a ete adresse aux differents organismes qui effectuent en France des mesures de radioactivite dans l'environnement. Les informations mentionnees dans cette etude se rapportent exclusivement a des observations faites dans l'environnement a l'exterieur des bâtiments et du perimetre des installations nucleaires de base (INB). En outre, elles ne concernent, sauf cas particuliers signales, que des mesures de rayonnements ou de radioelements d'origine naturelle dont les resultats n'ont pas ete perturbes par l'action de l'homme. L'enquete montre la difficulte actuelle de dresser en France un bilan exhaustif des connaissances acquises concernant les caracteristiques du bruit de fond radioactif d'origine naturelle dans l'environnement. Aujourd'hui en France, dans le domaine de la radioactivite naturelle, les efforts consentis manquent de coordination et d'orientation vers certaines priorites. A ce titre, les mesures des 238 U et 232 Th precurseurs des 226 Ra et 228 Ra, des descendants solides emetteurs alpha du radon (par la mesure des EAP du 222 Rn et 220 Rn), des emetteurs gamma post emanation (214 Pb, 214 Bi, 212 Pb), du 210 Pb, 210 Po et du 14 C doivent etre privilegiees.

The Nord-Cotentin radioecological study was conducted in different stages. First, an assessment tool was developed and implemented to estimate the number of leukaemia radio-induced by the operation of nuclear facilities of the La Hague site (Nord-Cotentin region, France). Then, an uncertainty analysis was initiated to verify if the confidence intervals around the best estimate previously calculated allows to confirm the low impact of the nuclear facilities. The modelling of the terrestrial ecosystems was especially studied because of the paucity of results of measurements. That is also why the methodology built to reconstruct the statistical laws for each parameter of the model mixes the bibliographic knowledge and exploitation of a national database of environmental measurements. The application of this methodology for up to forty parameters shows that the possibility of fitting an accurate distribution such as a normal or a lognormal law is strongly linked with the availability and the number of measured data.

In conjunction with an extensive radiocarbon program, ANTARES has also carried out AMS measurement of the radioisotopes 26 Al and 36 Cl with the recent addition of 129 I. Development of an AMS measurement capability for 10 Be and for the actinides is underway. These projects pose a range of technical challenges both in spectrometer performance and in sample preparation. This paper discusses the special aspects of the facility that have been developed to meet these needs, with emphasis on 36 Cl, 129 I and plans for future actinide measurements.

The vacuum distillation method of extracting soil water for stable isotope analysis was tested for three different types of soil characterized by high water content: (1) pure sand, (2) cambisol with high organic matter content, developed on calcareous sandstone under temperate climatic conditions (Austria), and (3) tropical latosol poor in organic matter, developed on sandy clay sediment (Brazil). The method yields accurate and reproducible results for sand, provided that more than 98% of the original soil water is extracted. The time required for complete extraction is a function of sample size and the applied extraction temperature. Column experiments with the clayey soils revealed existence of a weakly bound, easily exchangeable pool of water which is isotopically different from the mobile water. The experiments showed that the extracted soil water is depleted in both deuterium and oxygen-18 by 5–10% and 0.3–0.5%, respectively, when compared with the percolate (mobile water). This depletion depends strongly on the soil type. The reproducibility for replicate extractions of soil water from clayey soils is around ±3% and 0.3% for δD and δ 18 O, respectively.

The Rhône watershed extends over almost one hundred thousands square kilometers, i.e. one fifth of the metropolitan French territory. The Rhône is the major River entering the Western Mediterranean Sea as it generates the main source of sediments and freshwater (50%) to the sea, with an average water discharge of 1700 m3 s-1. The River input affects primary production significantly in the north-western Mediterranean area and plays a leading role on the marine ecosystem functioning in the whole Gulf of Lion. Almost twenty nuclear reactors are situated along the Rhône valley, representing Europe's biggest concentration of nuclear power plants. Down flow all these installations the spent fuel reprocessing plant of Marcoule released over many years most of the liquid radioactive wastes including plutonium isotopes in the Rhône river. Artificial radionuclides also originate from the weathering of the catchment basin labeled by both the global and the Chernobyl accident atmospheric fallout. These radioactive inputs have led to a permanent contamination of the Rhône river waters. Long-term chronological series of artificial radionuclide activities within the waters at the lower reaches of the Rhône river were acquired from 1979 to 2002. These data give evidence for various radioecological responses of the aquatic system over years. Based on these observations several major radioecological sensitivity factors for river waters are identified. © 2005 EDP Sciences.

The carbon isotopic composition of the total dissolved inorganic carbon in groundwater associated with a granitic pluton at Stripa (Sweden) reflects both inorganic and organic carbon sources. Following the uptake of soil carbon-dioxide, calcite dissolution dominates the geochemical evolution of shallow groundwater. Calcite saturation is reached at a depth of about 100 m. In deeper waters geochemical release of Ca and increasing pH cause calcite precipitation. Radiocarbon contents suggest carbon (and water ?) ages in excess of 20 000 years for waters at 300–400 m depth. In deep groundwaters with enhanced salinities organic carbon is added to the dissolved inorganic carbon either through bacterial activity (e.g, sulphate reducing bacteria) or the oxidation of organic compounds such as methane. The lowest radiocarbon contents were measured at the 300–400 meter levels and not in the deepest fluids. The distribution of 13C in the deep groundwaters suggests the existence of well-defined flowsystems with limited active hydraulic interaction. Isotope analyses on fracture calcites substantiate the complex geochemical history of the pluton.