La responsabilité des références françaises pour la fluence et les grandeurs dosimétriques neutroniques est du ressort du laboratoire de métrologie et de dosimétrie des neutrons de l’Institut de radioprotection et de sûreté nucléaire (IRSN). C’est dans ce cadre, que l’institut développe et exploite, à Cadarache, des installations produisant des champs neutroniques de référence pour des utilisations diverses. Certaines (sources radioactives émettrice neutrons respectant la norme ISO 8529-1) sont utilisées pour effectuer des étalonnages de routine de dispositifs de mesure. D’autres installations produisent des champs neutroniques « réalistes » simulant les champs rencontrés sur les postes de travail en modérant les champs neutroniques générés à partir de sources radioactives ou d’accélérateurs. Enfin, l’installation AMANDE dont l’inauguration a eu lieu en mai 2005 produit des champs de neutrons monoénergétiques d’énergie comprise entre 2 keV et 20 MeV à partir de l’interaction de particules chargées accélérées jusqu’à 4 MeV sur différentes cibles. Avec l’arrivée de cette dernière installation, l’IRSN offre un plateau technique très complet pour la production de tous les types de champ neutronique recommandés par les normes internationales pour l’étalonnage des instruments de détection des neutrons.

Gamma-ray energy absorption buildup factors of gaseousmixtures; neon (95%) + argon (5%), argon (95%) + acetylene (5%),argon (95%) + methane (5%), argon (95%) + carbon dioxide (5%), methane(70%) + pentane (30%) and argon (90%) + methane (10%) were studiedby Geometrical Progression (G-P) fitting for the photon energy range0.015-15 MeV. It was found that the equivalent atomic number, Zeq ofthe gaseous mixtures sharply reduces after 1 MeV photon energy. TheZeq for the mixture of methane (70%) + pentane (30%)is the minimum, whereas the maximum is for argon (95%) + carbondioxide (5%) for the photon energies under investigation. The EnergyAbsorption Buildup Factor (EABF) for methane (70%) + pentane (30%)was found to be the highest among all the selected gaseous mixtures.The chemical composition of the gaseous mixtures has an impact onthe EABF values for photon energy and penetration depth. The investigationof the EABF is useful for selection of gaseous mixtures in designconsideration of gaseous radiation detectors for gamma radiation.

This work aimed at treating the new database on cesium-137 and strontium-90 transfer by wash-off collected by IRSN in the framework of the Franco-German Initiative for Chernobyl. It focused on the 71 runoff plot (from 1 to 400 m2) experiments conducted under artificial rainfalls in the Chernobyl district between 1986 and 1998. These data, mostly still unpublished, provide a quantification of wash-off at the rainfall scale, still rare for radionuclides. Normalized entrainment coefficients by liquid and solid wash-off were calculated for each experiment. In average, the liquid entrainment coefficient was 10-5 mm-1 for cesium, and 10-3.8 mm-1 for strontium. The solid entrainment coefficient was 10-41 m2g-1 for cesium and 10-4.3 m2g-1 for strontium. These trends and values were found consistent with reported values in the literature. For assessment purposes, the extrapolation of these coefficients to wider areas and to other sites would need their physical interpretation.

Public exposure to radioactive gas radon and its progeny present in the air results in the largest contribution to total effective dose received by human beings. It is therefore of great concern to monitor radon concentration in energy conserved air tight buildings. Measurements of radon in the Fatima Jinnah Women University (FJWU) have been carried out for investigation and comparison of radon concentration in the new and old buildings of the campus at Rawalpindi, Pakistan. The study was done because according to the international guidelines concerning environmental problems, it is necessary to evaluate and know the radon levels, especially since most of the natural radiation dose to human beings comes from radon gas and its progeny. Solid State Nuclear Track Detectors (SSNTDs) being efficient, therefore, the measurements were carried out by passive, time integrated method, using CR-39 detector in polythene bags. The detectors were exposed for more than six month in various loctations indoors and outdoors. The detectorswere etched using NaOH, the tracks were counted manually, and the track density was converted to radon concentration. Radon concentration varied from 31 to213 Bq.m–3 in old building and from 27 to 143 Bq.m–3 in new buildings, showing slight elevated values in the old buildings. Radon concentration values were found to be less than the values quoted by radiation protection agencies. Radiation dose due to radon varied in the university campus depending on occupancy factor.

The environmental abundances of 129I and 127I in Lower Saxony, Germany, and their pathways to animals and man were investigated. The iodine isotopes are in severe disequilibrium in the different environmental compartments. Today, the environmental isotope ratios range from 10-6 to 10-10. The highest ratios were found in North Sea water, the lowest in deep soil samples and ground water. A differentiation by about a factor of ten between the iodine isotopes was observed for different air-borne iodine species. Time series for iodine in precipitation show a decade-long increase of 129I fallout until the 1990ties and an ongoing constant input of 129I with deposition densities of ~ 15 mBq m-2 per year. In surface waters, a dilution of the fall-out iodine takes place by stable iodine which is just weakly adsorbed in the soils. The isotope ratios in soils and ground waters demonstrate a high mobility and an accumulation of 129I in the water unsaturated soil zones and an efficient migration into water saturated soil layers and ground water. The transfer into the food chain is ruled by the complex situation in the water-soil system. Given the environmental 129I abundances, the relatively low 129I/127I ratios in human thyroid glands (2 × 10-9 - 3 × 10-8) can only be explained by additional iodine sources with low ratios in the diet.

The study was done to determine concentrations of radionuclides and heavy metals and to evaluate the frequency of chromosomal aberrations in samples of Elodea canadensis, a submerged plant, collected in different parts of the Yenisei River. Samples were collected in the area subjected to radioactive impact of the Mining-and-Chemical Combine (MCC) at Zheleznogorsk and in the control areas, upstream of the MCC. The investigations showed that Elodea biomass in the area affected by MCC operation contained a long inventory of artificial radionuclides typical of the MCC discharges. Upstream of the MCC, in the control sampling areas, the sediments and the Elodea biomass contained only one artificial radionuclide – 137Cs. Thus, the exposure doses to Elodea shoots and roots upstream of the MCC are small (not more than 8 μGy/d) and the main contribution to them is made by natural radionuclides. At the MCC discharge site (the village of Atamanovo) and downstream of it, the total dose rate increases almost an order of magnitude, reaching its maximal values – 72 μGy/d for Elodea shoots and 58 μGy/d for roots. Cytogenetic investigations of Elodea roots showed that at the MCC discharge site (the village of Atamanovo) and downstream of it the occurrence of chromosomal aberrations in ana-telophase and metaphase cells of Elodea was considerably higher than in the control area. It is highly probable that this simultaneous dramatic increase in the total exposure rate and the occurrence of chromosomal aberrations in Elodea is associated with the radiation factor. It is suggested that Elodea is affected not only by the radiation factor but also by the chemical factor – toxicity of heavy metals.

De 1977 à 2009, plus de 600 analyses d’activités en tritium organique ont été réaliséessur les poissons, les végétaux aquatiques et les sédiments, en amont et en aval des 15CNPE français situés en bord de rivière. L’exploitation de ces résultats montre que lesactivités en tritium organique ont diminué de façon exponentielle au cours des trentedernières années, dans tous les compartiments des écosystèmes aquatiques. Dans les zonesen amont de tout CNPE, les activités en tritium organique dans les sédiments sontsupérieures aux activités mesurées dans les poissons et les végétaux, elles-mêmessupérieures aux activités en HTO des eaux de surface. L’ampleur de ces écarts dépend dubassin concerné et s’explique par la nature différente des sources de tritium. Dans lesbassins versants où les retombées des essais nucléaires atmosphériques constitue la sourceprincipale de tritium, les niveaux observés résultent de l’exposition des organismesaquatiques à deux formes distinctes de tritium d’âges différents : l’eau tritiée del’atmosphère, image des retombées au moment du prélèvement, et le tritium organique dessols, formé sur plusieurs dizaines d’années, qui alimente le compartiment sédimentaire descours d’eau. Dans les bassins du Rhône et du Rhin, une source supplémentaire de tritium detrès faible biodisponibilité, provenant vraisemblablement de l’industrie des peinturesluminescentes, marque la matière organique des sédiments à hauteur de 100 à 100 000Bq.L-1 d’eau de combustion. La comparaison des niveaux observés en amont eten aval des CNPE montre que l’influence des rejets est détectable seulement dans les coursd’eau où le bruit de fond est faible, c’est-à-dire dans les bassins autres que ceux duRhône et du Rhin. L’augmentation des activités en tritium organique dans les végétaux etles poissons est inférieure à l’augmentation de l’activité en HTO due aux rejets, ce quitémoigne, d’une part, de l’absence de phénomène de bioaccumulation à partir de l’eautritiée et, d’autre part, de l’absence de composés organiques bioaccumulables dans lesrejets.

A workshop dedicated to cancer risks associated withlow-dose internal contamination was organised in March 2011, inParis, in the framework of the DoReMi (Low Dose Research towardsMultidisciplinary Integration) European Network of Excellence. Theaim was to identify the best epidemiological studies that providean opportunity to develop a multidisciplinary approach to improvethe evaluation of the cancer risk associated with internal contamination.This workshop provided an opportunity for in-depth discussions betweenresearchers working in different fields including (but not limitedto) epidemiology, dosimetry, biology and toxicology. Discussionsconfirmed the importance of research on the health effects of internalcontamination. Several existing epidemiological studies providea real possibility to improve the quantification of cancer riskassociated with internal emitters. Areas for future multidisciplinary collaborationswere identified, that should allow feasibility studies to be carriedout in the near future. The goal of this paper is to present anoverview of the presentations and discussions that took place duringthis workshop.

L’association et la collaboration étroite de plusieurs disciplines (physique des rayonnements, biomécanique, radiologie et orthopédie de l’enfant) a permis la mise au point dans notre pays et le développement d’un nouvel appareil d’imagerie dénommé EOS dont les principales caractéristiques sont : (1) la réduction considérable des doses de rayons X (de 8 à 10 fois moins pour la radiologie bidimensionnelle, de 800 à 1000 fois moins pour la tomodensitométrie tridimensionnelle) grâce au détecteur gazeux inventé par Georges Charpak qui lui ont valu le prix Nobel. (2) L’étude du patient en position debout obtenant des clichés simultanés de face et de profil du sommet de la tête jusqu’à la plante des pieds.(3) La possibilité de reconstruction 3D de tous les niveaux ostéo-articulaires a été vérifiée aussi précise que celle obtenue par tomodensitométrie conventionnelle. De plus, l’examen est effectué en position fonctionnelle debout ou assise, ce qui n’était pas possible avec les appareils de tomodensitométrie actuellement tous en position couchée. La reconstruction 3D peut être obtenue dans des délais acceptables de 15 à 30 minutes pour un rachis complet. Ne faisant pas double emploi avec l’IRM, même si celle-ci évolue aussi vers la position debout, EOS permettra des études de la pathologie ostéo-articulaire jusque-là jamais réalisées (en particulier du rachis et des membres inférieurs) avec un examen d’ensemble de l’individu au lieu des segments fragmentés donnés jusqu’à présent par les moyens actuels, radiographies conventionnelles ou tomodensitométrie.

In the UK, research funded by the Environment Agency/English Nature has provided a series of spreadsheet-based assessment tools for calculating doses received by biota in coastal, freshwater and terrestrial ecosystems. The approach uses the reference organism concept where the organism of interest (feature species) is equated to a particular reference organism (based on its physical geometry and ecology). This paper describes the stages followed to collate additional species-, and site-, specific data and to undertake assessments to determine whether Natura 2000 sites are adequately protected from authorised releases of ionising radiation. The feature species used for the assessment were species listed under the EC Birds and Habitats Directives. The paper will describe the overall assessment process followed by the UK Environment Agency, demonstrating the staged assessment process adopted; how each feature species is mathematically aligned with the most appropriate reference organism geometry; and provide an example of the assessment conducted for the Natura 2000 sites located in the Humber Estuary, UK.

Indoor radon measurements were carried out in 30 elementary schools in Tunis, the capitalcity of Tunisia, during the winter months of December 2008 to early March 2009. Twoclassrooms, one each from ground floor and first floor were chosen from each school makinga total of 60 classrooms. In some of the classrooms, two detectors (open and closed) wereused to measure the concentrations of radon as well as radon and its progeny to allow thecalculations of the equilibrium factors. Nuclear track detectors type LR-115 (Kodalpha)were used for the measurements. The results show that the radon concentration levels arelow in the range of 6–169 Bq m-3 with a mean value of 26.9 Bq m-3.The annual effective dose was found to vary between 0.025–0.715 mSv y-1 forteachers while the range for pupils was from 0.019–0.525 mSv y-1. These valuesare within the ICPR recommended values.

Les codes de calculs Monte Carlo, précis mais lents, sont devenus des outils incontournables dans la grande majorité des spécialités liées à la radiophysique, la radioprotection et la dosimétrie. Une réflexion mérite d’être menée sur l’opportunité d’implémenter d’autres solutions informatiques qui ne seraient pas seulement basées sur l’unique puissance informatique ou sur un « biaisage » permettant une relative accélération de ces calculs dans les cas des rayonnements photoniques, mais sur des méthodes plus judicieuses (RNA-réseaux de neurones artificiels, RàPC — raisonnement à partir de cas ou exploitation d’autres techniques informatiques), déjà utilisées avec succès depuis longtemps dans certaines applications scientifiques ou industrielles dans les domaines souvent éloignés de la radioprotection ou de la dosimétrie médicale.

The main purpose of the study is establishment how radioactive contamination with different exposures affect aquatic living organisms by means of the fluctuating asymmetry determination. Studies are also aimed for the assessment of relative contamination of the water bodies by man-made radionuclides taking into account biological aspects. Represented results of studies are the pilot researches towards to the estimation of bilateral asymmetry of aquatic organisms in conditions of long-term radioactive impact and can be the part of complex radioecological monitoring of aquatic ecosystems within the Chernobyl accident Exclusion Zone in future.

Some crops of important nutritive requirements have been collected from farmlands located in Bitsichi an old tin mining town in north central region of Nigeria. The food crops were analyzed in order to determine trace element concentrations level using Neutron Activation Analysis (NAA). The activity concentrations due to natural radionuclides in the food samples and soil samples collected within the root zone of the crops were also determined using gamma-ray spectrometry (GRS). The NAA results obtained showed higher concentration of Potassium among the essential elements in all the crops. Calcium concentration in both maize and Guinea corn was below detection limit and also Zn in Green beans, sweet potato and cassava. The trace elements; Sc, Hf, Sm, and Th, were below detection limit in all the crops except in Green beans. Rubidium (Rb) and lanthanum (La) were below detection limits only in Cabbage. The activity concentrations of the natural radionuclides in the food samples were found to vary between 83 and 129 Bq kg-1 for 40K, 19 and 30 Bq kg-1 for 226Ra and 27 to 41 Bq kg-1 for 232Th. In the soil samples the activity concentrations varied between 177 and 271 Bq kg-1 for 40K, 53 and 96 Bq kg-1 for 226Ra and 73 to 176 Bq kg-1 for 232Th. Results of activity concentration levels of the radionuclides obtained in similar crops collected for control measurements were found to be very low compared to those from the study area. The effective dose due to intake of the food crops considered in the study area was estimated based on the measured activity concentrations of 226Ra and 232Th in the food crops. It was found to vary between 0.01 mSv y-1 (Acha) and 1.35 mSv y-1 (Cassava) with a cumulative total dose estimated as 2.5 mSv y-1. The mining activities in the area are seen to have influenced the concentration of these trace elements and radionuclides in the food crops. However, they are seen not to pose any serious internal health burden due to ingestion given the realities of food choice by individuals in the study area.

This study estimates in terms of amount and localisation the pulmonary retention of dissociated Pu/Am in the rat for the first week following an inhalation exposure to industrial PuO2 aerosols by combining standard biokinetic methods, quantitative analysis of contact autoradiograph obtained from lung section, and treatments by DTPA performed either in vivo or in vitro. The dissociated actinides mainly involved dissolved forms which are homogeneously distributed within lung parenchyma. Most of these chemical forms appears to come from the fraction (fr) of radioelements which seems to dissolve before particles phagocytosis mainly by alveolar macrophages. Early pulmonary administration of dry diethylenetriaminepentaacetic acid (DTPA) powder (+2 hours) decorporates ~90% of these actinide forms, whereas, a delayed treatment (+1 week) is far less efficient. By contrast, a similar extraction (~90%) of the dissolved actinides from lung sections of rat untreated by the chelating agent is measured after their incubation in a DTPA solution for both 2 hours and 7 days post-exposure times. These results can be explained by a gradual internalisation of a fraction of the early dissolved actinides (mainly Am) in alveolar cells, but not preferentially in alveolar macrophages, whereas the remaining fraction of dissolved actinides are transferred to blood. From these observations, a new model is proposed to help for interpretation of human bioassay data obtained after internal contamination and DTPA treatments.

L’utilisation médicale des rayonnements ionisants estdevenue la source d’irradiation la plus importante à l’échelle mondiale.Les connaissances et aptitudes des professionnels utilisateurs deces rayonnements déterminent la mise en œuvre des mesures de radioprotectionrecommandées par les organismes internationaux et nationaux. Lasituation de la radioprotection dans les pays africains est préoccupanteen raison de la faiblesse des lois, règlements et organismes de radioprotection.Nous rapportons les résultats d’une enquête effectuée dans des serviceshospitaliers détenteurs de sources de rayonnements ionisants à Yaoundé,capitale du Cameroun. Plus de la moitié des professionnels enquêtés ontun niveau moyen de connaissances des principes et normes de radioprotectionet plus de 80 % n’ont jamais bénéficié d’une formation continueen matière de radioprotection.

The basis premise of many radiological assessments is the assumption that the transfer of many radionuclides from soil to herbage and hence animal derived food products is a positive linear relationship for a given set of ecological conditions. However, a number of authors have published results, which they conclude demonstrate non-linear transfer of radiocaesium to plants and animals with transfer being highest when soil concentrations are lowest. Whilst we may expect non-linear transfer of radionuclides under homeostatic control or present in comparatively large chemical quantities, there appears no credible hypothesis to support such an observation for radiocaesium. In this paper we review those articles, which have reported non-linear radiocaesium transfer and also analyse novel data. We argue that saturation of Cs uptake as suggested by some other authors is unlikely. Sampling bias, statistical data distribution and countermeasure application are suggested as potential contributors. However, we have not been able to provide a conclusive reason for such observations. Given the important implications for foodchain modelling further consideration of available data is required to more comprehensively answer this question

À la suite d’un accident radiologique dû à une source de gammagraphie survenu au Chili en décembre 2005 et impliquant une victime, l’IRSN a été sollicité pour réaliser la reconstitution dosimétrique par calcul Monte Carlo. Des outils, développés au laboratoire, associant des fantômes anthropomorphes mathématiques et voxélisés au code de calcul Monte Carlo mcnpx ont été mis en œuvreafin de déterminer la distribution de dose au niveau de la fesse gauche de la victime et la dose aux organes critiques. La cartographie dosimétrique réalisée au niveau de la fesse gauche montre que la dose à la surface est importante (1900 Gy) et chute rapidement pour atteindre 20 Gy à 5 cm de profondeur. Les calculs réalisés avec un fantôme mathématique indiquent que les doses moyennes aux organes critiques sont faibles et permettent d’identifier de possibles sites de prélèvement de moelle osseuse. S’appuyant sur la cartographie dosimétrique, une exérèse de 5 cm de profondeur et de 10 cm de diamètre a été pratiquée au niveau de la fesse gauche de la victime.

The need to increase the predictive power of risk assessment for large tritium releases implies a process level aproach for model development. Tritium transfer for atmosphere to plant and the conversion in organically bound tritium depend strongly on plant characteristics, season, and meteorological conditions. In order to cope with this large variability and to avoid also, expensive calibration experiments, we developped a model using knowledge of plant physiology, agrometeorology, soil sciences, hydrology, and climatology. The transfer of tritiated water to plant is modelled with resistance approach including sparce canopy. The canopy resistance is modelled using Jarvis-Calvet approach modified in order to directly use the canopy photosynthesis rate. The crop growth model WOFOST is used for photosynthesis rate both for canopy resistence and formation of organically bound tritium, also. Using this formalism, the tritium transfer parameters are directely linked to known processes and parameters from agricultural sciences. The model predictions for tritium in wheat are closed to a factor two to experimental data without any calibration. The model also is tested for rice and soybean and can be applied for various plants and environmental conditions. For sparce canopy the model uses coupled equations between soil and plants.