Dans une centrale nucléaire (CNPE), la localisation des points chauds est une préoccupation importante, car ils participent à la dose que reçoivent les intervenants, en particulier lors des opérations de maintenance. Depuis 2010, EDF et le CEA ont entrepris d’adapter une nouvelle génération de caméra gamma, GAMPIX, pour disposer d’un instrument portable dédié à cet usage. Ce système permet de superposer une image gamma à une image visible, afin de localiser les sources radioactives présentes dans un environnement. Des essais sur site au CNPE de Tricastin ont été associés aux développements spécifiques réalisés par le CEA, afin d’appréhender les conditions particulières rencontrées en CNPE, à la fois environnementales et radiologiques : l’énergie relativement élevée des gamma du cobalt 60 (1,17 et 1,33 MeV) et la présence d’un bruit de fond ambiant permanent. Cet article présente les principaux axes du cahier des charges initial, les développements réalisés pour y répondre, et les résultats obtenus lors des campagnes d’essais. Même s’ils étaient uniquement dédiés à la qualification de la caméra gamma, les tests réalisés ont montré des résultats très prometteurs, par exemple la mise en évidence de lignes de fuite le long d’une protection biologique ou le mouvement d’un point chaud dans une tuyauterie (par rapport à sa position identifiée). En dernier lieu, les développements futurs sont évoqués.

During and after the Fukushima accident, the IRSN collected and interpreted the results of radiological measurements performed on foodstuffs of terrestrial origin published by Japan's Ministry of Health between mid-March 2011 and July 2012. Analysis of the findings shows that the accident's date, livestock-rearing practices and the deposits' characteristics had a decisive influence. The fact that radioactive fallout occurred very early in the growing and breeding season largely explains the moderate contamination of most foodstuffs of terrestrial origin, notably in the areas with the largest deposits. In the case of dairy products and meat, feeding imported fodder to livestock in stables, a common practice in Japan, compounded the calendar effect. Measurements published in Japan have also borne out the particular sensitivity of mushrooms, including cultivated species, and game.

The gamma-ray exposure build-up factors of raw materials of bricks (soils and fly-ashes) in the state of Punjab were investigated for the photon energy range 0.015 to 15 MeV up to 40 mfp penetration depth by the geometrical progression (GP) method. Appreciable variations in the exposure build-up factor (EBF) are noted for the raw materials. The EBFs of the raw materials of bricks change depending on the photon energy, penetration depth and chemical composition. The build-up factors are low at low and high photon energies, whereas they are very high in the medium-energy region. The peak energy of the EBF for soils is 0.3 MeV and 0.2 MeV for fly ashes. The EBFs of the raw materials of bricks are also compared with those of bricks of red mud and common brick materials. Common bricks were found to have the lowest gamma-ray EBF. This study should be useful for emergency preparedness planning and emergency dose estimation for future planned nuclear power plants in the state of Punjab.

In this paper, the effect of additional adipose and muscle layers was investigated on the effective dose and the organ absorbed dose. Calculations were performed using the Monte Carlo N-Particle Transport Code (MCNP) and the ORNL mathematical phantom for external photon and neutron beams. Variations in adipose and muscle tissue thickness were modeled by adding layers of adipose and soft tissues around the torso of the phantom. The effective dose decreased by about 7%–40% when the thickness of the extra layer increased from 0.5 to 5 cm considering all photon energies (10 keV–10 MeV) and neutron energies (10–9–20 MeV) for anterior-posterior, posterior-anterior, left-lateral, right-lateral, rotation and isotropic irradiation geometries. The results calculated here were compared with those reported in previous studies such as those of the VIPMAN, NORMAN05, MASH-3 and ICRP reference voxel phantoms. Our data shows that adding proper adipose or muscle layers to two very different phantoms can cause similar effective dose values, and also more than half of the organ absorbed doses have satisfactory agreement.

Dans le but d’obtenir le déclassement de l’installation nucléaire de base 106 (INB 106), trois de ses accélérateurs ont été arrêtés puis démantelés et un autre modifié pour passer sous le seuil de classement INB. Le démantèlement a été mené sur la base d’une stratégie de démontage mécanique sans découpe. Les éléments de génie civil peu activés ont pour la très grande majorité été laissés en place sans traitement avec des mesures compensatoires de protection du public et de l’environnement. Le résultat global de ces opérations est un gain en termes de coût et de délais et une importante diminution des risques notamment radiologiques, l’impact du site à l’état final restant acceptable.

Beach Sand Mining (BSM) is a profitable industry earning a sizable income for the country by way of foreign exchange. The Indian coast is rich in rare earths such as ilmenite, rutile, leucoxene, zircon, garnet and sillimanite, and is invariably associated with radioactive monazite. Due to the nature of the separation processes involved and the manual handling, workers in these factories are continuously being exposed to suspended particles containing naturally occurring radioactive materials. An attempt was made to estimate DNA damage using a chromosome aberration assay to monitor radiation effects in workers of BSM industries in India. The study group comprised 27 BSM workers and 20 controls. Percentage yields of dicentrics, acentric fragments and chromatid breaks observed in the control group were 0.058 ± 0.017, 0.073 ± 0.03 and 0.22 ± 0.112, respectively. Percentage yields of dicentrics + centric rings, acentric fragments and chromatid breaks observed in the BSM group were 0.029 ± 0.01 (P value 0.19), 0.24 ± 0.06 (P value 0.006) and 0.455 ± 0.06 (P value 0.0004), respectively. Elevated levels of fragments and chromatid aberrations are suggestive of low-dose radiation effects and also chemically-induced DNA damage.

The activity concentrations of soil, water and fertilizer samples were determined by using high-resolution gamma spectrometry (HPGe detector: 40% relative efficiency) with a PC-based MCA system. The samples were collected from the area of a urea fertilizer factory, lagoon and Shitalakhya river in Narsingdi, Bangladesh. The activity concentrations of 226Ra ranged from 3.16 ± 0.32 to 10.28 ± 0.55 Bq.kg-1, 1.22 ± 0.41 to 7.36 ± 0.42 Bq.L-1 and 3.55 ± 0.33 to 90.65 ± 3.17 Bq.kg-1 for soil, water and fertilizer samples, respectively. The 232Th activity concentrations ranged from 4.89 ± 0.45 to 15.82 ± 0.45 Bq.kg-1, 1.21 ± 0.06 to 8.59 ± 0.37 Bq. L-1 and 4.76 ± 0.25 to 26.38 ± 1.40 Bq.kg-1 for soil, water and fertilizer samples, respectively. The 40K activity concentrations ranged from 24.96 ± 0.23 to 60.49 ± 0.56 Bq.kg-1, 7.48 ± 0.53 to 35.48 ± 0.24 Bq.L-1 and 3.55 ± 0.05 to 3051.71 ± 19.53 Bq.kg-1 for these samples, respectively. The radium equivalent activity, the hazard indices, the gamma activity concentration index, the indoor absorbed dose rate and the corresponding annual effective dose were estimated for the potential radiological hazard of the collected samples. The calculated values of the representative level index values (Igr) for all samples of the study area are lower than unity except the MOP sample. The activity ratios were also measured. These values are compared with reported values for other countries of the world. The results of the comparison studies show that the radioactivity concentrations and other radioactive indices of the samples of the study area are below the internationally accepted maximum permissible values. Therefore, this region is safe from any radiation hazard and no significant radiological threat was observed to the population of the study area.