RESUMEN
Over the last four decades, the dose conversion factors used to calculate external exposure to γ radiation from soil from (40)K and the (226)Ra and (232)Th chains have been 0.62, 0.042 and 0.46 (nGy/h per Bq/kg), respectively. This work updates these γ-to-dose conversion factors, taking into consideration the composition, depth and radius of the soil source, and importantly, updated branching ratios, with MCNPX simulations. The new conversion factors are 0.036, 0.357 and 0.482 (nGy/h per Bq/kg) for (40)K and the (226)Ra and (232)Th chains, respectively.
Asunto(s)
Rayos gamma , Dosis de Radiación , Contaminantes Radiactivos del Suelo/análisis , Modelos Teóricos , Monitoreo de RadiaciónRESUMEN
Following the Fukushima nuclear accident, low-background gamma spectrometry measurements were performed with HPGe detectors at the PRISNA platform located at the CENBG laboratory in Bordeaux, France. Different kinds of samples were collected and measured between March 26 and May 14, 2011. The first fission product observed was (131)I with maximum activity values of 2.4 mBq/m(3) in atmospheric dusts in air, 3.5 Bq/L in rain water, 15 Bq/kg in grass and 0.9 Bq/L in cow milk. The (134,137)Cs isotopes were also detected in air and in grass at a maximum level of 0.2 mBq/m(3) and 0.7 Bq/kg respectively, around one order of magnitude less than (131)I activity, but they were below detection limits in the other samples. All these activity values were consistent with others measured in France by IRSN and were well below those reported in May 1986 after the Chernobyl accident.
Asunto(s)
Radioisótopos de Cesio/análisis , Accidente Nuclear de Fukushima , Radioisótopos de Yodo/análisis , Contaminantes Radiactivos/análisis , Animales , Polvo/análisis , Contaminación Radiactiva de Alimentos/análisis , Francia , Japón , Leche/química , Poaceae/química , Monitoreo de Radiación , Lluvia/químicaRESUMEN
We report results from the NEMO-3 experiment based on an exposure of 1275 days with 661 g of (130)Te in the form of enriched and natural tellurium foils. The ßß decay rate of (130)Te is found to be greater than zero with a significance of 7.7 standard deviations and the half-life is measured to be T(½)(2ν) = [7.0 ± 0.9(stat) ± 1.1(syst)] × 10(20) yr. This represents the most precise measurement of this half-life yet published and the first real-time observation of this decay.
RESUMEN
Imaging plate (IP) radiation detectors are widely used in industrial radiography, medical imagery and autoradiography. When an IP is exposed to ionising radiation, some of the energy is absorbed to form a latent image. The energy stored, which is proportional to the dose received, can be liberated by a selective optical stimulation and collected to reconstitute the distribution of the ionising radiation on the IP. In this work, IPs for use in fast-neutron measurements are characterised. The response of our IP dosemeters in conjunction with their reading system was found to be linear in dose between 75 microSv and 10 mSv. This performance is compared with those of dosemeters based on the plastic track detectors PN3 and CR-39.