A fast long-range transport model for operational use in episode simulation. Application to the Chernobyl accident

137Cs contamination over Transylvania region (Romania) after Chernobyl Nuclear Power Plant Accident

Following the radionuclide releases due to Chernobyl Nuclear Power Plant accident, various studies were completed by researchers all over the world in order to measure the surface contaminations by artificial radionuclides. The aim of this study was to evaluate ¹³⁷Cs surface contamination and to create an inventory distribution for Transylvania region (Romania) after the Chernobyl event using γ spectrometric measurements on soil samples collected from 153 locations. The results were compared to measured data from the Danube Delta and Moldova Republic, as well as to ¹³⁷Cs concentrations from the rest of Europe reported by literature. The ¹³⁷Cs surface concentrations in soil samples ranged between 0.4±0.1kBqm^-2 and 301.1±3.0kBqm^-2, having an average of 8.3±0.2kBqm^-2, with more elevated values in the mountain areas (18.3±0.6kBqm^-2) compared to the hills and plains (2.6±0.1kBqm^-2). Taking into consideration the cardinal regions, the northern and western regions received the least amount of ¹³⁷Cs (2.9±0.1kBqm^-2), while the southern part received 16.3±0.6kBqm^-2. Sampling points with eastern slope exposure received the highest average (27.8±0.5kBqm^-2), while southern, north-western and north-eastern ones received less than 8kBqm^-2. Two hotspots are reported at Iezer-Ighiel (72.7±5.9kBqm^-2) and Tulgheș areas (51.5±0.6kBqm^-2).

Global transport and deposition of 137Cs following the Fukushima nuclear power plant accident in Japan: emphasis on Europe and Asia using high-resolution model versions and radiological impact assessment of the human population and the environment using interactive tools

The earthquake and the subsequent tsunami that occurred offshore of Japan resulted in an important loss of life and a serious accident at the nuclear facility of Fukushima. The "hot spots" of the release are evaluated here applying the model LMDZORINCA for (137)Cs. Moreover, an assessment is attempted for the population and the environment using the dosimetric scheme of the WHO and the interactive tool ERICA, respectively. Cesium-137 was deposited mostly in Pacific and Atlantic Oceans and North Pole (80%), whereas the rest in the continental areas of North America and Eurasia contributed slightly to the natural background (0.5-5.0 kBq m(-2)). The effective dose from (137)Cs and (134)Cs (radiocesium) irradiation during the first 3 months was estimated between 1-5 mSv in Fukushima and the neighboring prefectures. In the rest of Japan, the respective doses were found to be less than 0.5 mSv, whereas in the rest of the world it was less than 0.1 mSv. Such doses are equivalent with the obtained dose from a simple X-ray; for the highly contaminated regions, they are close to the dose limit for exposure due to radon inhalation (10 mSv). The calculated dose rates from radiocesium exposure on reference organisms ranged from 0.03 to 0.18 μGy h(-1), which are 2 orders of magnitude below the screening dose limit (10 μGy h(-1)) that could result in obvious effects on the population. However, these results may underestimate the real situation, since stable soil density was used in the calculations, a zero radiocesium background was assumed, and dose only from two radionuclides was estimated, while more that 40 radionuclides have been deposited in the vicinity of the facility. When monitoring data applied, much higher dose rates were estimated certifying ecological risk for small mammals and reptiles in terms of cytogenetic damage and reproduction.