Preparedness of households and catering establishments for incidents involving radioactive contamination

This short paper describes a number of investigations carried out to ensure preparedness for crises involving radioactivity to catering operations and private households in Finland. The specific recommendations for catering kitchens during crises were published in 1994. A study to determine the level of adherence to these recommendations is summarised here, together with its findings and subsequent recommendations. Another study on the pre-planning of crisis menus is described. New challenges for the catering kitchens are touched upon. A crisis food preparation booklet for households is described and based on consumers' attitudes suggestions are made for how this can be improved in the future.     

Significant radioactive contamination of soil around a coal-fired thermal power plant

Soil samples were collected around a coal-fired power plant from 81 different locations. Brown coal, unusually rich in uranium, is burnt in this plant that lies inside the confines of a small industrial town and has been operational since 1943. Activity concentrations of the radionuclides 238U, 226Ra, 232Th, 137Cs and 40K were determined in the samples. Considerably elevated concentrations of 238U and 226Ra have been found in most samples collected within the inhabited area. Concentrations of 235U and 226Ra in soil decreased regularly with increasing depth at many locations, which can be explained by fly-ash fallout. Concentrations of 235U and 226Ra in the top (0-5 cm depth) layer of soil in public areas inside the town are 4.7 times higher, on average, than those in the uncontaminated deeper layers, which means there is about 108 Bq kg(-1) surplus activity concentration above the geological background. A high emanation rate of 222Rn from the contaminated soil layers and significant disequilibrium between 238U and 226Ra activities in some kinds of samples have been found.     

Genetic consequences of radioactive contamination by the Chernobyl fallout to agricultural crops

The genetic consequences of radioactive contamination by the fallout to agricultural crops after the accident at the Chernobyl NPP in 1986 have been studied. In the first, acute, period of this accident, when the absorbed dose was primarily due to external beta- and gamma-irradiation, the radiation injury of agricultural crops, according to the basic cytogenetic tests, resembled the effect produced by acute gamma-irradiation at comparable doses. The yield of cytogenetic damage in leaf meristem of plants grown in the 10-km zone of the ChNPP in 1987-1989 (the period of chronic, lower level radiation exposure) was shown to be enhanced and dependent on the level of radioactive contamination. The rate of decline with time in cytogenetic damage induced by chronic exposure lagged considerably behind that of the radiation exposure. Analysis of genetic variability in three sequential generations of rye and wheat revealed increased cytogenetic damage in plants exposed to chronic irradiation during the 2nd and 3rd years.     

Mesoscale modelling of radioactive contamination formation in Ukraine caused by the Chernobyl accident

This work is devoted to the reconstruction of time-dependent radioactive contamination fields in the territory of Ukraine in the initial period of the Chernobyl accident using the model of atmospheric transport LEDI (Lagrangian-Eulerian DIffusion model). The modelling results were compared with available 137Cs air and ground contamination measurement data. The 137Cs atmospheric transport over the territory of Ukraine was simulated during the first 12 days after the accident (from 26 April to 7 May 1986) using real aerological information and rain measurement network data. The detailed scenario of the release from the accidental unit of the Chernobyl nuclear plant has been built (including time-dependent radioactivity release intensity and time-varied height of the release). The calculations have enabled to explain the main features of spatial and temporal variations of radioactive contamination fields over the territory of Ukraine on the regional scale, including the formation of the major large-scale spots of radioactive contamination caused by dry and wet deposition.     

Intrapopulation variation in the quality of dandelion seed progeny in zones of chemical and radioactive contamination

Interfamilial variation in metal tolerance and radioresistance of seed progeny from F ₁ plants was studied in the dandelion from cenopopulations growing over several decades in gradients of radioactive or chemical contamination. The progeny from the impact zone of the Eastern Ural Radioactive Trace (EURT) proved to be highly viable but had latent injuries that accounted for a high sensitivity to additional technogenic impact. In the F ₁ generation from the zone of chemical contamination, high seed viability was combined with increased tolerance to additional impact of radiation and heavy metals. No significant differences between responses to challenge with habitual and new factors were revealed in samples from either zone.     

Reconstruction of (131)I radioactive contamination in Ukraine caused by the Chernobyl accident using atmospheric transport modelling

The evaluation of (131)I air and ground contamination field formation in the territory of Ukraine was made using the model of atmospheric transport LEDI (Lagrangian-Eulerian DIffusion model). The (131)I atmospheric transport over the territory of Ukraine was simulated during the first 12 days after the accident (from 26 April to 7 May 1986) using real aerological information and rain measurement network data. The airborne (131)I concentration and ground deposition fields were calculated as the database for subsequent thyroid dose reconstruction for inhabitants of radioactive contaminated regions. The small-scale deposition field variability is assessed using data of (137)Cs detailed measurements in the territory of Ukraine. The obtained results are compared with available data of radioiodine daily deposition measurements made at the network of meteorological stations in Ukraine and data of the assessments of (131)I soil contamination obtained from the (129)I measurements.     

Preliminary evaluation of (135)Cs/(137)Cs as a forensic tool for identifying source of radioactive contamination

Ratios of the fission products (135)Cs and (137)Cs were determined in soil and sediment samples contaminated from three different sources, to assess the use of (135)Cs/(137)Cs as an indicator of source of radioactive contamination. Soil samples from the Chernobyl exclusion zone were found to have to be heavily depleted in (135)Cs ((135)Cs/(137)Cs approximately 0.45), indicative of a high thermal neutron flux at the source. Sludge samples from a nuclear waste treatment pond were found to have a (135)Cs/(137)Cs ratio of approximately 1, whereas sediment collected downstream from a nuclear reactor was highly variable in both (137)Cs activity and (135)Cs/(137)Cs ratio. Comparison of these preliminary results of variability in radiocaesium isotope ratios with reports of Pu isotope ratios suggests (135)Cs/(137)Cs similarly varies with fuel and reactor conditions, and may be used to corroborate other methods of characterizing radioactive contamination.     

Radioactive contamination in the marine environment adjacent to the outfall of the radioactive waste treatment plant at ATOMFLOT,northern Russia

RTP "ATOMFLOT" is a civilian nuclear icebreaker base located on the Kola Bay of northwest Russia. The objectives of this study were to determine the distributions of man-made radionuclides in the marine environment adjacent to the base, to explain the form of the distributions in sediments and to derive information concerning the fate of radionuclides discharged from ATOMFLOT. Mean activity concentrations (d.w.) for surface sediment, of 63 Bq kg(-1 137Cs, 5.8 Bq kg(-1) 90Sr and 0.45 Bq kg(-1 239,240)Pu were measured. Filtered seawater activity levels were in the range of 3--6.9 Bq m(-3) 137Cs, 2.0-11.2 Bq m(-3) 90Sr, and 16-40 m Bq m(-3), 239,240Pu. Short-lived radionuclides were present at sediment depths in excess of 10cm indicating a high degree of sediment mixing. Correlations of radionuclide activity concentrations with grain-size appear to be absent; instead, the presence of relatively contaminated sediment appears to be related to the existence of radioactive particles.     

Residual radioactive contamination at the peaceful underground nuclear explosion sites "Craton-3" and "Crystal" in the Republic of Sakha (Yakutia)

In this paper, results are reported on the concentrations and activity ratios of 137Cs, 239+240Pu and 238Pu in soils, lichen and bottom sediments collected at the peaceful underground nuclear explosion sites "Craton-3" and "Crystal" (Republic of Sakha (Yakutia), North-East Siberia). At the "Craton-3" site, 239- 240Pu concentrations in the range 6.2 mBq/g to 5.9 Bq/g in surface soils (0-5 cm) and 239+240Pu concentrations up to 7.4 Bq/g in lichen were observed. The 137Cs concentration in measured soils range from 0.52 to 216 Bq/g for the near-plume and from 1.65 to 21.5 Bq/g for the far-plume. In lichen, 137Cs concentration varied from a global background level up to 251 Bq/g. Radioactive contamination at "Crystal" demonstrates an extremely irregular distribution of 239,240Pu and 137Cs in environmental samples taken at locations within 150 m radius of the site. Further work on compiling detailed maps of radioactive contamination of the territory around "Craton-3" and "Crystal" is discussed.     

Attitude of a group of Belgian stakeholders towards proposed agricultural countermeasures after a radioactive contamination: synthesis of the discussions within the Belgian EC-FARMING group

In the case of radioactive contamination of the environment with an impact on the food chain, the remediation strategy will not only be based on scientific knowledge and technical experience, but will also be dictated by peculiarities of the country. These characteristics include the agro-industrial structure, the local and international economical contexts and the political configuration including the distribution of responsibilities and competencies. This paper identifies and illustrates the most relevant characteristics of the Belgian agricultural system and political environment; it also describes the past experience with food chain contamination, which is expected to influence the attitude of Belgian stakeholders, who would be involved in the setting up of countermeasure strategies for maintaining agricultural production and food safety. The picture drawn explains why several countermeasures aiming to reduce the contamination in food products, although scientifically sound and technically feasible, are hardly acceptable or even not acceptable at all, to the stakeholders.     

Ant species composition and richness in different types of semi-natural grasslands

The distribution of ant species was studied across different types of semi-natural grasslands in a mosaic landscape in which data on land use history and conservation values were available. The twenty-nine grasslands selected were non-fertilised and had an uninterrupted history of management, but they differed from each other in soil texture and grazing practices and were therefore sub-divided into six different types. Species abundance of mound-building ants were investigated in these grasslands in 2003. Additionally, ants were sampled using the pitfall trapping method in 13 semi-natural grasslands (in 2003 and 2005). Ant species richness and nest frequency of individual ant species differed between the different types of grassland and was associated with soil texture and grazing practices. The results also showed that even small grasslands have a very high ant species richness. This study showed that for the conservation of ants, habitat diversity and heterogeneity rather than habitat size are of great importance. I conclude that different types of semi-natural grassland contribute to heterogeneity in the farmland landscape and, thus, support higher ant diversity at the landscape scale.     

Radioactive contamination of wood and its products

This paper presents research on radioactive contamination of the three most common kinds of wood in Croatia--beech, oak and fir as well as acorn. Gamma-spectrometric measurements carried out on the samples of bark and wood of beech, oak, fir and acorn have shown radioactivity contents ranging from 1.6 +/- 0.1 to 37.3 +/- 0.5 Bq/kg from deposited 137Cs, whose concentrations in the soil of Croatia have increased after the Chernobyl accident. Measurements have also shown the radioactivity originating from 40K and 214Bi, which are part of the natural composition of the soil. The distribution of the radionuclides in wood has been discussed, as well as the impact of radioactive contamination of wood by the artificial radionuclide 137Cs upon the forest ecosystem. According to the corresponding model, it has been calculated that a 10 h daily stay in a typical family house increases the annual radiation dose of the population, due to the deposited 137Cs in the structure or furniture, by 343 microSv.     

Long-term dynamics of radioactive <Superscript>90</Superscript>Sr and <Superscript>137</Superscript>Cs contamination of small mammals in the Chernobyl zone

Between 1986 and 1994, a decrease in nonalimentary ⁹⁰Sr and ¹³⁷Cs intake and changes in the accessibility of radionuclides in the soil-plant link of their cycle resulted in a 10-to 100-fold decrease in their specific activity (SA) in the bodies of small mammals inhabiting the Chernobyl zone, and a similar decrease was observed in the radionuclide transition factor (TF) in the soil-animal chain. Between 1995 and 2005, no consistent increase or decrease in SA or TF could be revealed against the background of a combined effect of different physicochemical and ecological factors. It is suggested that subsequent changes in the level of radioactive contamination of small mammals will generally reflect only the dynamics of physical ⁹⁰Sr and ¹³⁷Cs decay, but, nevertheless, seasonal and local variations in this level will be significant.     

Modelling of a large-scale urban contamination situation and remediation alternatives

The Urban Remediation Working Group of the International Atomic Energy Agency's EMRAS (Environmental Modelling for Radiation Safety) program was organized to address issues of remediation assessment modelling for urban areas contaminated with dispersed radionuclides. The present paper describes the first of two modelling exercises, which was based on Chernobyl fallout data in the town of Pripyat, Ukraine. Modelling endpoints for the exercise included radionuclide concentrations and external dose rates at specified locations, contributions to the dose rates from individual surfaces and radionuclides, and annual and cumulative external doses to specified reference individuals. Model predictions were performed for a “no action” situation (with no remedial measures) and for selected countermeasures. The exercise provided a valuable opportunity to compare modelling approaches and parameter values, as well as to compare the predicted effectiveness of various countermeasures with respect to short-term and long-term reduction of predicted doses to people.     

Monitoring of radionuclides contamination of soils in Shatsk National Natural Park (Volyn region, Ukraine) during 1994-2001

The results of studies of radionuclide contamination of the soils in the western part of the territory of Shatsk National Natural Park (ShNNP), Volyn region, Ukraine, performed during 1994-2001 are presented. Based on the experimental results, the three-dimensional plot of the 137Cs density contamination for the soils at the territory under investigation has been constructed. The monitoring during 1994-2001 of the 137Cs vertical distributions in the different kinds of soils from the Park and the forecasting of the distribution changes of the depth down to 50 cm for the sod loamy sandy gleyed loamy sand soil of the Park up to 2086 have been performed.