CHERPAC is a code developed by AECL to predict the time-dependent concentrations of 25 radionuclides in environmental compartments and the resulting radiation dose (ingestion, inhalation, immersion and groundshine) to humans, following an accidental release to the atmosphere from a nuclear facility. CHERPAC was used to investigate environmental sensitivities in agricultural and forest ecosystems. Given the assumptions in the CHERPAC code, it was concluded that doses to humans from agricultural food products are higher than those from groundshine and forest food products. Doses from agricultural products are highest from radionuclide deposition in summer because all plants are at their peak growth and are ingested fresh after the deposition event. The dose is higher if the deposition occurs in dry conditions rather than during heavy rain, because radionclides adhere better to dry plant leaves. For Cs-137, ingestion dose is higher for adults than other age groups, but for Sr-90 and I-131, ingestion dose is highest for infants. This is due to relative food product concentrations, intake rates and DCFs (dose conversion factors). In the forest ecosystem, adult doses are higher than those for children and infants because of the higher rates of intake by adults of forest food products.

Model intercomparison exercises have identified radionuclide transfer predictions as the greatest source of uncertainty in biota dose assessments. One wildlife group for which few transfer data exist is reptiles, Given that reptiles are an important, and often protected, component of many ecosystems and that assessments of radiation impact on ecosystems are becoming increasingly necessary due to the current nuclear renaissance, there is a need to further develop our current database on transfer to reptiles or find alternative approaches to estimate reptile transfer parameters. Three approaches that have the potential to increase the availability of parameters to predict radionuclide transfer to reptiles are the use of non-lethal sampling techniques, phylogenetic relationships and allometric relationships. Non-lethal sampling is an attractive long term option for deriving transfer parameters, but the derivation of phylogenetic and allometric relationships could provide ways of predicting transfer in the interim.

Since January 1959, Health Canada has monitored environmental levels of radioactive fallout, to ensure the health and well being of Canadians. This work has evolved to include explosion verification for the Comprehensive nuclear-Test-Ban Treaty by monitoring the concentration of radioxenon in the atmosphere. Detection of Xe at Yellowknife by the monitoring system of Health Canada combined with the atmospheric transport and dispersion models (ATDM) of Environment Canada and seismic timing data have shown that the source of this Xe was most likely from the North Korean nuclear test of October 9th, 2006. Historical and real time monitoring data on the distribution of Xe releases from Chalk River Labs, the major source of anthropogenic background to Yellowknife were studied. Careful review of other large Xe-133 measurements at Yellowknife with ATDM was used to understand the October 2006 measurements of Xe. This allowed us to conclude that the Xe-133 detected at Yellowknife could be attributed to a release from the October nuclear test in North Korea. Health Canada and Environment Canada have demonstrated that Xe detection combined with ATDM is a viable technology for treaty verification.

Although aim of the environmental protection is conservation of ecosystem, there are only a few studies focusing on the effect of radiation on ecosystem. To understand the ecological effect of irradiation, microbial ecosystem, “microcosm”, which contains minimum components of ecosystem such as producer, consumer and decomposer, is useful because the natural ecosystem is too complex. The microcosm consists of three species, i.e. Euglena (producer), Tetrahymena (consumer), and E. coli (decomposer). The mathematical model and computer simulation model were also developed to understand the mechanism of ecological interaction using the results of acute exposure experiments of the microcosm, and we predicted Tetrahymena, which is the most radio-resistant among the constituent species, would be most sensitive in the chronically irradiated microcosm as a result of an indirect effect due to population decrease in E. coli. Recently we started chronic exposure experiments. The microcosms were irradiated with γ-rays at dose rate of 1.2Gy/day, 5Gy/day, 10Gy/day and 23Gy/day. From preliminary results, we found that the prediction from the models was different from the experimental results. Therefore, in this study, we improved our mathematical model and discuss the difference between the model and experiments.

This paper describes transport modeling performed by the Swedish Nuclear Fuel and Waste Management Company (SKB) within the recently completed SR-Site safety assessment. SR-Site is a part of the license application for building a deep geological repository for spent nuclear fuel in Sweden; this application was submitted to the authorities in March 2011. In the safety assessment, a suite of transport models was used to quantify radionuclide transport through the engineered and geological barriers and in the biosphere. The present paper is focused on the transport in the upper part of the bedrock and in the regolith (the Quaternary deposits overlying the rock). The results presented provide input to the assessment of uncertainties in calculated discharge locations for radionuclide-bearing groundwater from the considered repository volume and to analyses of solute spreading in near-surface and surface systems.

Chlorine 36 is considered as part of the group III of radioactive wastes composed of the moderate radiotoxic radionuclides such as Carbon 14. As such and along with its long half-life (3.01 × 105 years) and its chemical form (chloride anion), it is a very important radionuclide to be taken into account in the environment thereby making its modelling an important goal.

We present in this paper the phenomenological approach developed at IRSN for modelling the behaviour of chloride 36 in the continental ecosystems. This model is a part of the SYMBIOSE programme (SYstemic approach for Modelling the fate of chemicals in the BIOSphere and the Ecological systems) whose main goal is to develop a modelling platform able to sustain an environmental chemical risk assessment. Such an approach has been found necessary for Chlorine 36 when the classic models (conventional transfer factor models and specific activity models) fail (for instance in case of acute release of radionuclides). Only the part of the model dealing with the agricultural soil-plant system is described here in detail: interaction matrices, components description, components equations, independent variables, and data. Then, we present an application of this model to investigate chlorine 36 behaviour in soils and uptake by plants after its discharge in groundwater from a radioactive waste deep storage site. Finally, we present results from an intercomparison study performed under the BIOPROTA international cooperation framework.

The comparison of strength of bystander effect induction in human lymphocytes by rho0 (complete loss of mitochondrial DNA) and rho+ (with fully functional mtDNA) strains of Saccharomyces cerevisiaewas carried out. The cultures of human peripheral blood were experimentally contaminated with nonirradiated or X-ray irradiated yeast cells (haploid rho0 and rho+ strains of S. cerevisiae). The doses of irradiation were 1 and 10 Gy. Well spread human metaphases were scored for chromosomal aberrations (CA). It was found that nonirradiated yeast cells (no matter rho0 or rho+) had no effect on lymphocytes chromosomal stability. Statistically significant increased level of CA was observed in lymphocytes incubated with irradiated rho+ yeast cells. The increasing of the CA was dose independent. However, after cocultivation with irradiated rho0 cells the bystander effect was revealed for dose 10 Gy only and his manifestation was mild in comparison with rho+ data. Thus, our findings suggest that strength of bystander effect depends on existence of mitochondrial DNA and normally functioning mitochondria.

The uptake of radioceasium and radiostrontium in biota in dose assessment models is mostly estimated on the basis of Concentration Factors (CF). For accidental releases, the dynamical foodweb model BURN has been implemented in the coastal model POSEIDON (part of the Decision Support System RODOS). BURN can be applied on water bodies with different salinity levels, since in the model the uptake of radioceasium and radiostrontium in phytoplankton is governed by potassium and calcium in the water, which are calculated via the easier-to-obtain parameter salinity. Recently a dataset on radiocaesium and radiostrontium has been collected for various aquatic organisms in the Dnieper-Bug Estuary (DBE) in Ukraine, which enabled model validation with BURN. Considering the limitation of compartment models and the fact BURN is a predictive model, with fixed model parameters, the model results are within a reasonable range with the measurement data. Besides comparison with measurement data, the model calculations were also used to derive values for CF and compared with literature, which gave reasonable results for Cs-137 in fish and molluscs. For Sr-90 however, the calculated values exceeded the levels given in literature, since equilibrium between radionuclides in biota and water is not reached. Longer time periods for the radionuclide flux into the DBE, both from the Dnieper and the Black Sea are required to obtain high quality model results for the years after 1989.

The complex radioecological investigations of the East-Ural Radioactive Trace were conducted. Three transects were established in EURT area: central, eastern and western. The current levels of soil contamination near the epicenter of the accident reach 30 × 103 kBq/m2 for 90Sr and 1 × 103 kBq/m2 for 137Cs. Contamination levels are reduced in accordance with a power function with increasing distance from the accident site and at a distance of more than 100 km become close to background values. In the EURT impact area vegetation is a complex of synanthropic and semi-natural plant communities in various stages of degradation and restoration successions. The current state of phytocenosises on the sites of the demolished local villages is largely determined by the degree of human impact in the pre-accident period, and remediation activities. For most species the viability of their seed progeny, formed in a gradient of radioactive contamination, are either not different from background samples or reduced half a century after the accident. Mutability of seed progeny in impact coenopopulations in all studied species was high. Radioadaptation phenomenon, i.e. increased resistance to provocative irradiation is rare and unstable.

The Yenisey River belongs to one of the main Siberian water systems flowing into the Arctic basin. Technogenic radionuclides have entered this system due to activities at the Krasnoyarsk Mining and Chemical Combine (KMCC), situated approximately 40 km downstream from the city of Krasnoyarsk (Zheleznogorsk), which began operations in August of 1958 (start-up of the first straight-through reactor, a second reactor was operated from 1961). In the period of 1958 to 1992 the river channel and flood plain were exposed to contamination at great distances downstream from the waste discharge point. Various long-lived radionuclides were measured in the environment such as 137Cs, 60Co, 152Eu, 154Eu with half-lives of 30.2, 5.3, 13.3 and 8.6 years correspondingly. Both reactors were decommissioned in 1992 and since then radionuclide discharges to the river have decreased by several tens of times.

Although some radioecological studies have been accomplished in Brazilian soils supplying useful information to optimization of emergency planning actions in rural areas and to the management of soils contaminated by 137Cs, 60Co and 90Sr, few studies were made with transuranic elements in tropical agricultural areas. The different scenarios found in Brazilian agricultural environments enhance the importance of studying the biogeochemical behavior of radionuclides in representative soils. The objective of this work was to determine the mobility of 241Am in 3 different Brazilian agricultural soils evaluating migration with depth and Kd values for 241Am and the effect of organic amendments on this behavior. A strong effect of organic amendments on mobility of americium could be observed. The values of Kd obtained in all studied tropical soils were however smaller than those found in European soils and from those recommended by IAEA to be used as default values in the absence of regional data. This result reinforces the vulnerability of some tropical soils to a contamination, emphasizing the need to use of regional values.

European computerised decision support systems are currently targeted for large accidental atmospheric contaminant releases from nuclear installations. To make these systems applicable also for malicious dispersion events, such as ‘dirty bomb’ blasts, a series of modifications and extensions are necessary. Also European decision support handbooks need supplementary sections to cover the features of these types of scenarios. An overview is given of the requirements.

The area affected by the Chernobyl accident has become a unique test site where long-term ecological and biological consequences of a drastic change in a range of environmental factors as well as trends and intensity of selection are studied in natural settings. The consequences of the Chernobyl accident for biota varied from an enhanced rate of mutagenesis to damage at the ecosystem level. The severity of radiation effects was strongly dependent on the dose received in the early period after the accident. The most exposed phytocenoses and soil animals’ communities exhibited dose dependent alterations in the species composition and reduction in biological diversity. These findings make a valuable contribution to scientific and public understanding of the environmental risks of ionizing radiation and to debates on the environmental costs, benefits and risks of nuclear energy.

The Urban Areas Working Group is part of the International Atomic Energy Agency’s EMRAS II (Environmental Modelling for Radiation Safety) Programme. The goal of this Working Group is to test and improve the capabilities of models used in assessment of radioactive contamination in urban settings, including dispersion and deposition events, short- and long-term contaminant redistribution following deposition events, and potential countermeasures or remediation efforts for reducing human exposures and doses. The Working Group has developed three modeling exercises, which are designed to permit intercomparison of model predictions and, in one case, comparison of model predictions with measurements. This paper describes the scenarios and provides comparisons of initial modeling results. Reasons for similarities and discrepancies among model predictions are discussed in terms of the modeling approaches, models, and parameter values used by different assessors. Preliminary conclusions emphasize the value of explaining individual approaches and the importance of understanding the effects of different assumptions and parameter values on the modeling results.

Over the last 5 years France gained a feedback on its NORM industries situation. Regulation imposes to the operators to assess effective doses for workers and members of the public. Theses data were used to update the list of industrial sectors to be regulated for NORM use or storage.

Over the last 20 years, the French public services’ actions in the field of polluted areas have continuously evolved from the inventory of potentially polluted areas to the statement of a general framework on the management. Initially designed for chemical pollutants, main guidelines have been implemented for radioactive substances. The general framework is presented hereafter and illustrated with a real example.

A multi-step project has been developed by eni r&m to define a TENORM (Technologically Enhanced Naturally Occurring Radioactive Material) management system in refinery plants, compliant with Italian regulations and international guidelines.

The project involves a preliminary survey on refineries to detect, on the basis of the production process, the sections at risk of TENORM accumulation; this analysis is followed by the consequent formation/information to the workers, dose assessment for workers and the public, introduction of radiometric characterization before release of potentially contaminated waste.

Radioactive releases in the environment around civilian nuclear facilities have significantly decreased over the last few decades, with the exception of tritium. In late 2007, papers published in the UK (RIFE 11 report, study by the HPA’s Advisory Group on Ionising Radiation (AGIR)) raised questions as to the behaviour of tritium in the environment. Given this context, ASN wanted to get a clear analysis of the existing studies into the issue and in early 2008 decided to establish two independent pluralistic working groups. Two main points of the discussions are on the bioaccumulation and the biological effects.

In the end of 2007, ASN launched an internal reflexion on the information of the public on the radioactivity levels in the environment. The aim was to develop a radioactivity environment scale or index, based on existing scales used for air pollution. After the presentation of a demonstration model by ASN in 2008 to HCTISN, a working group (WG) was constituted in the beginning of 2009 by ASN with stakeholders with the approval in March 2009 of the goals to be reached by this index: a communication instrument to qualify the information of the radioactivity levels in the environment, consistent with INES, particularly when sanitary consequences may occur, easy to elaborate from the available measured values of radioactivity and always usable for any location, independently of an incidental or accidental situation.

One challenge in the analysis of far future radiological effects of a deep geological repository is to handle changes in time on ecosystems potentially affected. Under Swedish regulations, the time span that needs to be assessed is 100,000 yrs or more. This has historically been treated by using a reference biosphere that, in short, takes into account the total data range of the site properties that may change with different climates and sites. One problem with this strategy has always been to show that these reference biospheres have relevance for a specific site. To overcome this problem, SKB has adopted a strategy that uses site specific information together with scientific literature to build a narrative. This narrative describes the site development during a 100,000-yrs period (time frame of the present global glacial cycle). The information is used to compile a number of models that describe how the succession of abiotic and biotic features and their properties will develop at the site. The resulting Landscape Development Model is finally used in two ways: to tell the narrative of the site development based on scientific understanding and interdisciplinary consensus, and to populate the Radionuclide Model that is used to describe the effects of released radionuclides in a changing environment.