A screening ecological risk assessment was performed for regulatory compliance at two Ontario nuclear power generation station sites to establish design requirements for a contaminant-monitoring program and to address the need for non-contaminant stressor management. Site-specific assessments went beyond traditional contaminant risk assessment to include stressors associated with land-use change, cooling water systems and site storm water runoff. Valued terrestrial and aquatic ecosystem components were selected from species lists after stakeholder consultation, and contaminants of concern were selected based on their relative loadings, and with respect to regulatory and literature-based benchmarks. Predictive modeling was used to estimate chemical and radionuclide exposures and likelihood of effects. Potential adverse effects on biota were predicted for aqueous emissions of chlorine and storm water but not for radionuclides. Retrospective analyses of field monitoring were used to determine likelihood of effects from non-contaminant stressors. Individual-level adverse effects were observed for fish losses from cooling water intake. Depending on the site and the biological species, either beneficial or adverse effects from thermal discharge were observed. Follow-up studies include monitoring, laboratory study, computer modeling and mitigation. Field monitoring will generate more precise species-level estimates of intake fish losses, magnitude of fish response to thermal discharge and chlorine concentrations in near-field discharge waters. Laboratory study is determining the effectiveness of intake fish loss mitigation technology. Computer fish population models are being used to design field studies and interpret individual-level effects. Mitigation includes storm water controls and habitat biodiversity management projects to offset past losses from site development and construction. Contaminant monitoring is planned to collect necessary information to verify site specific risk assessment model predictions and confirm model parameters and assumptions. The updated contaminant risk assessment models will be used to adjust site monitoring programs.

The BioMoSA (Biosphere Models for Safety Assessment of Radioactive Waste Disposal) project was part of the EC fifth framework research program. The main goal of this project was the improvement of the scientific basis for the application of biosphere models in the framework of long-term safety studies of radioactive waste disposal facilities. Another aim of the project was to provide operators and regulatory bodies with guidelines for performance assessments of repository systems. The study focused on the development and application of site-specific models and a generic biosphere tool BIOGEM (BIOsphere GEneric Model), using the experience from National programs and the IAEA BIOMASS reference biosphere methodology. The models were applied to 5 typical locations in Europe, resulting in estimates of the annual individual doses to the critical groups and the ranking of the importance of the pathways for each of the sites. The results of the site-specific and generic models were then compared. Uncertainty in the results was estimated by means of stochastic calculations which allowed a comparison of the overall model uncertainty with the variability across the different sites considered.

Preceding the construction of a future repository of spent nuclear fuel, a descriptive ecosystem model has to be developed in order to meet the demands set by a safety assessment. The descriptive ecosystem model should be able to describe stocks and flows of matter, and processes that may affect these on a broad landscape scale. Here we describe the planned strategy to develop such a model in three steps; the conceptual model, introduction of site-specific data and, transfer and accumulation of matter in the landscape. The suggested method is based on an ecosystem approach using site-specific data. A mass balanced ecosystem model with food webs provide a way of analysing how matter are linked to different ecosystem components through fluxes. It is suggested that estimated inflow and outflow of matter in mass balanced ecosystem units will reduce the potential variation of transport and accumulation of matter by setting the physical and biological limits to the system. In this paper we present a strategy to build a descriptive ecosystem model and shows examples from the ongoing descriptions at Forsmark and Simpevarp in the Swedish site investigation programme to illustrate the ideas.

There are many existing models describing the behaviour of carbon 14 and tritium in the environment. There are all quite difficult to handle and data consuming because they are based on the precise description of the different and complex mechanisms of the carbon and hydrogen cycles. A simplified model of transfer in the environment of tritium and carbon 14 is presented. It is based on the following assumptions: (a) the modelled radionuclides have an homogeneous repartition inside the biological compartments considered; (b) transfer flows of such radionuclides are proportional to the biomass changes in all the biological compartments; (c) time evolution of radionuclides isotopic equilibrium is discrete. Such a dynamic approach is based on the use of growth models of biological systems (plants, animals, etc..). From the proposed conceptual model, 2 mathematical models are proposed: a one-pool model (organic carbon for carbon 14) and a two-pool model (organic tritium and tritiated water for tritium).

As part of its functions, the IAEA periodically reviews the status and continued relevance of the safety standards to the needs of its Member States. Recent work is described on the development of standards for the radioactive discharge control including the development of practical guidance for setting discharge limits, the elaboration of a methodology for the radiation protection of non-human species, and the preparation of guidance on environmental modeling and monitoring for radiation protection purposes. The development of the IAEA safety documents is influenced both by the new ICRP recommendations and feedback from practical experience of application of existing standards. Recent international and regional tendencies, to reduce radioactive discharges below levels justified by radiological criteria are discussed.

Alpha spectrometry is the most commonly used analytical tool for the determination of Pu, Am, Pa, U and Th long live radionuclides. Thermal ionization mass spectrometry (TIMS) and acceleration mass spectrometry (AMS) are also still considered as primary methods for the determination of their isotope ratios. Spectrometers with plasma ion sources now offer another efficient alternative method with the development of sector field inductively coupled plasma mass spectrometry (SF ICP-MS). This paper summarizes the development work performed and results obtained using this technique for the analysis of such radionuclides. Isotopic ratios and ultra trace levels of man made radionuclides like 239, 240, 241 plutonium but also naturally occurring species like 231 protactinium, 234, 235, 238 uranium and 230, 232 thorium were determined in different field samples and reference materials using a micro concentric nebulizer as an introduction system for the mass spectrometer. Prior to the mass spectrometric measurements these elements were isolated from major elements by different selective precipitations. In further steps, they were purified by anion exchange. Results of isotope ratios including plutonium ones are also discussed.

In the frame of IRSN's French radioactivity observatory, aerosol samples are collected in a ten-days basis in different locations and measured by gamma spectrometry. For some studies, it is necessary to have the average of a radionuclide in aerosol samples, i.e. monthly or annually. Gamma spectrometry measurement of artificial radionuclides such as 137Cs is becoming more difficult due to decreasing radioactivity levels. Individual measurements are sometimes below the minimum detectable activity (MDA) even when low-background measurement procedures are used. In these cases, how can a MDA in an average computation be taken into account? In order to acquire this mean value, the analysis can be performed on the annual spectrum corresponding to a running sum of each individual spectrum. As for the sample, the summing is applied for the background spectrum. In this way, the 137Cs concentration in aerosols corresponding to the annual mean value is obtained. For aerosols collected in La Reunion, a mean concentration of $0.029 \pm 0.010 \mathrm{\mu}$Bq.$\textrm{m}^{-3}$ for 137Cs is obtained, when 25 measurement results on 26 samples are below the MDA. For radionuclides always detected, a good agreement between summing spectrum results and computed mean value is observed.

Uranium ore tailings and radioactive waste have been stored during four decades at the Mexican Storage Centre for Radioactive Waste (SCRW). An estimation of effective doses from sources of natural and artificial origin in the general population and workers is presented. The sampling points are located at the SCRW at a 200 m neighbouring zone of the site and at distant communities around SCRW (regional background). The effective gamma dose rates were estimated from measurements of radionuclide concentration in soil samples from 1991 to 2002. Doses from the outdoor and indoor inhalation of radon were also determined. Transfer factors for 226Ra, 210Pb, 137Cs and 40K from soil to wild edible species have been used to estimate the contribution of wild local foods to the dietary intake and to assess the supplementary doses received due to internal irradiation. The effective dose via the different exposure pathways estimated in the population that would live at the future in the immediate SCRW vicinity was two times higher than for the regional background.

Terrestrial contamination by 137Cs and 134 Cs since 1986 in France is held to originate in atmospheric nuclear weapon tests and/or the releases from the Chernobyl accident. Monthly measurements of radioactivity in terrestrial mosses are part of the monitoring protocol carried out by the Conseil Général of Tarn-et-Garonne to assess the environmental impact of the Golfech nuclear power plant radioactive releases. Since the commissioning of the NPP in 1990, these monthly measurements revealed a contamination by 137Cs and 134Cs (up to 700 and 60 BqKg-1 DW) in both sampling sites. This contamination decreased by a factor about 10 over 1990-2004 through three stages (134Cs undetectable since 1995). It is significantly correlated over large periods of time with the monthly levels of atmospheric halogens-aerosols releases by the Golfech NPP (95%, r2 = 0.35 to >0.84). These results are discussed in the light of the time since radioactive releases, of the operating and release conditions of/from the Golfech NPP and of the mosses sampled. These preliminary results bear evidence of an impact of the Golfech NPP on the terrestrial environment. They confirm that species of terrestrial mosses are particularly sensitive to low levels of atmospheric radioactive caesium contamination and are a good indicator of a radioactive fallout. They suggest that terrestrial mosses may serve to elaborate a predictive model of a caesium release, together with some relevant parameters and in the framework of a carefully defined monitoring protocol.

Scales and sludge are commonly formed during oil and gas extracting and processing operations. They usually appear when injection and formation water with different chemical characteristics come into contact. When the produced water is brought to the surface alongside with the oil, a precipitate can be deposited on the walls of pipes and equipment, forming the so-called scales. Otherwise they can accumulate in the form of sludge on the bottom of storage tanks, separators, and other equipment. Radium is the main radionuclide brought to the surface with oil and produced water and it co-precipitates with barium forming complex compounds of sulfates, carbonates and silicates. These compounds are the main constituents of scale and sludge. The objective of this work was to relate the radium content of scales and sludge to their chemical and mineralogical composition. Samples were taken from a PETROBRAS Unit in the State of Sergipe, in Northeast Brazil. They were collected either from the inner surface of water pipes or from containers in the waste storage area of the Unit. Oil was separated from the solid material in a Soxhlet extractor equipment by using aguarras as solvent. The concentrations of 226Ra and 228Ra were determined by gamma spectrometry. Both the mineralogical and chemical composition of samples were determined by X-ray diffraction and X-ray fluorescence, respectively, and used to characterize samples as scales or sludge. The results showed that scales are mainly formed by BaSO4 and CaCO3 while sludge composition is quite variable, having higher contents of SiO2 and FeO3 than those observed on scale samples. The measured activity concentrations of 226Ra and 228Ra are strongly correlated for both kinds of samples.

The pilot operation of the nuclear power plant (NPP) Temelín first block was started up in 2001 and of the second block in 2002. Since 1990, the systematic attention has been paid to the monitoring of the hydrosphere reference level in the NPP Temelín vicinity. The Temelín NPP waste water influence has been monitored and assessed since 2001. The monitoring has been focused especially on the tritium, strontium-90 and caesium-137 concentration changes in water, river bottom sediments, fish, and in the water plants biomass. The observed half-lives indicate that the strontium-90 and caesium-137 releases fully interfere with the residual contamination after the nuclear weapons tests and the Chernobyl accident in the last century. Only the tritium concentrations in water samples, taken in the Vltava River downstream from the NPP Temelín waste water outflow, show a measurable influence.

The results of an environmental survey of tritium in the vicinity of Creys-Malville nuclear plant are presented. The plant, which was shut down in 1998, is currently in its initial stage of dismantling. Measurements in the terrestrial environment do not provide any indication that tritium levels are significantly above the regional background. Tritium concentrations in groundwaters and in the river Rhône waters are at their background level too, with values in the range 0.94-1.64 Bq/l. In contrast, the various aquatic compartments of the river (fishes, plants, sediments) show enriched non-exchangeable bound tritium concentrations both upstream and downstream of the power plant, with values up to 14.7, 49 and 1495 Bq/kg (dry weight) respectively. Although fine particles of tritiated compounds entering in the composition of luminous paints have been suspected on several occasions, the nature and the origin of this tritium source, which is not related to the nuclear plant, remain unknown and will require further investigations.

The TOCATTA model simulates 14C transfer within terrestrial and/or continental water ecosystems, in response to chronic and accidental hypothetical emissions of 14C, in a liquid and/or gaseous form. This model has been developed from bibliographical knowledge on C cycling and common hypothesis to existing 14C transfer models, in order to come within the conceptual and mathematical frameworks of the SYMBIOSE project. In this context, the conceptual modelling deals with discretizing the continental biosphere into elementary components likely to be contaminated and identifying interactions or transfer processes of 14C between two components. The mathematical modelling for calculating stocks and fluxes under accidental conditions is based on a system of differential equations expressing conservation of pollutant activity for each component of the conceptual model. It is shown that the analytical solutions obtained when temporal derivatives of the differential equation system are equal to zero correspond to the activities at “steady-state" simulated for chronic contaminations.

Tritium concentrations of groundwater samples from the Environmental Monitoring Program at IPEN (Institute of Nuclear and Energetic Researches), São Paulo, Brazil, covering the years 2000 to 2003, were determined by liquid scintillation counting and the results laid in the range of 20 Bq$\cdot$L-1 to 91 Bq$\cdot$L-1. The effective committed dose for general public considering the highest concentration value is 1.3 μSv$\cdot$y-1, which is below the ICRP dose limit of 1mSv$\cdot$y-1. Tritium concentration of radioactive liquid effluents samples from the IEA-R1 research reactor storage tank showed values from 3.6×103 Bq$\cdot$L-1 to 6.2×103 Bq$\cdot$L-1, approximately 1000 times below the Brazilian daily discharge limit of 3.7×106 Bq$\cdot$L-1.

The consequences for the man and the environment of the discharges of nuclear facilities depend on the importance and the nature of the discharges, but also on the environment which receives them. Thus, the impact of a pollution, which is expressed in term of toxicity, risk or economic consequences, varies according to the characteristics of the environment and the use of this environment by the man. The radioecological sensitivity can be defined as the response of the environment to a radioactive pollution. For a determined discharge, the higher is the response, the more sensitive is the environment. If all the ecosystems appear sensitive, their sensitivity does not concern the same criteria and it is currently difficult to compare these criteria between them. The idea of the SENSIB project is to create a standardized tool which makes it possible to represent and to compare with the same scale the sensitivity of various ecosystems. The SENSIB project aims to develop both a methodology to calculate sensitivity indexes and a radioecological sensitivity scale usable for risk management.

The aim of the study was to measure the carbon 14 activity at natural level in air samples using classical methods of radiochemistry and beta counting. Three different methods have been tested in order to minimise the detection limit. In the three methods, the first step consists in trapping the atmospheric carbon 14 into NaOH (1N) using a bubbling chamber. The atmospheric carbon dioxide reacts with NaOH to form Na2CO3. In the first method the Na2CO3 solution is mixed with a liquid scintillate and is directly analysed by liquid scintillation counting (LSC). The detection limit is approximately 0.3 Bq.m-3 of air samples. The second method consists in evaporating the carbonate solution and then counting the solid residue with a proportional gas circulation counter. The detection limit obtained is equivalent to the first method (0.36 Bq.m-3 of air samples). In the third method, Na2CO3 is precipitated into CaCO3 in presence of CaCl2. CaCO3 is then analysed by LSC. This method appears to be the most appropriate, the detection limit is 0.04 Bq.m-3 of air samples.

The present study is the second part of a program of characterization of the site surrounding the SoGIN Garigliano Nuclear Power Plant (Southern Italy), which is currently involved in decommissioning activities. In the first phase of the project the reference groups of the population were established on the basis of a socio-economical study of the site; the radiological doses due to the assumed radioactive releases during the decommissioning phase were calculated by using climatological, hydrological, geomorphological parameters of the studied area; transport and diffusion specific models of some radionuclides in the environment were implemented to calculate the dose using specific evaluation software. The second part of the study focuses on the project of an environmental network designed in order to ensure the continuous monitoring of the radioactive release concentrations. All the criteria for the choice of grid points, by considering specific paths of transfer in the environment, were established for all the environmental compartments. A field campaign was carried out aiming to assess the “zero level" due to the natural radioactivity and past anthropogenic activities.

In France, the mining and milling of uranium ore and the disposal of uranium mill tailings involved nearly 200 sites of very different nature. Being in charge of both the review of some remediation reports and the routine monitoring of the environment provides IRSN with selective data on most sites. The data collected by IRSN as well as those available from other data sources often remain incomplete therefore preventing IRSN from presenting a global view or answering some specific questions. In order to overcome this difficulty, it was decided, under the aegis of the Ministry of Ecology and Sustainable Development, that IRSN should develop a program of investigations organized in two parts: Part 1, called “State of knowledge" is aimed at assessing the amount of information available and at consolidating it into a user-friendly computerized database. The main goal is to identify the occurrence of significant enhanced radiological levels in the environment and to detect any lack of information concerning the various sites. This paper gives an overview of the information already collected. Part 2, called “specific studies" is aimed at fixing the gaps in the database by implementing new investigations on specific sites. It could lead to improvements in networks for the monitoring of radioactivity in the environment.

In this contribution, the results of the radioactivity bio-monitoring of the Vltava River before (1996-2000) and after (2000-2003) the start-up of the PWR-type South Bohemian nuclear power plant are presented. The liquid radioactive effluents are discharged into the Vltava River, which also serves as a source of drinking water intended for Prague. The bio-monitoring was made by means of water plants and freshwater bivalve that are found along the watercourse. Biological samples were processed and then the activity of natural and man-made radionuclides was assessed by gamma-spectrometry. The analysed statistical data did not prove any impact of the three years NPP operation on the Vltava River radioactivity.

There is much current interest in managing and manipulating radionuclide transfer from soils to plants, either for `safe' crops or for phytoextraction of radionuclide contaminated soils. Potentially there is biodiversity in plant uptake that might aid these efforts. We have established the effects of phylogeny (evolutionary history) on the uptake of numerous heavy metal and nutrient elements. Here, using the same Residual Maximum Likelihood techniques, we report phylogenetic effects on radionuclide uptake by plants derived from databases of several hundred species of plants we have collated over recent years. There are differences of at least two orders of magnitude in the concentration to which plants take up isotopes of Cs, Sr, Cl, Ru, S, and I. When analysed using hierarchical Analysis of Variance coded using a recent molecular phylogeny of flowering plants it is clear that for no radionuclide is all the variation inter-specific. Rather, for all radionuclides some of the inter-taxa variation is associated with higher taxonomic levels. In general, therefore, groups of plants with high and low uptake of radionuclides, and that might be useful for managing or manipulating radionuclide uptake, can be delineated. Here we discuss some of these groups and how they might be useful.