With the development of nuclear power programme, an additional consideration outside the existing radiation protection framework appeared: the need to assess not only the level of exposure, but also to take into consideration the accidents which could release large inventories of radioactivity. With the expansion of nuclear commitments, the inventories of Tritium are bound to increase. The possible use of tritium as the fuel for fusion reactors in the near future may result in an additional source of tritium. Swiss albino mice of 1, 2, 3, 4 & 6 weeks of age were injected with tritiated water (HTO) at the dose 111 kBq/gram body weight and the animals from each age group autopsied on 1, 7 and 30 days post- injection. The mouse show radiovulnerability with a capability to repair and recover from the rendered damage during the first half (1 week to 3 week) of postnatal development, whereas during the second half (4 week to 6 week of age) a tendency towards radioresistance is achieved. The presentation is an attempt to revisit the behaviour of tritium with its possible implications on the environment in accordance with the presently projected radiation protection framework.

In 1986–2009 the dynamics of the radionuclide contamination of the Pripyat inlet ánd Perstok Lake and their biota as well as the set of biological test criteria reflecting impact of ionizing radiation on pulmonate mollusk Lymnaea stagnalis from these reservoirs have been investigated. The γ-activity of biota after the highest level in 1987 (up to 1100 kBq kg−1 wet mass) quickly decreasing. In 2005–2008 the activities of biota in the Pripyat inlet dropped to the natural level, but in the Perstok Lake they remained a rather high – up to 4000 Bq kg−1. Alongside the increase of activity of transuranium α-isotope 241Ám in bottom sediments of the Perstok Lake has been observed since 2006. In the L. stagnalis population in the Perstok Lake the obvious negative effect of chronic impact of radiation was noted. The share of cells with the micronuclei has considerably grown there if compared with the mollusks from the Pripyat inlet. The negative effects mentioned above did not influenced seriously on the viability on organism and populations levels. So, the embryonic mortality in both populations is low and they are capable to maintain sufficient level of reproduction despite the chronic radioactive impact.

This study aimed at investigating biological effects in Arabidopsis thalianaleaves and roots irradiated for 72 h with 3.5 Gy or 30 Gy of gamma radiation, and to unravel oxidative stress related responses to achieve a better understanding of the importance of the cellular redox balance as a modulator in gamma radiation stress. A. thaliana performs like a rather radioresistant plant species as no alterations on growth and only minor alterations in the nutrient profile were observed. Gamma irradiation did not seem to induce an NADPH mediated oxidative burst and lipid peroxidation appeared to be directly induced by ionizing radiation rather than mediated through LOX activity. As ionizing radiation can cause indirect damage via water radiolysis, H2O2 is hypothesized to be an important reactive oxygen species under radiation stress. Although most H2O2-scavenging enzymes remained unchanged, important alterations were observed for CAT1, CAT2 and CAT3expression.

The LLW Repository Limited has recognised the potential importance of the processes being considered in the BIOPROTA 14C working group and funded the development a new 14C model that addresses the exchange of gas in a soil-plant-atmosphere system. This model considers two regions in the above-ground atmosphere and utilises concepts from the field of micrometeorology to describe the exchange of air between these regions and losses from the area of interest. The lower layer only experiences molecular diffusion processes in relation to the movement of molecules of CO2, whereas the upper layer experiences some degree of turbulent mixing as a result of winds which flow over the area of interest. The thicknesses of these layers depend upon the canopy density, which will affect the light intensity and thus the rate of photosynthetic uptake of carbon in the canopy profile. Model results demonstrate the impacts of 14C-labelled gas from the soil upon the calculated 14C concentration in plants for a variety of plant species (pasture and garden crops) and subsequent doses to human exposure groups. The technical modelling work described has been funded by the LLW Repository Ltd in support of its 2011 Environmental Safety Case.

To quantitatively evaluate OBT production after a nighttime wet deposition of atmospheric HTO onto land surface, numerical experiments using a sophisticated tritium transport model (SOLVEG-II) were conducted. For a nighttime rain actually observed at a grassland site, two hypothetical scenarios for wet deposition of HTO were made; 0.1-folded and 10-folded case, each having rain HTO concentration at 0.1 folds and 10 folds of equilibrium concentration of ground-level air HTO concentration. Calculation results showed atmospheric HTO concentration after the rain at 10-folded case was more than an order of magnitude larger than that at 0.1-folded case, affected by interception and evaporation of rain HTO with leaves, and, by a larger HTO re-emission from soil. After the rain, due to these heightened atmospheric HTO, TFWT concentration in leaf cellular water at 10-folded case kept an order, or more, larger than that at 0.1-folded case. As a result, OBT produced in leaves over nine-day after the rain at 10-folded case was 18 times larger than that at 0.1-folded case. We therefore concluded that nighttime wet deposition of HTO pronouncedly increases OBT formation if rain HTO concentration exceeds equilibrium concentration for the air HTO near the ground.

The Institut de Radioprotection et de Sureté Nucléaire (IRSN) performed a series of air sampling campaigns at mesoscale distances (10–80 km) from the AREVA La Hague reprocessing plant (north west of France) between 2007 and 2009. These samples were collected in order to test and optimise a technique to measure low krypton-85 (85Kr) air concentrations, and to investigate the performance of three atmospheric dispersion models (RIMPUFF, HySplit, and ADMS). This paper presents 85Kr air concentrations measured at both land and sea locations. In addition, this paper compares the measured 85Kr air concentrations, which varied from 2 to 8000 Bq m−3, with the predictions from the atmospheric dispersion models. During stable wind conditions, the dispersion models make reasonable estimates of the 85Kr field measurements. In contrast, the models fail to accurately predict temporal peaks in concentration during periods of rapid and large changes in wind speed and/or wind direction.

Tritium can represent a key radionuclide in the aquatic environment, in some cases, contributing significantly to the doses received by aquatic non-human biota and by humans due to aquatic releases. Recently, the necessity to have a robust assessment of tritium routine and accidental risk emissions for large nuclear installations increased the interest in the topic. In the present study, the recent experiments concerning tritium transfer in adult rainbow trout are described. The updated model concerning the dynamics of tritium transfer in aquatic food chain (AQUATRIT model) developed by the authors is applied and tested for these experimental data. The model predicts the experimental data with a factor of 2 to 3 and the potential improvements of the model are discussed. The present model results emphasize that in the field conditions, the major factors influencing the OBT biological loss rate are the temperature and the prey availability while, the OBT uptake is mainly influenced by the fish growth rates. The main goals of this study are to enhance the robustness of aquatic models for tritium risk assessment and to fulfil a gap for aquatic pathways in environment.

Population of small rodents in radiocontaminated environment is compelled to include more energy-intensive way of maintenance its ability to live — increasing of the proportion of mature young of the year (first pathway of ontogeny). Their reproductive characteristics — actual fecundity was higher, whereas embryonic mortality and the proportion of females with embryonic losses were significantly lower compared with neighboring areas. Abundance of mice in the impact zone was higher, age cross was revealed, which improves the adaptive possibility of the population. Preconditions for acceleration of evolutionary transformations of a population are created, but this process is restrained by both the local configuration of the polluted territory and migration of murine rodents. As a consequence, the population decreases the probability that certain changes will be fixed and inherited in a series of generations. Chronic low-dose radiation (stress) can be considered as the mechanism of switching of life history of cyclomorphic mammals. Thus, ontogenetic multiversality of small mammals is an important mechanism of protection strategy of population and decreasing the damaging action on biota in radiocontaminated environment. Functional approach makes it possible to reduce errors in assessing the radiological consequences and hence, can provide a reliable methodological basis for organization of biological monitoring.

Tritium (3H) transfer into environment must be modelled differently than the transfer of other radionuclides released from nuclear reactors because hydrogen represents the building blocks of life. A solid understanding of 3H behaviour is essential because 3H may be released in large quantities from CANDU (CANada Deuterium Uranium) reactors and from future thermonuclear reactors. Recently, the authors published a complex dynamic metabolic model for 3H and 14C transfer in farm and wild animals, but the model applications for wild biota were restricted to too few examples and mostly for 14C transfer. In this study, the model is applied to few selected wild animals for 3H uptake. Despite the lack of any experimental data for wild animals, the results presented in this study are less uncertain than for many other radionuclides and can provide a useful estimation for biota radioprotection.

Planning for the disposal of spent nuclear fuel is at an advanced stage in several nations around the world. Licensing of the disposal facility requires correspondingly detailed assessment of the future performance of the facility. With increased site-specific detail available to the assessment, local characteristics play an increasingly important role in determining the potential radiological risk posed by releases to the biosphere. In this paper we go beyond existing reference biosphere models and investigate the potential for specific accumulation mechanisms. The implications for the modelling carried out in long timescale performance assessment are discussed.

The two-chamber (water and bottom sediments) model was used to analyze factors influencing magnitude of 137Cs accumulation factor in bottom sediments of rivers and lakes with concentration of the radionuclide close to background levels. The most probable values of the factor are given. It is proposed to use the factor for assessments of 137Cs activity in water on the base of its observed activity in bottom sediments.

Observations carried out in the frame of the ISTC project 3547 [1] were used to parametrize and validate the model of radionuclides transport from Siberian Chemical Combine (SCC) by the Tom and Ob rivers and also to assess discharges of radioactive substances from SCC to the Tom River and to estimate possible contamination of the rivers in case of accidents.

The aim of this study is to assess the interception and transfer to edible part of wet deposited 134Cs and 85Sr to spring oilseed rape and spring wheat and the dependency of the intercepted fraction on the development stage e.g. the total plant biomass. The radionuclides, 134Cs and 85Sr, were deposited at six different development stages using a rainfall simulator. The results showed that there was a positive correlation between the interception fraction for 134Cs and 85Sr and the biomass both for spring oilseed rape and spring wheat. The interception fraction and transfer factors were highest at growing stage of senescence (ripening) for both crops.

Long-term observations on the effects of a fertilization treatment on 137Cs concentrations in forest vegetation are scarce. Needles of Scots pine were used as biological indicators of radionuclide uptake of trees. The fertilization experiments are located in western Finland in an area where radioactive contamination from the Chernobyl accident in 1986 was relatively high (22–75 kBq m−2) compared to other parts of Finland. Fertilization treatments included different combinations of major nutrients, i.e. nitrogen, phosphorus, potassium and calcium. Needle 137Cs concentrations of Scots pine were analyzed during 1991–2006. The effect of fertilization on 137Cs concentration was tested 5 to 20 years after radioactive contamination from the Chernobyl accident in 1986. Fertilization clearly decreased 137Cs concentration in Scots pine needles 1–21 growing seasons after application. Single K fertilization decreased significantly 137Cs concentration 21 growing seasons after radioactive deposition on a drained mire. Mineral nutrients (application of commercial fertilizer or wood ash) can well be recommended for remediation of forests contaminated by accidental radionuclide deposition. The site conditions need to be taken into account in planning of remediation.

For appropriate safety assessment of TRU waste disposal, the dominant chemical species of 14C-gas was studied. [1,2-14C] sodium acetate was added to flooded paddy soil samples, and the content of 14C in the soil, solution, and the emitted CO2 gas during incubation period was determined. Recovery ratios of the total 14C activity to the initial 14C activity were 97.9% at day 1, 86.4% at day 3, and 83.5% at day 7 of incubation. The result of the day 1 means that the emitted 14C-gas was almost 14CO2. At day 7 of incubation, about 16.5% of 14C was failed to recover. Even if the unknown 14C was gases other than 14CO2, the dominant chemical species of the emitted 14C-gas will be 14CO2, because the recovery ratio of the 14CO2 was 48.9% (¿16.5%). Sodium 2-bromoethane-sulfonate was used to ensure the emission of CH4, but there was no effect of the regent to the recovery ratio of 14CO2. Methane emission may be little under our experimental conditions. These results suggest that the dominant chemical species of the emitted 14C-gas from the flooded paddy soil samples was 14CO2.

In this study it is shown how the behaviour of radionuclides in agricultural soils can be quantitatively estimated. The sorption of those nuclides onto soil particle surfaces is a key process which every predictive model has to take into account. This has been accomplished by implementing a component additivity (CA-) model into the well known geochemical code PHREEQC that includes the most important sorbents clay, amorphous iron oxide and organic matter. For uranium and cesium it is shown that model calculations are in excellent agreement with experimental data.

The toxicity and oxidative stress responses of 19-day old Arabidopsis seedlings induced by U (66 μM) and Cd (20 μM) alone or in a binary mixture set-up (equitoxic mixture) are studied in function of time. After 48h a significant decrease in root and shoot growth and a simultaneous increase in anthocyanin production was evident in all treated plants.

Production of O−2 or H2O2 was visualized by staining freshly harvested leaves with nitrobluetetrazolium or diaminobezidine, respectively. With this method production of O−2 was only significantly measurable after 168 h treatment which coincides with a significant decrease in biomass production and probably also plant cell death. For Cd treated plants a significant increase in H2O2 production was measurable from 24h onwards. In contrast, a similar H2O2 production could not be measured in U or U + Cd treated plants. Both water and lipophilic soluble antioxidants significantly increased in U treated plants after 48 h. These high antioxidant levels might detoxify potential H2O2 produced in the U treated plants. In contrast for Cd treated plants only after 168h a significant increase in water soluble antioxidants was measured whereas no difference in the lipophilic fraction was visible.

Adaptive responses were observed using the micronucleus frequency in bullfrog tadpoles. In tanks in which control tadpoles were placed in contact with tadpoles that were previously housed in tritiated water (3.0 × 104 Bq/L), the cells from all animals responded as though they were “adapted”. This suggests that direct exposure to 3.0 × 104 Bq/L tritium contributes to an increased resistance to a high dose of radiation in liver cells. It also suggests that being in contact with tadpoles that were previously exposed to 3.0 × 104 Bq/L tritium (bystander effect) contributes to an increased resistance to a high dose of radiation in liver cells.

In vitro exposures were also conducted using primary cultures of liver cells obtained from an unexposed-non-bystander tadpole. In these control cells, it was observed that exposure to 100 mGy of 60Co gamma radiation (delivered at a dose rate of 5 mGy/min) did not affect the micronucleus frequency whereas exposure to 4 Gy (delivered at a dose rate of about 10.2 Gy/min) increased the micronucleus frequency. Prior exposure to a low dose of 60Co gamma radiation (100 mGy delivered at a dose rate of 5 mGy/min) induced an adaptive response, protecting the cells from harm caused by exposure to subsequent high doses of 60Co gamma radiation (4 Gy delivered at a dose rate of about 10.2 Gy/min). Using the adaptive response (determined using micronucleus assay) as a biomarker, the data obtained suggest that bystander effects do play a role in wild populations since bullfrog tadpoles that were not exposed to tritium responded like the tadpoles that were directly exposed to tritium after being placed in contact with them.

The aim of the present work was to study the impact of chemical climate (i.e. the chemical composition of precipitation) on radioactive caesium in soil and plants. This was done through field studies and a laboratory experiment. Three types of precipitation regimes were considered in both cases, representing a natural range found in Norway: Acidic precipitation (southernmost part of the country); precipitation rich in marine cations (coastal areas); and low concentrations of sea salts (inland areas). Results indicate that acid rain increases the mobility and the plant availability of radioactive caesium.

The FASTer-lite model is multi-compartmental model that can be used to simulate transfer through a simple terrestrial food-chain. The model uses allometric relationships to describe dietary intake rates and radionuclide biological half-lives; the latter were mostly derived from published literature. This type of conventional modelling, for simulating the transfer of radionuclides to representative animals such as birds, results in the observation that activity concentrations associated with ecological compartments approach an equilibrium after a certain time interval. Whilst this approach has validity, however, it is not biologically plausible as it ignores reproduction. In this study we calculate how activity concentrations may vary if transfer to eggs and subsequent growth dilution occurring within juvenile birds is accounted for.