Sr In Water Research Articles

Modelling of the Fate of 137Cs and 90Sr in the Chornobyl Nuclear Power Plant Cooling Pond before and after the Water Level Drawdown

During the accident in April 1986, the Cooling Pond (CP) of the Chornobyl Nuclear Power Plant (ChNPP) was heavily contaminated by fuel particles and radionuclides of cesium-137 (137Cs) and strontium-90 (90Sr). Starting from the end of 2014, a gradual decrease of the CP water level began leading to the transformation of the whole reservoir into eight separate sectors and raising the concern of the fate of 137Cs and 90Sr in the future. In this study, two mathematical models were applied to reproduce radioactive contamination of the CP from 1986 to 2021 and to provide a forecast of 137Cs and 90Sr concentrations in the CP water from 2022 to 2030. The hydrodynamic model THREETOX provided three-dimensional (3D) currents in the CP corresponding to hydrological conditions before and after water level drawdown, and these currents were used in the box model POSEIDON-F for the long-term simulations of the changes in 137Cs and 90Sr concentrations in water, bottom sediments, and biota. Seasonal changes in the distribution coefficient (Kd) describing the partition of 137Cs between water and sediments were considered in the box model, which allowed us to reproduce the observed variations of concentration. Calculated concentrations of 137Cs and 90Sr in water and freshwater fish occupying different trophic levels agreed well with measurements for the entire post-accident period. After the water level drawdown, concentrations of 137Cs in the CP water slightly increased in all eight sectors, while 90Sr concentrations significantly increased in sectors close to ChNPP, which was explained by an additional 90Sr source when comparing the simulation results and measurement data. Using the model forecast from 2022 to 2030, we predict that the concentration of both radionuclides will gradually decrease in new water bodies of the Cooling Pond except in the northern sectors, where the suggested additional source of 90Sr will lead to a stabilization of 90Sr concentrations.

Reconstruction of the Contamination and Purification of White Sea Water to Remove Global 90Sr

Contamination with 90Sr of the White Sea water in migration during 50 years is reconstructed with the use of a three-component exponential model. Т1, Т2, and Т3, the periods of half-purification of White-Sea water to remove 90Sr were 0.8, 15.4, and 29 years, respectively. During 50 years of migration, the content of 90Sr in water decreased from 41 to 2–3 Bq/m3. The maximum decrease in the content of 90Sr was observed in 1965–1968. The outflow of 90Sr in 1970 from the White Sea was 37.5, and the inflow with Barents-Sea water, 25.5 TBq. The outflow was partly compensated for by the inflow of 4 TBq of 90Sr with water of the rivers Northern Dvina, Onega, Mezen’. The White Sea water is a weak source of 90Sr for the Barents Sea. The inflow of global 90Sr with the river flow makes slower the replacement of the more contaminated White Sea water with the purer water of the Barents Sea. The determinations of 90Sr in the White Sea water (1965–2015) in terms of the exponential model have been confirmed by the results of experimental observation of 90Sr in the sea bays. During 50 years, 1.5–2 times higher concentrations of 90Sr were preserved in the semi-closed White Sea, compared with the Barents Sea.

A rapid method for screening 90Sr activity in water and milk samples using Cherenkov radiation

Strontium-90 is one of the most dangerous fission products that enter the food chain. Because of its similar chemistry to calcium, it is deposited to bones posing a high risk for human health. 90Sr is a pure ^-emitter and decays to 90Y also a /3-emitter. The fast moving electrons emitted by the 90Y decay, produce Cherenkov radiation, which can be detected by a Liquid Scintillation Counter (LSC). Water and milk samples spiked with various concentrations of 9 0Sr/90Y in equilibrium were measured in a LSC (Tricarb 3170 TR/SL). The derived efficiencies were 50% for water samples and 13 % for milk samples. The minimum detectable activities (MDA) for measuring 90Sr in water and milk samples, without any pretreatment were calculated 240 mBq/L and 1 Bq/L respectively. The intervention levels for 90Sr contamination in water and milk samples, established by the European Union are 125 Bq/L and 75-125 Bq/L depending on age, respectively. The interference of 40K, which is present in milk due to its natural potassium content,was also investigated.

Sources of inflow and nature of redistribution of 90Sr in the salt lakes of the Crimea

At the first time for the period after the Chernobyl NPP accident the nature of the redistribution of the 90Sr concentrations in components of the ecosystems of the salt lakes of the Crimea were identified and described. Concentration of 90Sr in water of the salt lakes depends on the sources of the inflow this radionuclide into aquatic ecosystems and salinity level of lakes water. Until April 2014 the flow of the Dnieper river water through the Northern-Crimean canal was more important factor of contamination of salt lakes of the Crimea by 90Sr, than atmospheric fallout of this radionuclide after the Chernobyl NPP accident. Concentrations of 90Sr in water of the salt lakes of the Crimea exceeded 2.4–156.5 times its concentrations in their bottom sediments. The 90Sr dose commitments to hydrophytes, which were sampled from the salt lakes of the Crimea have not reached values which could impact them during entire the after-accident period.

Radiation-ecological and toxicological characterization of the Uzh river water

The hydrosphere is one of the main tanks, which eventually received artificial radionuclides produced in nuclear explosions and in the operation of nuclear power plants. When accidents at nuclear power plants, in particular the Chernobyl large contribution to the total emissions of radioactivity have long-lived radionuclides — 90Sr and 137Cs. Sources of contamination of river water after the accident were like immediate loss of aerosols on the water surface, and radionuclide contaminated surface water runoff from the watershed and soil particles during the rainy or melting snow, a local radionuclide contaminated tributaries waters that it led to their entry into the rivers and the transfer to the water streams down to the Black Sea. Migration of the latter in the aquatic environment is considered in this article. We determined the concentration of artificial radionuclides in the waters of the river Uzh on the territory of Kiev region and their danger to fish fauna. It has been found that 137Cs and 90Sr in water are mainly in the form of solution. Also, the vast amount of radionuclides in the ecosystem is situated in bottom sediments. As a result of the Chernobyl accident radionuclide contamination of aquatic ecosystems has become a permanent factor of influence on the life of aquatic organisms. Comparison of 90Sr and 137Cs in fish with different types of food shows that ichthyophagi contained more radionuclides than planktonofagi. Pit-trap polluted sludge played a significant role for water purification process from radionuclides.

Визначення активності 90Sr у воді шляхом прямого вимірювання рідинно-сцинтиляційним лічильником

Визначення активності 90Sr у воді шляхом прямого вимірювання рідинно-сцинтиляційним лічильником

Preparation of water samples for proficiency testing on radionuclides

The Institute of Nuclear Chemistry and Technology (INCT) procedure for preparation of water samples for proficiency testing on determination of 241Am, 137Cs, 239Pu, 226Ra and 90Sr in water is presented. Natural waters were applied as the raw materials and spiked with the aforementioned radionuclides. The procedure of spiking water allows to prevent losses of the radionuclides and to assign property values from formulation. The main advantages of this procedure are (i) similarity of the test materials to the water samples routinely analysed by radioanalytical laboratories, and (ii) traceable assigned values with low uncertainties.

Dispersion and fate of 90Sr in the Northwestern Pacific and adjacent seas: Global fallout and the Fukushima Dai-ichi accident

The 3D compartment model POSEIDON-R was applied to the Northwestern Pacific and adjacent seas to simulate the transport and fate of 90Sr in the period 1945–2010 and to perform a radiological assessment on the releases of 90Sr due to the Fukushima Dai-ichi nuclear accident for the period 2011–2040. The contamination due to runoff of 90Sr from terrestrial surfaces was taken into account using a generic predictive model. A dynamical food-chain model describes the transfer of 90Sr to phytoplankton, zooplankton, molluscs, crustaceans, piscivorous and non-piscivorous fishes. Results of the simulations were compared with observation data on 90Sr for the period 1955–2010 and the budget of 90Sr activity was estimated. It was found that in the East China Sea and Yellow Sea the riverine influx was 1.5% of the ocean influx and it was important only locally. Calculated concentrations of 90Sr in water, bottom sediment and marine organisms before and after the Fukushima Dai-ichi accident are in good agreement with available experimental measurements. The concentration of 90Sr in seawater would return to the background levels within one year after leakages were stopped. The model predicts that the concentration of 90Sr in fish after the Fukushima Dai-ichi accident shall return to the background concentrations only 2years later due to the delay of the transfer throughout the food web and specific accumulation of 90Sr. The contribution of 90Sr to the maximal dose rate due to the FDNPP accident was three orders of magnitude less than that due to 137Cs, and thus well below the maximum effective dose limits for the public.

Detection efficiency of plastic scintillator for gaseous tritium sampling and measurement system

To develop a gaseous tritium sampling and measurement system detection efficiency of plastic scintillator was examined. The advantage of using the plastic scintillator would be not expected to produce waste of liquid scintillator. Following the process of catalytic oxidization in the tritiated gas sampling system, a combined nebulizer and denuder tube was considered instead of a moisture absorber. The scintillation produced by exposure beta particle of tritium in the recovered water to the plastic scintillator was detected with a photomultiplier tube. The sensitivity to measure the tritium concentration in water was experimentally obtained. Then good linear relationships between the count rate and radioactivity were observed. Also the sensitivity to tritium and high-energy beta decay nuclides such as 14C and 90Sr in water were compared. The detection efficiency depended on the range of beta particle and the surface area of the plastic scintillator attached to the solution. Improving the effective surface area of the plastic scintillator would lead to a useful monitor.

Radioecological problems of aquatic ecosystems of the chernobyl exclusion zone

The dynamics of the main contaminating radionuclides in the components of aquatic ecosystems within the Chernobyl APP exclusion zone is considered. The possible causes are analyzed for the marked increase in the specific activity of 90Sr in water and hydrobionts of the lakes at the dammed left bank of river Pripyat. Notable is the elevated frequency of chromosomal aberrations in the root meristems of aquatic higher plants (up to 17%) and in the embryonal tissues of gastropod mollusks (up to 27%), alterations in the hematological indices for gastropods, and high infestation of aquatic higher plants by parasitic fungi and gall arthropods in the most radiocontaminated reservoirs.

Radioactivity in the Baltic Sea: inventories and temporal trends of 137Cs and 90Sr in water and sediments

The Baltic Sea is ecologically unique as one of the world's largest brackish water basins. It was signifi- cantly contaminated by radioactivity following the Cher- nobyl accident in 1986, the major contaminant being long- lived 137 Cs. Due to the slow exchange of water between the Baltic Sea and the North Sea and the relatively rapid sed- imentation rates, radionuclides have prolonged residence times in the Baltic Sea. 137 Cs levels are consequently still clearly higher than in other water bodies around the world. In addition to the Chernobyl accident, artificial radionuc- lides in the Baltic Sea originate from the global fallout following nuclear weapons testing in the 1950s and 1960s, while discharges into the Baltic Sea from nuclear power plants and other facilities are of minor importance. Here, inventories and the temporal evolution of radionuclides both in seawater and sediments of the Baltic Sea are pre- sented and discussed.

A rapid method for determining 89Sr and 90Sr by Cerenkov counting

A new combination of simple preparation techniques for determining 89Sr and 90Sr in water and milk samples using alginate has been developed and tested. By means of Cerenkov counting without a long ingrowth period for 90Y, results can be obtained within 4 days. The detection limit is about 1 Bq/l for a sample volume of 0.2 l. Milk samples can be prepared without ashing. A Liquid Scintillation Counter TRI-Carb 3170TR/SL in low-level mode has been used for counting.

Model testing of radioactive contamination by 90Sr, 137Cs and 239,240Pu of water and bottom sediments in the Techa River (Southern Urals, Russia)

This paper presents results of testing models for the radioactive contamination of river water and bottom sediments by 90Sr, 137Cs and 239,240Pu. The scenario for the model testing was based on data from the Techa River (Southern Urals, Russia), which was contaminated as a result of discharges of liquid radioactive waste into the river. The endpoints of the scenario were model predictions of the activity concentrations of 90Sr, 137Cs and 239,240Pu in water and bottom sediments along the Techa River in 1996. Calculations for the Techa scenario were performed by six participant teams from France (model CASTEAUR), Italy (model MARTE), Russia (models TRANSFER-2, CASSANDRA, GIDRO-W) and Ukraine (model RIVTOX), all using different models. As a whole, the radionuclide predictions for 90Sr in water for all considered models, 137Cs for MARTE and TRANSFER-2, and 239,240Pu for TRANSFER-2 and CASSANDRA can be considered sufficiently reliable, whereas the prediction for sediments should be considered cautiously. At the same time the CASTEAUR and RIVTOX models estimate the activity concentrations of 137Cs and 239,240Pu in water more reliably than in bottom sediments. The models MARTE ( 239,240Pu) and CASSANDRA ( 137Cs) evaluated the activity concentrations of radionuclides in sediments with about the same agreement with observations as for water. For 90Sr and 137Cs the agreement between empirical data and model predictions was good, but not for all the observations of 239,240Pu in the river water-bottom sediment system. The modelling of 239,240Pu distribution proved difficult because, in contrast to 137Cs and 90Sr, most of models have not been previously tested or validated for plutonium.

Metadata on the radioactive contamination of environmental objects on the territories of Russia and the USSR

A unique data archive, accumulated at the Taifun Scientific and Industrial Association in 1954–2005, on the radioactive contamination of the environment on the territory of the USSR and Russia is presented. The archive contains data on the yearly total β activity of atmospheric fallout on the underlying surface, the total volume β activity in the atmosphere at the ground, the results of measurements of the 90Sr and 137Cs content in samples combined over one month or quarter, atmospheric aerosols and fallout on individual points, the volume activity of tritium and 90Sr in water, rivers, lakes and seas, and the radionuclide contamination density of the territories of populated points as a result of the Chernobyl accident.

Scintillation material for determination of radionuclides in water

This paper is devoted to the development and use in radiation monitoring of new sorption materials, together with methods of their application for selective determination of radionuclide 90Sr in water. The material comprises a matrix, which is transacted by pores. A selective sorbent is fixed onto the surface of these pores. The material structure allows the passage of the liquid to be analyzed through the pores. The element to be determined is accumulated in the scintillator volume. Preconcentration of 90Sr inside a scintillation composite material, rather than through sample manipulation (evaporation, etc.), will greatly simplify the analytical process. 4π-Geometry is ensured for radiation detection, and simultaneously the radiochemical problem of radionuclide concentration is solved. Crystals of p-terphenyl doped with diphenylbutadiene were used as the matrix, and synthetic hydroxylapatite as selective complex-forming agent. The proposed method based on using porous scintillators allows detecting concentrations of 90Sr in the potable water, which are less than the maximum acceptable concentration (i.e. 2 Bq/l).

Plutonium, 241Am, 90Sr, and 137Cs concentrations in some Antarctic matrices.

A radioecological survey in Antarctica shows that the 239 + 240Pu, 238Pu, 241Am, 90Sr, and 137Cs activities were detectable in nearly all the samples. The activity level of 239 + 240Pu, 241Am, and 137Cs in antarctic sediments was about 5-20 times lower than in the northern Adriatic Sea sediments, but the 238Pu activities were relatively high. It was interesting to note that the 90Sr concentrations in all the sediments tended to be low, which could be the result of the easier exchangeable behavior of 90Sr in water. High concentrations were detected in mosses and lichens and their activity levels were comparable to those in central Italy. The radionuclide ratio analyses show that the major part of 239 + 240Pu, 241Am, 90Sr, and 137Cs was a result of nuclear weapon tests. The higher 241Am/239 + 240Pu ratio was observed and it could perhaps be the result of fallout of nuclear weapon tests prior to 1962. The 238Pu/239 + 240Pu ratio in the antarctic matrices was about seven times higher than in the Northern hemisphere and it could be inferred that the major part of 238Pu was originating from the SNAP-9A satellite accident.

137Cs and 90Sr in water and suspended particulate matter of the Dnieper River-Reservoirs System (Ukraine)

Fallout from the Chernobyl accident caused extensive contamination in the drainage basin of the Dnieper cascade (Ukraine). From 1986, a radiological monitoring system has been established along the Dnieper system of reservoirs. Samples of water were regularly collected in the rivers feeding the Kiev reservoir and in the inflows and outflows of the six large artificial reservoirs (Kiev, Kanev, Kremenchug, Dniprodzerdzin, Zaporozhie, Kakhovka) composing the Dnieper cascade system. Measurements of radiocaesium and radiostrontium made from 1987 to 1993 showed that the radioactive contamination of the rivers is considerably influenced by the hydrological conditions. As expected, the data revealed a close relationship between 90Sr concentration in water and river flow levels. 137Cs appears to be less dependent on surface hydrology. The reservoirs were found to act as sinks for radiocaesium with extensive accumulation recorded in the first reservoir. About 43% of the dissolved form of 90Sr that entered the Dnieper system from 1987 to 1993, reached the Black Sea.

Determination of strontium-90 in water and urine samples using ion chromatography.

A semi-automated method was developed for the determination of 90Sr in water and urine samples using ion chromatography. Yttrium-90 in secular equilibrium with 90Sr was initially extracted from the sample solution buffered to pH 5 using a high-capacity iminodiacetate chelating resin. At this pH, transition metals, lanthanides and actinides were extracted by the resin. The extracted metals were then transferred on to a separator column where they were separated and eluted as weak acid anionic complexes. The transition metals were eluted first by using a pyridine-2,6-dicarboxylate eluent, then the lanthanides, actinides and 90Y were eluted from the column by using an oxalate-diglycolate eluent. The fraction containing 90Y was then collected and beta-counted. For water samples, a minimum of sample preparation was required prior to chromatography, whereas an oxalate coprecipitation was included as a preconcentration step for urine samples. The derived recoveries for 90Sr for surface water, rain water and urine samples were 91.7 +/- 1.8, 91.9 +/- 1.6 and 90.0 +/- 2.7%, respectively, and the minimum detectable activity using gas flow proportional counting was 8 mBq.