Chernobyl radioactivity persists in reindeer

Title: Chernobyl radioactivity persists in reindeer

Author: Lavrans Skuterud, Eldar Gaare, Inger Margrethe Eikelmann, Knut Hove, Eiliv Steinnes

Reference: Journal of Environmental Radioactivity, Volume 83, Issue 2, 2005, Pages 231-252

DOI: http://dx.doi.org/10.1016/j.jenvrad.2005.04.008

Keywords: Caesium-137; Effective half-life; Reindeer; Lichen; Plant; Food chain; Chernobyl

Abstract: Transfer of ¹³⁷Cs in the soil–plant/lichen–reindeer food chain was studied in central (Østre Namdal) and southern Norway (Vågå) during 2000–2003. Reindeer from these areas have been continuously subjected to countermeasure application since the 1986 Chernobyl accident. In both areas no decline in ¹³⁷Cs concentrations was detectable in reindeer slaughtered in autumn since 1995, or in reindeer slaughtered in winter since 1998–1999. Seasonal differences in ¹³⁷Cs concentrations in reindeer have been less pronounced in recent years, with ¹³⁷Cs concentrations occasionally higher in autumn than in winter. Soil-to-plant ¹³⁷Cs transfer was significantly higher in Østre Namdal than in Vågå. Climatic influences on lichen growth and abundance, and on soil properties that influence the availability of ¹³⁷Cs for plant uptake, are hypothesized to have a larger impact on long-term transfer of radiocaesium in the soil–plant/lichen–reindeer food chain than has been previously observed.

URL: http://www.sciencedirect.com/science/article/pii/S0265931X05001402

90Sr migration to the geo-sphere from a waste burial in the Chernobyl exclusion zone

Title: 90Sr migration to the geo-sphere from a waste burial in the Chernobyl exclusion zone

Author: L Dewiere, D Bugai, C Grenier, V Kashparov, N Ahamdach

Reference: Journal of Environmental Radioactivity, Volume 74, Issues 1–3, 2004, Pages 139-150

DOI: http://dx.doi.org/10.1016/j.jenvrad.2004.01.019

Keywords: Chernobyl; Strontium-90; Fuel particles; Groundwater; Retardation; Sorption; Hydro-dispersion

Abstract: Results are presented from an ongoing field-scale experimental study (namely the Chernobyl Pilot Site project) aimed at characterization of processes controlling ⁹⁰Sr releases from a shallow trench containing nuclear fuel particles, and subsequent radionuclide transport in the underlying sandy aquifer at the Chernobyl nuclear power plant site. Microscopic analyses of waste material and leaching experiments have shown that 10–30% of the radioactive inventory is associated with chemically extra-stable Zr–U–O particles. The largest fraction of ⁹⁰Sr activity in the trench (≈30–60%) is currently associated with relatively slowly dissolving non-oxidized UO₂ matrix fuel particles. The ⁹⁰Sr migration velocity in the eolian sand aquifer is retarded by sorption to ≈9% of groundwater flow velocity (K_d ≈ 2 ml/g). The dispersivity values for non-reactive solute transport in the aquifer predicted by geostatistics (i.e. 0.8 6 cm) were confirmed by a natural gradient tracer test using ³⁶Cl. The observed negative correlation between hydraulic conductivity and K_d of aquifer sediments suggests that ⁹⁰Sr could be subjected to larger dispersion in the subsurface compared with ³⁶Cl.

URL: http://www.sciencedirect.com/science/article/pii/S0265931X04000244

Accumulation of Chernobyl-derived 137Cs in bottom sediments of some Finnish lakes

Title: Accumulation of Chernobyl-derived 137Cs in bottom sediments of some Finnish lakes

Author: Erkki Ilus, Ritva Saxén

Reference: Journal of Environmental Radioactivity, Volume 82, Issue 2, 2005, Pages 199-221

DOI: http://dx.doi.org/10.1016/j.jenvrad.2005.01.008

Keywords: Lake sediments; Chernobyl fallout; Caesium-137; Sedimentation rate

Abstract: The amount and vertical distribution of Chernobyl-derived ¹³⁷Cs in the bottom sediments of some Finnish lakes were studied. Sediment and surface water samples were taken in 2000 and 2003 from 12 stations in nine lakes and the results were compared with those obtained in corresponding surveys carried out in 1969, 1978, 1988 and 1990. Each of the five deposition categories of Chernobyl fallout in Finland were represented. The depth profiles of ¹³⁷Cs in the sediments showed considerable variety in the lakes studied. The peak values varied between 1.5 and 46 kBq kg⁻¹ dry wt. The size and shape of the peak did not always correlate with the amount of deposition in the area, but on the other hand, reflected differences in sedimentation processes in different lakes. In some of the lakes the peak still occurred in the uppermost (0–2 cm) sediment layer, but in an extreme case the peak occurred at a depth of 22–23 cm corresponding to a sedimentation rate of 16 mm year⁻¹ during the 14 years after the Chernobyl accident. The total amounts of ¹³⁷Cs in sediments varied from 15 to 170 kBq m⁻² at the sampling stations studied. Since 1990, the amounts have continued to increase slightly in two lakes, but started to decrease in the other lakes. In most of the lakes, the total amounts of ¹³⁷Cs in sediments were about 1.5–2 times higher than in local deposition. In two lakes, the ratio was below 1, but in one case 3.2. Compared with the total amounts of ¹³⁷Cs at the same stations in the late 1960s and 1970s, the values were now at their highest, at about 60-fold. The most important factors affecting ¹³⁷Cs values in sediments were the local amount of deposition and the type of the lake and the sediment, but in addition, there were a number of other factors to be considered.

URL: http://www.sciencedirect.com/science/article/pii/S0265931X0500041X

Justification of remediation strategies in the long term after the Chernobyl accident

Title: Justification of remediation strategies in the long term after the Chernobyl accident

Author: S. Fesenko, P. Jacob, A. Ulanovsky, A. Chupov, I. Bogdevich, N. Sanzharova, V. Kashparov, A. Panov, Yu. Zhuchenka

Reference: Journal of Environmental Radioactivity, Volume 119, May 2013, Pages 39-47

DOI: http://dx.doi.org/10.1016/j.jenvrad.2010.08.012

Keywords: Chernobyl accident; Caesium; Ionizing radiation; Radiation protection; Rehabilitation; Remediation

Abstract: Following the accident at the nuclear power plant in Chernobyl a number of different remedial actions were developed and implemented in Belarus, Russia, and Ukraine. Recommendations on the application of countermeasures and remedial actions were published by the IAEA as “Guidelines for agricultural countermeasures following an accidental release of radionuclides” in 1994. Since then, new information on the behaviour of radionuclides in the environment and effectiveness of countermeasures in the long term has been obtained and reviewed by many projects, including the Chernobyl Forum. Additionally, new approaches to derive remediation strategies were developed and successfully implemented in the most affected countries. This paper describes a justification of the remediation strategies suggested for rehabilitation of the areas most affected by the Chernobyl accident based on this experience.

URL: http://www.sciencedirect.com/science/article/pii/S0265931X10001992

Time-dependent behaviour of radiocaesium: A new method to compare the mobility of weapons test and Chernobyl derived fallout

Title: Time-dependent behaviour of radiocaesium: A new method to compare the mobility of weapons test and Chernobyl derived fallout

Author: J.T Smith, R.T Clarke, R Saxén

Reference: Journal of Environmental Radioactivity, Volume 49, Issue 1, May 2000, Pages 65-83

DOI: http://dx.doi.org/10.1016/S0265-931X(99)00088-0

Keywords: Radiocaesium; Kinetics; Chernobyl; Rivers; Mobility

Abstract: Environmental radiocaesium ( ) originates primarily from two sources, atmospheric nuclear weapons testing, and the Chernobyl accident. It has not, to our knowledge, previously been possible statistically to compare changes in the environmental mobility of from these two sources since the weapons test fallout varied in a complex manner over a number of years. A novel technique is presented for curve-fitting measurements with a time-dependent input function such as that for weapons test fallout. Different models were fitted to measurements of both pre- and post-Chernobyl activity concentrations in five major Finnish rivers. It was shown that there was no significant difference in the temporal changes in mobility from these two sources during the years after fallout. Transport parameters derived from weapons test measurements gave good predictions of the long-term contamination of these rivers by Chernobyl fallout. Changes in activity concentrations in rivers after Chernobyl have previously been shown to decline as a result of slow sorption to clay minerals in catchment soils. It is shown that weapons test fallout also exhibited this slow decline over time. Rates of decline in activity concentrations 10 years after fallout correspond to effective ecological half-lives (Teff) in the range 10–30 years. Removal of activity from the catchment was found to have no significant effect on the long-term decline in activity concentrations in these rivers.

Vertical distribution of radionuclides in soil of a grassland site in Chernobyl exclusion zone

Title: Vertical distribution of radionuclides in soil of a grassland site in Chernobyl exclusion zone

Author: Peter Bossew, Michael Gastberger, Herbert Gohla, Peter Hofer, Alexander Hubmer

Keywords: Chernobyl; Radionuclides; Vertical migration in soil

Abstract: Five soil profiles from a site about 8 km SE of the Chernobyl NPP were investigated for the vertical distribution of radionuclides. The average ¹³⁷Cs-inventory at the site is about 2.6 MBq/m² (reference date 1 May 1986). Apart from ¹³⁷Cs, the following radionuclides have been identified (their activity ratios to ¹³⁷Cs in brackets): ¹³⁴Cs (0.537), ¹²⁵Sb (0.068), ⁶⁰Co (0.0022), ¹⁵⁴Eu (0.016), ¹⁵⁵Eu (0.020), ^94gNb (9.5E-5), ^239/240Pu (0.0088), ²³⁸Pu (0.040), ⁹⁰Sr (0.30) and ²⁴¹Am (0.011). Apparent vertical migration velocities are between 0.14 and 0.26 cm/a, apparent dispersion coefficients range from 0.02 to 0.13 cm²/a. The rankings of the velocities v for different radionuclides are (Sr, Cs, Sb, Co, Pu)<AmD, the following rankings have been found: (Nb, Sr, Cs)<Am<Eu, Csp=0.1 level).

URL: http://www.sciencedirect.com/science/article/pii/S0265931X03002364

Distribution and migration of ⁹⁰Sr in components of the Dnieper River basin and the Black Sea ecosystems after the Chernobyl NPP accident

Title: Distribution and migration of ⁹⁰Sr in components of the Dnieper River basin and the Black Sea ecosystems after the Chernobyl NPP accident
Author: N.Yu. Mirzoyeva, V.N. Egorov, G.G. Polikarpov

URL: http://www.sciencedirect.com/science/article/pii/S0265931X13000489

Resolving Chernobyl vs. global fallout contributions in soils from Poland using Plutonium atom ratios measured by inductively coupled plasma mass spectrometry

Keywords: Chernobyl; Contamination; Plutonium; Poland; Soils; Isotopic ratios; Inductively coupled plasma, mass spectrometry

Abstract: Plutonium in Polish forest soils and the Bór za Lasem peat bog is resolved between Chernobyl and global fallout contributions via inductively coupled plasma mass spectrometric measurements of ²⁴⁰Pu/²³⁹Pu and ²⁴¹Pu/²³⁹Pu atom ratios in previously prepared NdF₃ α spectrometric sources. Compared to global fallout, Chernobyl Pu exhibits higher abundances of ²⁴⁰Pu and ²⁴¹Pu. The ratios ²⁴⁰Pu/²³⁹Pu and ²⁴¹Pu/²³⁹Pu co-vary and range from 0.186 to 0.348 and 0.0029 to 0.0412, respectively, in forest soils (²⁴¹Pu/²³⁹Pu=0.2407×[²⁴⁰Pu/²³⁹Pu]−0.0413; r²=0.9924). Two-component mixing models are developed to ap portion ^239+240Pu and ²⁴¹Pu activities; various estimates of the percentage of Chernobyl-derived ^239+240Pu activity in forest soils range from <10% to >90% for the sample set. The ²⁴⁰Pu/²³⁹Pu–²⁴¹Pu/²³⁹Pu atom ratio mixing line extrapolates to estimate ²⁴¹Pu/²³⁹Pu and the ²⁴¹Pu/^239+240Pu activity ratio for the Chernobyl source term (0.123±0.007; 83±5; 1 May 1986). Sample ²⁴¹Pu activities, calculated using existing alpha spectrometric ^239+240Pu activities, and the ²⁴⁰Pu/²³⁹Pu and ²⁴¹Pu/²³⁹Pu atom ratios, agree relatively well with previous liquid scintillation spectrometry measurements. Chernobyl Pu is most evident in locations from northeastern Poland. The ²⁴¹Pu activities and/or the ²⁴¹Pu/²³⁹Pu atom ratios are more sensitive than ²⁴⁰Pu/²³⁹Pu or ²³⁸Pu/^239+240Pu activity ratios at detecting small Chernobyl ^239+240Pu inputs, found in southern Poland. The mass spectrometric data show that the ²⁴¹Pu activity is 40–62% Chernobyl-derived in southern Poland, and 58–96% Chernobyl in northeastern Poland. The Bór za Lasem peat bog (49.42° N, 19.75° E), located in the Orawsko-Nowotarska valley of southern Poland, consists of global fallout Pu.

URL: http://www.sciencedirect.com/science/article/pii/S0265931X03002522

Kinetics of dissolution of Chernobyl fuel particles in soil in natural conditions

Keywords: Chernobyl; Fuel particles; Dissolution kinetics; Sr-90; Mobility; Soil

Abstract: Kinetic of fuel particles dissolution under natural environmental conditions has been investigated using the data on ⁹⁰Sr speciation in soils collected from 1995 to 1997 within the Chernobyl nuclear power plant 50 km zone. The dependency of fuel particles dissolution constants on the soil acidity (pH=4–7) has been obtained on the basis of large and statistically reliable experimental data. Results show that between 2 and 21% of ⁹⁰Sr activity is associated with weathering resistant fuel particles. Therefore, these particles would not influence the radiological situation in the near future. The map of the main agrochemical characteristics and the map of the fuel particles dissolution constants have been created for the 30-km zone territory. According to the prognosis of dynamics of fuel particles dissolution in the investigated zone, a radiological situation along the fuel paths of radioactive fallout in present time reached a stable state. An increasing in absolute contents of ⁹⁰Sr mobile forms in neutral soils will be observed in the next 10–20 yr. However, the difference between the maximum level of mobile forms contents and their existing contents will not exceed 20%.

Use of 129I and 137Cs in soils for the estimation of 131I deposition in Belarus as a result of the Chernobyl accident

Keywords: Chernobyl; ¹²⁹I; ¹³¹I; ¹³⁷Cs; Soils

Abstract: Using radioactivity measurements for ¹³¹I and ¹³⁷Cs and nuclear activation analysis (NAA) or accelerator mass spectrometry (AMS) for ¹²⁹I, ratios of ¹³¹I/¹³⁷Cs and ¹²⁹I/¹³⁷Cs have been determined in soils from Belarus. We find that the pre-Chernobyl ratio of ¹²⁹I/¹³⁷Cs in Belarus is significantly larger than expected from nuclear weapons fallout. For the Chernobyl accident, our results support the hypothesis that there was relatively little fractionation of iodine and caesium during migration and deposition of the radioactive cloud. For sites having ¹³⁷Cs >300 Bq/kg, ¹²⁹I can potentially give more reliable retroactive estimates of Chernobyl ¹³¹I deposition. However, our results suggest that ¹³⁷Cs can also give reasonably good (±50%) estimates for ¹³¹I in Belarus.

URL: http://www.sciencedirect.com/science/article/pii/S0265931X01000807