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Activity concentrations of 90Sr in fish in lakes located within the Chornobyl Exclusion Zone (ChEZ) reach 100 kBq kg−1, which is several thousand times higher than the permissible level in Ukraine (35 Bq kg−1). This study was conducted in the natural conditions of the ChEZ to determine the effectiveness of keeping radioactively contaminated fish in "clean" water to reduce the 90Sr content of their muscle tissue, as previously shown in short-term laboratory experiments. It was found that transferring tench (Tinca tinca (Linnaeus, 1758)) from Lake Glubokoye one of the most contaminated lakes in the ChEZ, to a cage in the "clean" Lake Starukha for 45 days did not lead to a significant decrease in 90Sr content in both bone and muscle tissues. Establishing permissible levels of 90Sr concentration only in fish fillet, and not in the whole fish body (with bone tissue), is appropriate for human radiation protection, since the retention factors of 90Sr treatment for boiled bone tissue of crucian carp from the Chornobyl exclusion zone are less than 0.01, and up to 97% of strontium is contained in bone tissue. [Display omitted] • No reduce of 90Sr content in contaminated fish when kept in "clean" water for 45 days. • Less than 1% of 90Sr is transferred to broth during boiling of fish bone tissue. • Current Ukrainian permissible levels of 90Sr in fish products need to be revised. • Long-term experiments are needed to study ways to remove 90Sr from fish tissues. [ABSTRACT FROM AUTHOR]

Microscopic fuel fragments, so-called "hot particles", were released during the 1986 accident at the Chornobyl nuclear powerplant and continue to contaminate the exclusion zone in northern Ukraine. Isotopic analysis can provide vital information about sample origin, history and contamination of the environment, though it has been underutilized due to the destructive nature of most mass spectrometric techniques, and inability to remove isobaric interference. Recent developments have diversified the range of elements that can be investigated through resonance ionization mass spectrometry (RIMS), notably in the fission products. The purpose of this study is to demonstrate the application of multi-element analysis on hot particles as relates to their burnup, particle formation in the accident, and weathering. The particles were analysed with two RIMS instruments: resonant-laser secondary neutral mass spectrometry (rL-SNMS) at the Institute for Radiation Protection and Radioecology (IRS) in Hannover, Germany, and laser ionization of neutrals (LION) at Lawrence Livermore National Laboratory (LLNL) in Livermore, USA. Comparable results across instruments show a range of burnup dependent isotope ratios for U and Pu and Cs, characteristic of RBMK-type reactors. Results for Rb, Ba and Sr show the influence of the environment, retention of Cs in the particles and time passed since fuel discharge. [Display omitted] • The advantages of resonance ionization mass spectrometry for nearly non-destructive micro analysis of isotope ratios. • Considering the effects of nuclear reactions and particle formation in the accident on the resulting isotope ratios. • Assessing the origin of particles, time since release from the reactor, and retention of elements in the particles. [ABSTRACT FROM AUTHOR]

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. [Copyright &y& Elsevier]

Abstract: The Urban Remediation Working Group of the International Atomic Energy Agency''s EMRAS (Environmental Modelling for Radiation Safety) program was organized to address issues of remediation assessment modelling for urban areas contaminated with dispersed radionuclides. The present paper describes the first of two modelling exercises, which was based on Chernobyl fallout data in the town of Pripyat, Ukraine. Modelling endpoints for the exercise included radionuclide concentrations and external dose rates at specified locations, contributions to the dose rates from individual surfaces and radionuclides, and annual and cumulative external doses to specified reference individuals. Model predictions were performed for a “no action” situation (with no remedial measures) and for selected countermeasures. The exercise provided a valuable opportunity to compare modelling approaches and parameter values, as well as to compare the predicted effectiveness of various countermeasures with respect to short-term and long-term reduction of predicted doses to people. [Copyright &y& Elsevier]