Radioactive aerosols released from the Chernobyl Shelter into the immediate environment.

The release of radioactive particles through large gaps in the containment of the destroyed Chernobyl reactor was assessed during two measurement periods. In 1996-1999, a total radionuclide flow rate of 274 Bq s(-1) or 8.64 x 10(9) Bq year(-1) was determined. These releases were predominantly due to (137)Cs (78.5%), (90)Sr (21.1%), and (239+240)Pu (0.4%). The mean activity concentration in the aerosol measured directly at the gaps was about 240 mBq m(-3) with an activity median aerodynamic diameter (AMAD) of 2.4 microm for (137)Cs, 120 mBq m(-3) with an AMAD in the range 3.1-13 microm for (90)Sr, 1.8 mBq m(-3) with an AMAD in the range 3.5-11 microm for (239+240)Pu, and 2.0 mBq m(-3) with an AMAD of 1.5 microm for (241)Am. The resulting total inhalation dose rate calculated close to the gaps was about 100 nSv h(-1). In the near environment, the mean (137)Cs activity in the aerosol was 2.2 mBq m(-3) with an AMAD of 2.2 microm, which gave rise to an inhalation dose rate of about two orders of magnitude lower than the corresponding dose rate at the gaps. Occasionally, however, dose levels were measured in the near environment that were similar to those at the gaps. In 2000-2003, lower activity concentrations were observed. The decrease was more pronounced at the gaps than in the near environment. The results indicate that effective dose due to inhalation must be considered for the dose assessment of construction workers who will be deployed at the Chernobyl site to reconstruct the old or to build the new Shelter, in the future.

[Radio-ecological and hygienic assessment of consequences of forest fires in the areas polluted during the Chernobyl accident]. / Radioékologicheskaia i gigienicheskaia otsenka posledstvii lesnykh pozharov na territorii, zagriaznennoi v rezul'tate Chernobyl'skoi avarii.

Retransfer of radionuclides on the condensation trails of Chernobyl radioactive fallouts during forest fires has been experimentally evaluated and their mathematical transfer model verified. It has been shown that radionuclide retransfer will make no great impact on additional pollution of an area even under the most unfavourable conditions. The contribution of convective and non-convective components of transfer to the formation of a radioactive aerosol concentration field has been assessed. Time course of changes in the concentration of radioactive aerosol and its dispersive composition are shown in different phases of fire and at different distance from its source.

Measurement of resuspended aerosol in the Chernobyl area. Part II. Size distribution of radioactive particles.

Size distribution measurements of particulate radionuclides were performed at two sites in the Chernobyl 30-km exclusion zone using several cascade impactors. The results obtained in the period September 1986 till June 1993 were discussed with regard to the general assumption of a log-normal activity size distribution in inhalation dose assessment. At Zapolie (a site 14 km from the Chernobyl reactor) a bimodal distribution was observed in 91% of all measured distributions. In most cases the medians were about 4 microns and in the range 20-30 microns. According to soil granulometric data this finding was explained by superimposing two processes: local resuspension and advective transport of radioactive aerosol from highly contaminated territories. The mean air concentration showed an increasing proportion of inhalable particles over the years since the accident. In 1993 the inhalable fraction was about 48% of the total concentration. At Pripyat, a site situated within a highly contaminated area, unimodal types of size distributions were predominant with the median diameters in the range 5-10 microns for 137Cs. For the three nuclides 137Cs, 144Ce and 106Ru, very similar types of distribution were observed. Apparently, the radioactive aerosol was of fuel origin. During a forest fire at a distance of 17 km, the majority of the radioactivity was associated with submicrometer particles with median diameters in the range 0.28-0.50 micron.

Measurement of resuspended aerosol in the Chernobyl area. I. Discussion of instrumentation and estimation of measurement uncertainty.

Results of measurements of the resuspended radioactive aerosols in the Chernobyl area are presented which were obtained soon after the Chernobyl reactor accident and in a European project in 1992-1993. The measurements were carried out with the intention of obtaining a data base for dose assessment of resuspended radioactive particles. Potential significant dose contributions may result from inhalation and secondary contamination due to resuspended radionuclides. In this first article of a series of three papers, the instrumentation and the measurement uncertainties are discussed. An effort was made to sample quantitatively giant aerosol particles (particles larger than 10 microns aerodynamic diameter) as well. The comparison of the samplers shows, in general, an agreement of concentration measurements of 137Cs and 7Be within a factor of two. One sampler was identified with larger discrepancies and needs additional investigation of its sampling characteristics; for another device, the recalibration of the analysing system is recommended. Ordinary integrating samplers have a loss of about 30% in 137Cs activity compared to an isokinetic sampler collecting giant particles as well. The mean ratio of 137Cs activity concentration between an instrument sampling only particles larger than 10 microns and an ordinary integrating sampler is 0.39 +/- 0.15 during anthropogenic-enhanced resuspension. These findings demonstrate the significant contribution of giant particles to resuspended airborne radioactivity. The results of this study concerning integral measurements during wind-driven resuspension proved to be in good agreement with previously published data on resuspension.

[Thermal restructuring and hydration of serum albumin]. / Termicheskie perestroiki i gidratsiia syvorotochnogo al'bumina.

Calorimetry and dielectrometry in the millimeter wave range have been applied to demonstrate a possibility for determination of heat capacity of bound water in biopolymer matrices in solution is shown. Variation of the hydration level of human serum albumin caused by the variation of temperature and protein concentration is described. Application of two methods based on comparison of calorimetric and dielectric data on protein solutions at different temperatures and concentrations have produced similar values of the heat capacity of bound water in the protein hydration shell (approximately 3 J/g.K).

[Hydration and stability of the B-form of LiDNA]. / Gidratatsiia i stabil'nost' B-formy LiDNK.

Hydration and structure of Li DNA in films and solutions have been investigated by methods of IR spectroscopy, piezogravimentry, UHF dielectrometry, and microcalorimetry. The hydration energy and the water sorption range in which the DNA undergoes the transition from the unordered state to the B-form have been determined, making it possible to evaluate the contribution of water molecules of the DNA hydration shell to the total stabilization energy of the DNA helical structure.

[Physical properties of the DNA-water system]. / Fizicheskie svoistva sistemy DNK-voda.

The review of original and literary data obtained by the different physical methods on the structure, mechanical, electrostatic and energetic properties of DNA-ions-water system was done. On the basis of the examined results the main problem of DNA structure formation its dynamic and stability were discussed.

[Globular protein hydration by a differential dielectrometric method]. / Issledovanie gidratatsii globuliarnykh belkov differentsial'nym dielektrometricheskim metodom.

A differential method is described for measuring dielectric constants and losses in aqueous protein solutions at millimetrerange wavelengths. Employment of the method allows to improve the accuracy of determining the degree of hydratation. A method has also been suggested for taking into account the contribution of ions to the dielectric constant of solutions. The differential method was used to study hydratation of nine globular proteins. The data obtained are compared with the corresponding values provided by other experimental techniques and with theoretical predictions based on some models of hydratation. Good agreement is obtained with results provided by the isopiestic and NMR techniques. The discrepancy shown for hemoglobin is discussed in the paper. As has been shown, the dielectric method registers a monomolecular surface layer of water only. With pH varying between 4.0 and 3.2, a significant increase is observed in the hydratation of serum albumin. Presumably, this effect is connected with a N--F conformational transition.