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  • Author or Editor: Ľ. Mátel x
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Abstract  

NMR, IR and MS were used for identification of major products of radiolysis of benzo-15-crown-5 in chloroform. The crown ether exhibits high affinity towards inorganic products of radiolysis of chloroform resulting in the formation of complexes.

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Abstract  

The radiation-induced oxidation of bis/1,2-dicarbollyl/cobalt/III/ acid to 8-monohydroxy-, and 8,8-dihydroxy-derivatives was observed in two-phase system of 4 to 96 vol. % of CCl4 and H2O. Carbon tetrachloride increases the radiation yields of the oxidation of the acid in the investigated dose region, nature of the radiolytic products being the same. The partial radiation yields in the system were ascertained.

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Abstract  

The partition coefficient of strontium upon its extraction from the aqueous solutions of picric acid into chloroform containing DC-18-crown-6, B-15-crown-5 after their exposition to gamma radiation has been studied. A significant decrease of the partition coefficient in the studied range of doses 10–70 kGy was observed. This effect can be attributed to the radiolytic products of chloroform. The radiation destruction as well as dehydrogenation of crown ethers were not observed.

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Abstract  

The radiation-induced oxidation of bis/1,2-dicarbollyl/cobalt/III/ acid by OH radicals in deaerated/aerated aqueous solutions has been investigated. 8-Monohydroxy-, and 8,8-dihydroxy-derivatives have been identified as products of the -radiolysis. For the different conditions the following radiationchemical yields were observed: in the presence of N2 atmosphere G/OHDCC/=1.58, in aerated solution 2.11 and 3.04 in a solution saturated with CCl3.

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Abstract  

A scaling model was built to calculate the activity of alpha emitting radionuclides in contaminated soil in the lysimeter field. Linear regression can be applied for the evaluation of radioactivity measurement data. Activities of the radionuclides 241Am, 238Pu, 239,240Pu and 90Sr obtained by experiments from real contaminated soils of the experimental lysimeter placed in a nuclear power plant (NPP) in Slovakia were evaluated using linear regression models with the method of least squares. A suitable scaling model for monitoring the 241Am, 238Pu, 239,240Pu alpha radionuclide activity was built using the regression triplet analysis and regression diagnostics. A regular designed scaling model opens the possibilities of longtime activity monitoring of these radionuclides, thus decreasing the number of necessary radiochemical analyses. The Fisher-Snedecor test, however, confirmed that the regression model for 90Sr activity monitoring by 241Am, 239,240Pu activity determination in contaminated soils can not be recommended.

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Abstract  

The effect of Aldrich humic acid (HA) on the mobility of137Cs,85Sr,152Eu and239Pu radionuclides was studied in Ca-montmorillonite suspensions. Verified 2-sites-2-species (2s2s) models correspond to an intensive interaction of all elements with humificated surface, what is in a remarkable contrast with the weak complexation of cesium and even strontium in solutions — the neutral ligand interaction constants β (l/mol) are log β<−9.9 and 7.56±0.21 for Cs and Sr, respectively. The result for europium complexation in solution, log β=12.49±0.18 is in a good agreement with literature data. For plutonium(IV) not only a high proton competitive constant in solution was obtained, log β β=(−0.67±0.32)+3pH, but also a strong chemisorption, which at high concentrations of humic acid (above 0.05 g/l) indicates the formation of bridge humate complexes of plutonium on the humificated surface. Logarithms of heterogeneous interaction constants (

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24 l/g) of the elements with surface humic acid are 4.47±0.23, 4.39±0.08, and 6.40±0.33 for Cs, Sr, and Eu(III), respectively, and the logarithm of the proton competitive constant (
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24, l/g) for Pu(IV) −3.80±0.72. Distribution coefficients of humic acid and metal humates between 0.01 g HA/l solution and montmorillonite were derived as logK d(AH)=−1.04±0.11, logK d(EuA)=1.56±0.11 and logK d(PuA)=2.25±0.04, while the values for Cs and Sr were obtained with very high uncertainty. Speciation of the elements on montmorillonite surface is illustrated as a function of equilibrium concentration of humic acid in solution and of pH.

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Abstract  

The development of a rapid and reproducible method for the separation of plutonium from soil samples is described. Tetravalent plutonium is extracted from 8M HNO3 into 30% Aliquat-336/toluene mixture. Uranium and thorium are removed with nitric and hydrochloric acid washes. Plutonium is backextracted with HCl–H2C2O4 and HCl–HF solutions. Plutonium is coprecipitated with NdF3 and filtrated onto a 0.1–0.2 m membrane filter to prepare a source for -spectrometry. The chemical yields of separation are about 50–60%.

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Abstract  

The adsorption of cesium and strontium ions from water solutions on zeolite has been investigated in presence of sodium, potassium, magnesium and calcium ions. Distribution ratios of cesium and strontium on the zeolite were determined in solutions of various compositions and solution volume to sorbent weight ratios (batch factor). Breakthrough curves for zeolite layers are reported.

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Abstract  

14C releases in the stack air of the NPPs V1 and V2, Jaslovske Bohunice was determined during the year 2004–2010. Radioactivity concentration of 14C in the stack air was determined in the forms of inorganic 14CO2 and 14CnHm. The annual average activity concentration in the stacks air samples varies between 12 and 121 Bq m−3. NPP V1, starting with 45 Bq m−3 in 2005 is decreasing due to the shutting down of the reactors (the first reactor was shut down in December 2006 and the second reactor in December 2008). The average value of radioactivity concentration for power unit V2 was 32 Bq m−3 in 2004 and reached the value of 102 Bq m−3 in the first-quarter of the 2010. The average normalized yearly discharge rates were between 0.39 and 0.64 TBq GWe −1 year−1 (2005–2008), NPP V1 and 0.19–0.61 TBq GWe −1 year−1 (2004–first-quarter 2010) for NPP V2, Jaslovske Bohunice. Most of the discharged 14C is in a hydrocarbon form, (95% for Jaslovske Bohunice NPP V2), but the CO2 fraction may reach 37% in the air stack for Jaslovske Bohunice V1.

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Abstract  

A rapid separation method has been developed which allows measurement of plutonium, americium and strontium isotopes in the radioactive sludge from Nuclear power plant A1 Jaslovske Bohunice (NPP A1) with high chemical recoveries and effective removal of matrix interferences. This method uses different commercial products stacked AnaLig® Pu02, AnaLig® Sr01 and TRU® Resin cartridges from IBC Advanced Technologies and Eichrom Technologies. The method allows the rapid separation of plutonium, strontium and americium using a single multi-stage column in the vacuum box (cartridge technology) with rapid flow rates to minimize sample separation time. The 239,240Pu, 238Pu and 241Am were determined by alpha spectroscopy, 90Sr was counted on TRICARB 2900 TR by Cerenkov counting of its progeny 90Y.

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