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  • Author or Editor: N. Vajda x
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Summary  

Two types of films were tested and compared for the purposes of film autoradiography. Commercial black and white photographic film proved to have the highest sensitivity and the best resolution. The film was calibrated by specially prepared sources that contained alpha- and beta-emitting isotopes in the form of particles. Application examples for hot particle identification using the developed film autoradiographic technique are given.

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Abstract  

Samples of natural and fertilised soils were collected from Al-Gheran region, west of Tripoli, Libya. The samples were investigated by means of INAA and ED-XRF for Al, Si, K, Ca, Sc, Cr, Mn, Fe, Co, Zn, Br, Rb, Sr, Y, Zr, Nb, Cs, Ba, Hf, Ta, Pb and Th. The results indicate that the concentrations of K, Ca, Zn, Sr and Pb are 2–4 fold higher in fertilised compared to natural soil, while the concentrations of Al, Si, Cr, Mn, Fe, Co, Rb, Y, Nb, Cs, Ba Ta and Th are nearly the same in all samples. Mn and Fe values in two arable soils have been found to be 4–6 times lower than the average concentration in the earth's surface soils. This study concludes that, although the levels of some trace elements important for human health are very low in both natural and fertilised soils. Further research is needed to understand the full significance of the distribution transfer and toxicity of trace elements introduced in imported fertilisers.

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Abstract  

A combined radiochemical separation method has been developed that enables the simultaneous determination of 234U, 235U, 238U, 237Np, 239,240Pu, 238Pu, 241Am, 242Cm, and 244Cm in medium and low level liquid radioactive wastes. The main steps of the method are sample destruction, co-precipitation on iron(II)-hydroxide and calcium-oxalate, separation by extraction chromatography using supported dipentyl-pentyl phosphonate (UTEVA) and supported N,N-octylphenyl-di-i-butylcarbamoylmethyl phosphine oxide with tributyl phosphate (TRU), and α source preparation. The key parameter of the method is the adjustment of the oxidation states of the actinoides before adding the sample onto the UTEVA column. It has been determined that (NH4)2S2O8 can be used for oxidation state adjustment resulting sufficient chemical yields.

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Abstract  

Several sorbents were prepared by precipitating zirconium phosphate on activated carbon support material. The main parameters of the chemical procedure were optimized in order to obtain the highest decontamination factors which can be achieved in the case of Cs+, Sr2+ and I ions. For the characterization of the sorbents, sorption isotherms and capacity data were determined. The reproducibility of the preparation is about 10%.

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Abstract  

A combined radioanalytical method for determination of 93Zr and 237Np (as well as other actinoids) in radioactive wastes has been developed. Analytes were co-precipitated on iron(II)-hydroxide, separated and purified on UTEVA columns, and detected by inductively coupled plasma mass spectrometry. According to Zr and Np, 65 and 75% yields were achieved, respectively.

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Abstract  

The majority of long-lived radionuclides produced in the nuclear fuel cycle can be regarded as “difficult-to-measure” nuclides, hence chemical separation is needed before the nuclear measurement of them. A combined radiochemical procedure that enables the simultaneous determination of some “difficult-to-measure” nuclides in medium and low level radioactive wastes has been developed in our laboratory. Recently, this method has been extended for determination of 237Np and 93Zr. 237Np and 93Zr are pre-concentrated by co-precipitation on iron(II) hydroxide and zirconium oxide, separated by extraction chromatography using UTEVA, and measured by inductively coupled plasma mass spectrometry (ICP-MS). As even traces of polyatomic ions and isotopes at m/z 237 or 93 cause considerable interferences during ICP-MS detection, a purification step by extraction chromatography was needed. Analyzing real samples (evaporation concentrates of a nuclear power plant) 66–99% and 31–99% chemical yields were achieved for Np and Zr, respectively.

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Abstract  

The concentration of 35 elements (Al, As, B, Ba, Be, Ca, Cd, Co, Cl, Cr, Cu, Fe, K, Mg, Mn, Mo, N, Na, Ni, P, Pb, Rb, S, Sb, Sc, Si, Sr, Tb, Th, Ti, U, V, Yb, Zn and Zr) in six different imported, NPK, NP and K fertilizers were determined by ICP-OES in two different laboratories and by INAA. The fertilizers were labeled as 24/12 (Belgium), 46/18 (Morocco), 50% ammonium sulfate 50% K2O (Belgium), New 24/12 (Belgium), 16.8.24 (France) and 17.17.17 (France). It is clear that these fertilizers vary widely in their heavy metals and uranium content, and the accumulation of certain elements in vitally important media such as water, soil and food is undesirable from the medical point of view. The results obtained were acceptable and intercomparison between various methods was carried out.

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Abstract  

A rapid and simple sample preparation method for plutonium determination in environmental samples by inductively coupled plasma sector field mass spectrometry (ICP-SFMS) and alpha-spectrometry is described. The developed procedure involves a selective CaF2 co-precipitation for preconcentration followed by extraction chromatographic separation. The proposed method effectively eliminates the possible interferences in mass spectrometric analysis and also removes interfering radionuclides that may disturb alpha-spectrometric measurement. For 239Pu, 240Pu and 241Pu limits of detection of 9.0 fg·g−1 (0.021 mBq), 1.7 fg·g−1 (0.014 mBq) and 3.1 fg·g−1 (11.9 mBq) were achieved by ICP-SFMS, respectively, and 0.02 mBq by alpha-spectrometry. Results of certified reference materials agreed well with the recommended values.

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Abstract  

A simple and rapid method has been developed for the separation and determination of total radiostrontium in soil. The method consists of three basic steps: oxalate precipitation to remove bulk potassium, chromatographic separation of strontium from most inactive and radioactive interferences utilizing a crown ether (Sr. Spec, EIChroM Industries, Il. USA) and oxalate precipitation of strontium to evaluate the chemical yield. Radiostrontium is then determined by liquid scintillation counting of the dissolved precipitate. When 10 g samples of soil are used, the sensitivity of the method is about 10 Bq/kg. The chemical yield is about 80%. The separation and determination of radiostrontium can be carried out in about 8 hours.

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