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  • Author or Editor: M. Nikonov x
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Abstract  

A kinetic isotope effect in Pu(V) disproportionation has been observed in nitric acid solution under the effect of power ultrasound with intensity 0.9W·cm–2 and frequency 22 kHz. The isotope separation coefficient for242Pu/239Pu isotopes was found to be 1.0081 at 20°C. Without sonication the k.i.e. was not observed. The rate constant of Pu(V) disproportionation was found to be accelerated under sonication. The rate constant determined was (5.7±0.6)·10–3 12·mol–2·s–1 atl=0.9 W·cm–2,v=22 kHz, [HNO3]=0.5 mol·l–1 andT=20°C. It is supposed that the acceleration of Pu(V) disproportionation and the kinetic isotope effect are due to the activation of plutonoyl groups in the interface between the cavitation bubble and the bulk solvent.

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Abstract  

Experience in the use of epithermal neutron activation analysis (ENAA) in the monitoring of atmospheric deposition by means of moss, lichens and pine needles is summarized. It is shown that 45 elements (Mg, K, Ca, Al, Cl, Sc, V, Cr, Mn, Fe, Co, Ni (using (n,p)-reaction), Zn, Cu, As, Se, Br, Rb, Sr, Zr, Mo, Ag, Sn, Sb, I, Cs, Ba, La, Ce, Nd, Sm, Eu, Gd, Tb, Tm, Yb, Lu, Hf, Ta, W, Au, Th and U, as well as Ir and Re in pine needles in the presence of anthropogenic pollution by the nickel mining plant) are reliably determined. Examples of the use of lichens, moss and pine needles as biomonitors of atmospheric deposition in Franz Josef Land the Kola peninsula and in the Tver region are given.

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Journal of Radioanalytical and Nuclear Chemistry
Authors:
K. Bunzl
,
M. Puhakainen
,
I. Riekkinnen
,
P. Karhu
,
W. Schimmack
,
T. Heikinnen
,
T. Jaakkola
,
V. Nikonov
,
V. Pavlov
,
T. Rahola
,
K. Rissanen
,
M. Suomela
,
M. Tillander
, and
M. Äyräs

Abstract  

The industrial pollution of an ecosystem, e.g., by heavy metals, might also affect the behavior of fallout radionuclides in the soils of these areas. To study such effects, we determined at various distances from the huge copper-nickel smelters at Monchegorsk on the Kola Peninsula (Russia) and at a reference site: (1) the vertical distribution of fallout 137Cs,90Sr and239+240Pu in the soil, (2) the corresponding residence half-times in different soil horizons, and (3) the resulting external gamma-dose rates at these sites in 1 m height due to 137Cs in the soil. The data show that the residence half-times and the partitioning of the fallout radionuclides among the various soil horizons depend significantly on the extent of the heavy metal pollution at the sites. The resulting external gamma-dose rate in 1 m height due to 137Cs in the soil is, however, rather similar at the various sites.

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