[en] The resonance integral of neutron capture on ²⁴⁴Pu is measured by the cadmium ratio method and comparing with a gold sample. The obtained value 40.0+-3.0 b agrees well with the results of investigations carried out earlier

No abstract available

No abstract available

[en] Investigations conducted in the framework of radiation monitoring of Norway sea area, where 'Komsomolets' nuclear submarine sank in 1989, are described.Experimental data about concentrations and isotope content of uranium and plutonium in water samples and bottom sediments are presented.Based on the obtained data, a conclusion about the absence of the weapon fissionable material yield from the submarine to the environment is made

[en] There are carried out the measurements of ²³²Pa integral fission cross-sections by neutrons near the thermal point and by supercadmium neutrons (resonance integral). ²³²Pa production was implemented through ²³²Th(p,n)²³²Pa reaction at bombarding a thick thorium target by a beam of 12 MeV protons. The release of produced ²³²Pa atoms was executed with the help of chromatographic methods. A polyethylene moderating block served as a source of thermal neutrons; fast neutrons were obtained as a result of irradiating beryllium target by a beam of 11.5 MeV deutons of the electrostatic accelerator. The measurements were performed by a relative method, the calibrated layer of ²³⁵U was used as a standard. Fission fragments of ²³²Pa and ²³⁵U were registered by dielectric track detectors. There was analysed the time dependence of the number of fissions for ²³²Pa nuclei, moreover there was separated the exponential component, corresponding to β-decay of ²³²Pa(T_β = 31.44 hours). Resulting from these measurements there were obtained the cross-section values for ²³²Pa fission by neutrons near the thermal point σ_f(²³²Pa) (977 ± 75) b as well as the values of fission resonance integral Ι_f(²³²Pa) = (915 ± 330) b. The experimental data testify that there is available the isomeric state with half-life period equal to ∼ 4.5 hours, which was unknown before. 10 refs., 2 figs

[en] Lichens are widely used to assess the atmospheric pollution by heavy metals and radionuclides. However, few studies are available in publications on using lichens to qualitatively assess the atmospheric pollution levels. The paper presents research results applying epiphytic lichens as bio-monitors of quantitative atmospheric contamination with uranium. The observations were conducted during 2.5 years in the natural environment. Two experimental sites were used: one in the vicinity of a uranium contamination source, the other one - at a sufficient distance away to represent the background conditions. Air and lichens were sampled at both sites monthly. Epiphytic lichens Hypogimnia physodes were used as bio-indicators. Lichen samples were taken from various trees at about 1.5m from the ground. Air was sampled with filters at sampling stations. The uranium content in lichen and air samples as well as isotopic mass ratios ²³⁵U/²³⁸U were measured by mass-spectrometer technique after uranium pre-extraction. Measured content of uranium were 1.45mgkg^-1 in lichen at 2.09E-04μgm^-3 in air and 0.106mgkg^-1 in lichen at 1.13E-05μgm^-3 in air. The relationship of the uranium content in atmosphere and that in lichens was determined, C_AIR=exp(1.1xC_LICHEN-12). The possibility of separate identification of natural and man-made uranium in lichens was demonstrated in principle