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Ion induced millimetre-scale structures growth on metal surfaces
Girka, O.,Bizyukov, O.,Balkova, Y.,Myroshnyk, M.,Bizyukov, I.,Bogatyrenko, S. Elsevier 2018 Nuclear instruments & methods in physics research. Vol.420 No.-
<P><B>Abstract</B></P> <P>Polished polycrystalline Plansee tungsten (W) sample with purity 99.99 wt% and 0.75 mm thickness has been exposed to intense argon (Ar) ion beam with average energy of 2 keV and etched through in the centre. As a result, castle-like structures with strong asymmetry and with the height of >200 µm have been formed. Structures can be observed by naked eyes and with scanning-electron microscopy (SEM). It has been revealed, that the structures have been formed not immediately, but at the later stages of irradiation. Primary factors favouring the formation for the structures are relaxation of the surface stresses and activated surface mobility of atoms.</P>
Aluminium and titanium alloys surface behaviour under argon and helium ion exposure
Bizyukov, I.,Girka, O.,Kaczmarek, Ł.,Klich, M.,Myroshnyk, M.,Januszewicz, B.,Owczarek, S. Elsevier 2018 Nuclear instruments & methods in physics research. Vol.436 No.-
<P><B>Abstract</B></P> <P>Samples of aluminium alloy 2024 and titanium alloy Ti-6Al-4V are irradiated with 2 keV helium (He) and argon (Ar) ion fluxes using FALCON ion source. Cone-like structures are found to be formed on the surface of two Al(2024) samples due to both irradiation conditions: Ar and He ions exposure reaching total fluence 9.75 × 10<SUP>25</SUP> m<SUP>−2</SUP> and total charge 150 Coulomb per sample. Ar ions exposure of Ti-6Al-4V causes cones formation, while exposure for He ions causes only physical sputtering morphology at the same fluence. Chemical composition of grown structures is obtained from energy dispersive spectroscopy (EDS). Surface roughness and roughness profile are investigated with confocal microscope. Hardness of irradiated surfaces is obtained from results of Vickers hardness test. Residual stresses after irradiation and phase composition are measured by X-ray Diffraction spectroscopy (XRD). The mechanisms of cones growth on alloys surface are surface radiation-stimulated diffusion and ion induced collision cascades evolution.</P>
Rudychev, V.G.,Azarenkov, N.A.,Girka, I.O.,Rudychev, Y.V. Korean Nuclear Society 2021 Nuclear Engineering and Technology Vol.53 No.11
The characteristics of the external radiation on the surface of the casks for spent nuclear fuel (SNF) storage by dry method are investigated for the case when the spatial distribution of SNF in the basket changes due to the destruction of the fuel rod claddings. The surface areas are determined, where the changes in fluxes of neutrons, produced by <sup>244</sup>Cm actinide, and γ-quanta, produced by long-lived isotopes, are maximum in the result of the decrease in the height of the SNF area. Concrete (VSC-24) and metal (SC-21) casks are considered as examples. The procedure of periodic measurement of the dose rate of neutrons or γ-quanta at the specified points of the cask surface is proposed for identifying the fuel rod cladding destruction. Under normal operation, the decrease in the dose rate produced by neutrons as the function of SNF storage duration is determined by the half-life of <sup>244</sup>Cm, and for γ-quanta - by the half-lives of long-lived SNF isotopes. Consequently, a stepwise change in the dose rate of neutrons or γ-quanta, detected by the measurements, as compared to the previous one, would indicate the destruction of the fuel rod claddings.
Optimization of radiation shields made of Fe and Pb for the spent nuclear fuel transport casks
Rudychev V.G.,Azarenkov N.A.,Girka I.O.,Rudychev Y.V. 한국원자력학회 2023 Nuclear Engineering and Technology Vol.55 No.2
Recommendations are given to improve the efficiency of radiation protection of transport casks for SNF transportation. The attenuation of g-quanta of long-lived isotopes 134Cs, 137mBa(137Cs), 154Eu and 60Co by optimizing the thicknesses and arrangement of layers of Fe and Pb radiation shields of transport casks is studied. The fixed radiation shielding mass (fixed mass thickness) is chosen as the main optimization criterion. The effect of the placement order of Fe and Pb layers in a combined two-layer radiation shield with an equivalent thickness of 30 cm is studied in detail. It is shown that with the same mass thicknesses of the Fe and Pb layers, the placement of Fe in the first layer, and Pb - in the second one provides more than twofold attenuation of g-quanta compared to the reverse placement: Pb - in the first layer, Fe - in the second. The increase in the efficiency of attenuation of g-quanta for TC with combined shielding of Fe and Pb is shown to be achieved by designing the first layer of radiation shielding around the canister with SNF from Fe of the maximum possible thickness.