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Self-irradiation can affect durability of glasses used to immobilize high-level nuclear waste (HLW). The stability of glasses can also be indirectly affected by the radiolytic changes in contact water leading to decrease in its pH although this is unlikely to occur for disposal systems where the interaction of groundwater with glass is delayed to times when radiation dose rates are decreased to levels insignificant to cause such effects. Besides, interaction of the water influenced by radiation with other repository protective elements (container and bentonite) will suppress the radiolytic changes. Literature analysis shows practical absence or very weak effect of self-irradiation on structure and characteristics of borosilicate glasses with typical content of nuclear waste. Data for aluminophosphate glass used in Russia have showed that, after γ-irradiation with a dose of 6.2·107 Gy, the leaching rates of elements were decreased approximately twice relatively to pristine samples.

Linear stability analysis and numerical simulations of density‐driven flow are presented in order to estimate the effects of temperature‐dependent fluid viscosity variation on the onset of free thermal convection within a three‐dimensional fault embedded into impermeable rocks. The strongly coupled equations of density‐driven flow are linearized. The solution was obtained through expansion into Fourier series. Simple polynomial expressions fitting the neutral stability curves are given for a range of fault aspect ratios, fluid viscosity properties, and thermal conductivity heterogeneity, providing a new tool for the estimation of critical Rayleigh numbers in faulted systems. The results are validated against the limiting case of temperature‐invariant viscosity (i.e., constant). 3‐D numerical simulations of free convection within a fault are run using the finite element technique in order to verify the theoretical results. It turned out that at average geothermal temperature conditions, thermal convection can develop within faults which permeability is up to 4 times lower than the case of a fluid with constant viscosity, in agreement with the developed linear theory. The polynomial expressions of this study can be applied to any numerical model for testing the feasibility of fault convection in 3‐D geothermal basin.

Tip-enhanced Raman spectroscopy is considered a promising technique for imaging with nanoscale lateral resolution. However, its developments and use face many problems. In this paper we provide insight into the level of sample heating by the laser light in the presence of a metal-coated atomic force microscope (AFM) tip. The heating is attributed to the presence of an optical field enhanced by the tip. Sample temperatures were estimated using measurements of the ratio of the Stokes and anti-Stokes signals from a thin 50-nm sample on an Al substrate. A correlation between the heating and optical properties of the tips is established. The results demonstrate significant tip-induced heating (100 K and more) even at very low laser power. Copyright