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This paper presents a recent implementation of the radial heat flow method, a classical technique used to measure the thermal conductivity of materials, including the hardware designed to this end, as well as the theoretical formalism used to analyse the data. The novelty is in its application to high-aspect-ratio hollow cylindrical samples, more specifically sections of nuclear cladding tube, whereby samples representative of full length fuel clads can be measured instead of platelets, like in usual laser-flash measurements. The apparatus designed and built to this end can accommodate tubular samples of varying length, diameter and wall thicknesses made of most materials, with the specific goal of determining the through-thickness thermal conductivity of silicon carbide composites, a highly anisotropic material under consideration as a fuel cladding material. [ABSTRACT FROM AUTHOR]

X-rays from synchrotron beamlines provide a powerful tool for materials analysis in circumstances where long-term materials degradation under complex loading conditions ( e.g., temperature, irradiation, and stress) becomes important. This may occur for advanced gas cooled reactors. Synchrotron X-rays can help to improve lifetime assessments by providing a more in-depth understanding of microstructural damage. This article summarizes results of X-ray absorption fine spectrum analysis and X-ray magnetic circular dichroism synchrotron techniques. They were employed to evaluate various microstructural features, which are important in understanding the lifetime of materials exposed to extreme conditions. Dispersoid strengthening by yttria particles, conditions that produce nanocrystal Zircaloy, and the role of magnetism on the stability of ferritic steels were taken as examples. [ABSTRACT FROM AUTHOR]