A thermal conductivity and electromotive force measurement system for nuclear fuels and materials

Abstract

The development of advanced nuclear fuels requires a better understanding of their transmutation and microstructural evolution. Alloy fuels have the advantage of high thermal conductivity and improved characteristics in fuel-cladding chemical reaction. However, information on thermodynamic and thermophysical properties is limited. The objective of this research is to develop an experimental system, integrated with the thermal conductivity measurement by the comparative cut-bar technique to measure the thermodynamic properties of solid materials, from which an understanding of their phase change(s) can be determined. With the coupled system, thermal conductivity and electromotive force (EMF) can both be measured. In order to calibrate and test the system, the apparatus was employed to measure the EMF of several materials. As an initial calibration test, the EMF of Chromel was measured from 100 °C to 800 °C and compared with theoretical values. The subsequent material structure determination process was performed by EMF measurement of pure iron, iron-nickel alloy and ANSI 1018 carbon steel rods. The measured phase transition temperatures were compared with the corresponding alloy equilibrium phase diagrams. The results indicate that the system is able to determine material phase change based on EMF measurement. In the future, this prototype system is to be eventually modified and used in a hot-cell on irradiated samples.