Application of a new thermochemical measurement method for nuclear materials at temperatures beyond 3000 K

In processing and end-use environments, and particularly nuclear fission reactor excursions, inorganic materials can be subjected to temperatures where liquids and vapors are significant components of the materials system. Classical characterization and thermochemical methods fail at temperatures beyond about 3000 K, due to the reactivity of container materials. Use of a pulsed laser beam as a localized heat source avoids this limitation. Coupling laser heating with molecular beam sampling and mass- and optical-spectroscopy allows us to characterize the thermochemistry of liquid-vapor systems at temperatures of 3000-5000 K, pressures of 0.01-20 bar (1 bar = 10 5 Nm 2 ). and on a nanosecond order-of-magnitude time scale. Materials considered here include C, ZrO 2 , Y 2 O 3 and HfO 2 . New approaches for temperature measurement and for pressure determination, using electron impact mass spectral data coupled with deposition rate measurements, are described.