Vapor Pressure Measurements of Oxide Fuel Between 3000 and 5000 K Using Laser Heating

Abstract

Safety analysis of fast reactors requires knowledge of the vapor pressure of the fuel material under the condition of rapid heating in the temperature region from 3000 K upwards, where up to now no measured data have been available. An experimental technique to determine the vapor pressure of refractory fuel materials in the temperature range between 3000 and 5000 K is based on laser beam heating of the specimen surface for ∼1 msec and measurement of both the recoil momentum of the specimen and the mass and momentum carried away by the vapor jet flowing into a vacuum. The determination of the vapor pressure requires application of gas dynamics and development of a suitable mode. The application limits of such a measuring technique using laser heating and the reliability of the vapor pressure data thereby determined have been assessed.