Ultrasonic Thermometry for Nuclear Reactors

Ultrasonic thermometry, based on the temperature dependence of sound velocity in solids, has been demonstrated under ideal laboratory conditions beyond 6000R. Integrated fluxes (nvt) of 2.6 × 1019 fast and 8.7 × 1019 thermal do not perturb the velocity/temperature relationship. Ta protective sheaths prevented carbon contamination for 1 hr at 5100R, in a program simulating temperature measurements in the graphite/hydrogen atmosphere of a nuclear rocket engine. Tests have also been performed in liquid sodium at 1200R, and separately, inside a 1.6 mm dia Ta tube heated to 5500R, simulating temperatures inside UO2-fueled pins of fast breeder reactors.