Determination de la temperature de fonctionnement d'un combustible irradie a l'aide de moniteurs disperses

Abstract

A specific isothermal line can be precisely located in a compact of irradiated uranium dioxide, using the method of dispersed monitors. This novel technique depends on the use of alumina powder dispersed in the uranium dioxide and location of the eutectic radius corresponding to the 1915 °C isothermal line. The addition of a small proportion of alumina does not affect the thermal conductivity of solid uranium dioxide but has a pronounced effect on the grain size and on the columnar structure. Results are presented of thermal simulation tests, and of irradiation experiments. The new method is briefly compared with the use of fusible metal wires and with the examination of the grain structure of pure uranium dioxide. The eutectic isotherm can be located to within about 0.1 mm.