The effects of the physical states of a simulated fission product on the linear thermal expansion of (U0.924Ce0.076)O-2

Abstract

The linear thermal expansions of an (U0.924Ce0.076)O-2 pellet, doped a simulated fission product (Nd2O3 or Ru), were measured from room temperature to 1673 K in a flowing argon atmosphere using TMA. Nd2O3 and Ru represent the physical states of a fission product, a dissolved oxide and a metallic precipitate, respectively. Using the measured data, the mean coefficients of a linear thermal expansion was obtained as a function of the temperature, and the effects of the physical states of a simulated fission product on the thermal expansion were investigated. In the case of the Nd2O3 forming a dissolved oxide, the thermal expansion of the sample increased and the increment was proportional to the Nd contents, because the melting point of the Nd2O3 was lower than that of UO2 and although the metallic precipitate hardly affected the crystal structure, the linear thermal expansion also increased with an increasing Ru contents.