In situ thermal conductivity measurement of ceramics in a fast neutron environment

A temperature controlled instrumented capsule has been irradiated in the RB * position of the high flux isotope reactor (HFIR) at the Oak Ridge Nationa l Laboratory in order to perform in situ thermal conductivity measurements of monolithic ceramics and composite materials during neutron irradiation. This determination of thermal conductivity utilizes a temperature gradient technique whereby two thermocouples measure the absolute temperature along a cylindrical sample which is constrained to one-dimensional thermal conduc tion. The heat source is the intrinsic gamma heating of the core region of the HFIR. This paper provides an overview of the experiment and gives preli minary results on the degradation in thermal conductivity of a few ceramic specimens measured as a function of irradiation temperature (200-700 degree sC) and fast neutron fluence up to similar to3.4x10(25) n/m(2) (E > 0.1 MeV ). (C) 2000 Elsevier Science B.V. All rights reserved.