Thermal conductivity changes in graphites and carbon/carbon fiber materials induced by low neutron damages

Neutrons produced by the D/T reaction will change the properties of carbon materials. Among these problems, the decrease of thermal conductivity caused by neutron irradiation is a most serious concern. It is expected that the thermal conductivity degradations may significant, even at very low doses, particularly at low irradiation temperature < 600°C. To quantify these effects, an experimental study of the neutron-induced thermal conductivity changes has been performed. Fine and superfine grained graphites, carbon/carbon fiber composites and an oriented pyrolytic graphite have been irradiated in the Pool Side Facility (PSF) of the High Flux Reactor (HFR Petten). These materials have undergone neutron damage between 10−4 to 10−1 graphite displacement per atom (dpa g), at two irradiation temperatures: 400 and 600°C. This paper presents the results of the experiments and the consequences are discussed.