Analysis of Thermal Diffusivity of Specimens with Sample Holder Design in Laser Flash Apparatus

Many experiments for a thermal conductivity of a nuclear fuel were carried out to observe a change of the thermal diffusivity with the burnup. To measure the thermal conductivity, three parameters such as thermal diffusivity, thermal expansion and density must be measured. LFA(Laser Flash Apparatus) has been introduced for measurement of thermal diffusivity. To measure the thermal diffusivity, specimen holder design must be considered to reduce the contact with specimen. So, 3 tip-point holder, so called STD holder in this paper, is recommended. But, in the case of fuel specimen with high burnup, 3 tip-point holder is not available to load specimen in hot-cell. Because it is difficult to load fuel specimen with manipulator as well as ceramic fuel would be broken under irradiation, so we use piece of fuel pellet. To load specimen on holder with safe and use cracked or broken specimen, holder with large periphery contact area is needed even though it makes radial heat loss. In this paper, new specimen holder was made for fuel specimen and compared with STD holder. We observed difference of thermal diffusivity with holders