Thermal properties of simulated fuel pin for FBR

The development of simulated fuel pins for an FBR is reviewed from the viewpoint of the thermal properties of the heater element and thermal insulator. The fundamental structure of the simulated fuel pin and the basic equations for heat transfer are presented in the first part. An equation for the ratio of the local electric resistance at the top end of the heater to the average resistance is derived in the second part. An equation for the thermal load distribution is given in the third part together with the experimental results on the axial distributions of electrical resistance and thermal load and the temperature distributions of the heater element, sheath and sodium coolant. The maximum heat flux was 283 W/cm2. As for the thermal insulator, the thermal conductivity and the electric resistance of some insulators are given as functions of temperature. The thermal stress of the heater element is analyzed in the fourth part. In the fifth part, some analysis is made on the realization of a heater with cosine heat flux distribution. (Aoki, K.)