Thermal Conductivity Measurement of Sintered Vibro-Packed Fuel (4)

Mizuno, Mineo*; Kosaka, Yuji*; Ogawa, Shinta*

JNC TJ8430 2005-002, 136 Pages, 2005/02

JNC-TJ8430-2005-002.pdf:30.86MB

The measurement method of the thermal conductivity has been studied on the sintered UOparticles bed to investigate the necking effects on the thermal conductivity of the Vibro-packed fuel. In the years from 2002 to 2004, the experimental study was carried out in order to survey the sintering condition of UO particles fuel bed, and it was certified that the effective thermal conductivity of the sintered UO2 particles bed could be measured by the apparatus which was constructed based on the Guarded-Comparative Longitudinal Heat Flow Technique. In this work, improvement of the apparatus in order to decrease heat loss from the sample in radial direction in the measurement of the thermal conductivity in high temperature region is carried out. Furthermore, the relation between necking ratio and the thermal conductivity of the sintered ZrO spherical particles bed are surveyed to apply this apparatus to the thermal conductivity measurements of UO spherical particle bed with high sphericity in next stage of study. The results indicate that necking ratio of particles can be controlled easily by the usage of spherical particles, and the relation between necking ratio and sintering strain can be applicable to low necking ratio region. The characteristics of the measurement apparatus are surveyed using quarts glass disc as a standard sample, and the error of the thermal conductivity measurements is estimated 3%(95% confidence limit) in 600~900deg. C , which is smaller than 8% estimated in the measurement of the thermal conductivity carried out in 2002. The thermal conductivity of the sintered ZrO spherical particle bed depends on necking ratio of particles. This result is due to the homogeneity of necking in the particle bed by the usage of spherical particles and the improvement of accuracy of measured thermal conductivity using the advanced apparatus.