Heat transfer between pebbles by taking self-heating of each pebble into consideration

The effective thermal conductivity of pebble bed has been measured by many researchers by means of various measurement techniques. Almost no measurement of effective thermal conductivity has been performed by using self-heating pebbles. In actual blanket, the pebbles are heated by neutron interaction. In that case, the temperature profile in each pebble caused by overall heat flow in the pebble bed, for example linear profile, is overlapped with the individual temperature profile originated from the nuclear heating. The driving force to transfer the heat between contacting pebbles is the temperature gradient near the contact region of both pebbles. In this paper, the effect of temperature profile of each contacting pebble on the heat transfer between pebbles is considered and the contribution of the direct heat conduction to the heat transfer between the pebbles is estimated.