Thorium utilization in a pebble bed reactor

Thorium reserves in the earth's crust are much more than those of uranium, which today measure about 1.5 million tonnes of reasonably assured resources, plus 3 million tonnes of estimated additional resources. These large amount of thorium reserves, also available in Turkey encourages to focus on the utilization of thorium. The most remarkable applications of the use of thorium have been in high temperature reactors. The high temperature pebble bed reactor, which has been chosen as the basis for this study, is a close approximation of the thorium utilizing German reactor THTR. Pebble bed reactors have some unique features which are suitable to burn thorium. (i) The fuel is loaded in the form of coated particles, which are embedded in the graphite matrix of the fuel pebbles, allowing exceptionally high heavy metal burnups; and (ii) the continuous (on-line) fuel loading allows a high utilization factor. The criticality search of the pebble bed reactor is computed by the use of the SCALE4.4 code, CSASIX and KENOVa modules. And the in-core fuel management is computed via SCALE4.4 code, ORIGEN-S module