Fast Reactors and Accelerator Driven Systems Knowledge Base

Conference Article: Thorium oxide blanket fabrication for Indian fast breeder test reactor

Abstract

For an effective utilization of Thorium in FBRs, use of fertile blanket of thorium oxide/thorium must be considered. Development of a reliable and economic fabrication technique of this fertile material, thus is an important step in the ultimate goal of utilization of thorium in FBRs. Fabrication and supply of blanket assemblies containing thorium oxide pellets to the requisite quality, for full core of Indian Fast Breeder Test Reactor, is one of the important tasks of Nuclear Fuel Complex at Hyderabad, a unit of the Department of Atomic Energy. Starting with ThO₂-powder obtained by oxalate precipitation and calcination, green pellets are produced through powder metallurgical route. In order to achieve sintered densities more than 94% T.D., addition of Mg in small quantities, during oxalate precipitation stage, have been found quite effective. The effect of compacting pressure, green density and sintering temperature on final sintered density of pellets and percentage of shrinkage have been studied to arrive at the optimum fabrication parameters, to yield high density in pellets requiring minimum amount of grinding. The compactability and sinterability characteristics seem to be affected by long storage of powder. Ball milling of powder before pre-compaction and granulation almost restore the original characteristics of the powder. The paper deals with the Indian experience on fabrication of thoria pellets for the Fast Breeder Test Reactor, with some emphasis on the work carried out for standardization of the parameters, quality characteristics of the pellets and on blanket assemblies made. Performance test of these assemblies under actual operating conditions of FBTR, followed by reprocessing studies, will be of great value for the Indian programme of utilization of thorium in the envisaged FBR's.

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Reference:

Proceedings of a technical committee meeting on utilization of thorium-based nuclear fuel: current status and perspectives held in Vienna, 2-4 December 1985

International Atomic Energy Agency, Vienna (Austria)

IAEA-TECDOC--412, pp:73-88