Separation of Nuclear Fuel Surrogates from Silicon Carbide Inert Matrix

Abstract

Project End Date: September 12, 2008 (with a six mo. no cost extension) Research ObjectivesThe objective of this project has been to identify a process for separating transuranic species from silicon carbide (SiC). Silicon carbide has become one of the prime candidates for the matrix in inert matrix fuels ,(IMF) being designed to reduce plutonium inventories and the long halflives actinides through transmutation Since complete reaction is not practical it become necessary to separate the non-transmuted materials from the silicon carbide matrix for ultimate reprocessing. This work reports a method for that required process.An efficient process has been developed for separating transuranic species from a silicon carbide (SiC) matrix. At high temperature (above 850 ºC) SiC can be oxidized in molten alkali salt such as sodium carbonate (Na 2 CO 3 ) and potassium carbonate (K 2 CO 3 ) and form water soluble products such as sodium or potassium silicate. SiC fine powder (1micron) was totally dissolved in Na 2 CO 3 molten salt after 30 min heat treatment at 900 ºC. SiC pellets were completely dissolved in K 2 CO 3 molten salt after approximate 40 hours heat treatment at 1050 ºC. Separation was achieved by dissolving the products obtained from SiC corrosion in water. Ceria (CeO 2 ) remained unchanged and was not corroded in these molten salt environments.