ABSTRACT
The Idaho Nuclear Technology Engineering Center (INTEC) (formerly called Idaho Chemical Processing Plant, ICPP) at the Idaho National Engineering and Environmental Laboratory (INEEL) processed spent nuclear fuels for the separation and recovery of uranium from 1953 until 1992. They were primarily fuels of highly enriched uranium. The two major categories processed were Zircaloy fuels from naval reactor cores and aluminum fuels from the Advanced Test Reactor and other test reactors at the INEEL and throughout the world. A variety of other types were also processed, such as stainless steel fuels from the EBR-II reactor and graphite Rover fuel, in which uranium carbide spheres coated with pyrolytic carbon were dispersed in a graphite matrix; the particles also contained niobium carbide. The Zircaloy fuels were dissolved in hydrofluoric acid (HF) and, after complexing the excess HF with aluminum nitrate, nitric acid was added. The aluminum fuels were dissolved in nitric acid, catalyzed by mercuric nitrate. One tankful (1×L) of acid-deficient waste was generated from nitric acid-mercuric ion catalyzed dissolution of uranium-aluminum fuel with ammonium hydroxide used to provide the acid deficiency and the salting strength for solvent extraction of the uranium. The stainless steel fuels were either dissolved in sulfuric acid or electrolytically in nitric acid. Rover fuels were processed by burning the graphite in fluidized-bed burners. Then the residual ash from the fuel particles, in which the uranium and niobium carbides had been converted to oxides, were dissolved in nitric and hydrofluoric acids, after which excess fluoride was complexed with aluminum nitrate.
