Dissolution of Irradiated Nuclear Fuel from the Big Rock Point Reactor

Abstract

The Advanced Fuel Cycle Initiative (AFCI), funded by the Department of Energy, is developing proliferation-resistant technologies that allow safe and economical disposal of waste from reactors. A critical element is the separation of key radionuclides followed by either waste disposal, or conversion of long-lived isotopes to reactor fuel. A sample of Big Rock Point uranium oxide fuel was dissolved in nitric acid at elevated temperature to provide feedstock for the UREX+ demonstration. Elevated temperature led to the complete dissolution of noble metals at relatively low nitric acid concentrations. The conditions used in this study are not suitable for plant-scale application. Three products were obtained: (1) a dissolved fuel solution, (2) undissolved residue, and (3) leached cladding containing no observable undissolved fuel. Elemental analyses of the dissolved fuel, residue, and leached cladding are presented. The data show that 99% of the fuel, including the noble metals was dissolved. The small amount of residue contained primarily Zr, Mo, and Pu. While the total amount of residue is small, approximately 20% of the total Pu was found in the residue. Several proposals are made for the prevention of precipitation of the residue.