Nitric Acid Cleaning Of A Sodalite–sodium Diuranate Scale In High Level-waste Evaporators#

Abstract

The operation of a high-level radioactive waste evaporator was curtailed due to the presence of an aluminosilicate scale that contained sodium diuranate with a uranium-235 enrichment of approximately 3%. Utilizing pervious work, a plan to clean the evaporator system using a heated nitric acid and depleted uranium mixture was developed that addressed numerous safety issues. The sodium aluminosilicate scale was successfully removed during two cleaning cycles, but soluble silicon was not present in measurable quantities in the liquid samples taken during cleaning. Although this phenomenon was not observed in the laboratory tests, silicon was detected in a loose, solid phase discovered in the evaporator cone after the first cleaning cycle. #This report was prepared by Westinghouse Savannah River Company (WSRC) for the United States Department of Energy under Contract No. DE-AC09-88SR18035 and is an account of work performed under that contract. Accordingly, the U.S. Government retains a non-exclusive, royalty-free license to publish or reproduce the published form of this contribution, or allow others to do so, for U.S. Government purposes. Neither the United States Department of Energy, nor WSRC, nor any of their employees makes any warranty, expressed or implied, or assumes any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, or product or process, disclosed herein or represents that its use will not infringe privately owned rights. Reference herein to any specific commercial product, process, or service by trademark, name, manufacturer, or otherwise does not necessarily constitute or imply endorsement, recommendation, or favoring of same by WSRC or the United States Government or any agency thereof. The views and opinions of the authors expressed herein do not necessarily state or reflect those of the United States Government or any agency thereof.