FY 1993 Ferrocyanide Tank Safety Project: Effects of Aging on Ferrocyanide Wastes test plan for the remainder of FY 1993.

摘要

Researchers in the Hanford Ferrocyanide Task Team are studying safety issues associated with ferrocyanide precipitates in single shell waste storage tanks (SST). Ferrocyanide is a stable complex of ferrous, ion and cyanide ion that is considered nontoxic because it does not dissociate readily in aqueous solutions. However, in the laboratory at temperatures in excess of 180(degrees)C and in the presence of oxidizers such as nitrates and nitrites, dry ferrocyanide and ferrocyanide waste stimulants can be made to react exothermically. The Ferrocyanide Safety Project at the Pacific Northwest Laboratory (PNL) is part of the Waste Tank Safety Program at Westinghouse Hanford Company (WHC). The purpose of the WHC program is to (1) maintain the ferrocyanide tanks with minimal risk of an accident, (2) select one or more strategies to assure safe storage, and (3) close out the unreviewed safety question (USQ). Tank ferrocyanide wastes were exposed to highly alkaline wastes from subsequent processing operations. Chemical reactions with caustic may have changed the ferrocyanide materials during 40 years of storage in the SSTs. Research in the (open quotes)Effects of Aging on Ferrocyanide Wastes(close quotes) task is targeted at studying aging of ferrocyanide tank simulants and other ferrocyanide materials to obtain a better understanding of how tank materials may have changed over the years. The research objective in this project is to determine the solubility and hydrolysis characteristics of simulated ferrocyanide tank wastes in alkaline media. The behavior of ferrocyanide simulant wastes is being determined by performing chemical reactions under conditions that might mimic the potential ranges in SST environments. Experiments are conducted at high pH, at high ionic strength, and in the presence of gamma radiation. Verification of simulant study findings by comparison with results with actual waste will also be required. (ERA citation 18:025751)