Ferrocyanide Safety Project: FY 1991 annual report

Abstract

The Hanford Ferrocyanide Task Team is addressing issues involving ferrocyanide precipitates in the single-shell waste storage tanks (SSTs), in particular the risk of explosion, This Task Team, which is composed of researchers from Westinghouse Hanford Company (WHC), Pacific Northwest Laboratory (PNL), and outside consultants, was formed in response to the need for an updated analysis of safety questions on the Hanford SSTs. The Ferrocyanide Safety Project, discussed in this report, is being conducted by PNL as part of the Waste Tank Safety Program led by WHC. The overall purpose of the WHC program, which is sponsored. by the U.S. Department of Fnerg,c's Tank Safety Project Office, is to provide technical information on ferrocyanide chemistry, and its interaction and reactive behavior with other tank constituents. Ultimately, this information will be used ',o maintain the tanks in a safe condition, implement interim stabilization strategies, and identify optimal disposal options. While by itself ferrocyanide is a stable complex of ferrous ion and cyanide, it can be made to explode in the laboratory in the presence of oxidizing materials such as nitrates and/or nitrites at tempera. tures above 280"C or by sufficient electrical spark. The specific goal of the PNL project i,_to determine the conditions necessary for the ferrocyanide.bearing wastes in Hanford SSTs to represent a hazard, to determine the conditions where these same wastes are not a hazard, or to determine the conditions which are necessary to assure the wastes are safe prior to treatment for permanent disposal. This annual report gives the results of the work conducted by PNL in FW 1991. The activities mainly focused on preparing and characterizing synthetic wastes and alkali nickel ferrocyanides produced using &e In-Farm cesium scavenging flowsheet and Fare potential nickel ferrocyanides thai: could be produced by ali of the cesium scavenging flowsheets.

Ferrocyanide safety project ferrocyanide aging studies. Final report

“…Uncertainties regarding the safety envelope of the Hanford Site ferrocyanide waste tanks led to the declaration of the Ferrocyanide Unreviewed Safety Question (USQ) in October 1990 (Deaton 1990 (Postma et al 1994;Sheridan 1994). The potential for ferrocyanide reactions in Hanford Site SSTs was evaluated, and the energy released during these reactions was quantified (Burger 1984;Burger andScheele 1988, 1991;Cady 1993;Hallen et al 1992; Scheele and Cady 1992; Scheele et al 1991. Dynamic X-ray diffraction (XRD) was also used to identify specific reactions and to quantify reaction rates (Dodds and Thompson 1994).…”

Ferrocyanide safety project ferrocyanide aging studies FY 1995 annual report

“…Uncertainties regarding the safety envelope of the Hanford Site ferrocyanide waste tanks led to the declaration of the ferrocyanide unreviewed safety question (USQ) in October 1990 (Deaton 1990 Numerous studies conducted by the Task Team resulted in closure of the USQ in March 1994. The potential for ferrocyanide reactions in Hanford Site SSTs was evaluated, and the energy released during these reactions was quantified (Burger 1984;Burger andScheele 1988, 1991;Cady 1993;Hallen et al 1992;Scheele and Cady 1992;Scheele et al 1991. Recently, dynamic X-ray diffraction has been used to identify specific reactions and to quantify reaction rates (Dodds and Thompson 1994).…”

Ferrocyanide safety project: Comparison of actual and simulated ferrocyanide waste properties

“…The chemical composition, in particular the ferrocyanide and nitratehitrite content, will determine the maximum reaction rate the mixture will reach if a reaction were to be initiated thermally or by some other unknown mechanism. Experimental studies performed at PNL Hallen et al 1992;Scheele et al 1992a;Scheele et al 1992b;Scheele et al 1992c;Scheele et al 1993) and by Fauske & Associates (Jeppson and Wong 1993) have shown that mixtures of ferrocyanide and the oxidants nitrate and/or nitrite can react rapidly depending on the composition and water content. The work by Scheele et al (1993) investigating the effects of diluents and other potential wastes constituents found that mixtures of sodium nickel ferrocyanide and sodium nitrate and/or nitrite will not explode if sufficient sodium aluminate is present.…”

“…Either the current thermal reactivity and reaction energetics of the wastes should be known, or these storage operating parameters should be based on chemical systems having greater reactivities than the actual wastes. To establish these safe operating parameters, studies have been performed at Los Alamos National Laboratory (LANL) (Scheele and Cady 1989;Cady 1992), at Fauske & Associates (Jeppson and Wong 1993;Postma et al 1994), at Washington State University (Dodds and Thornson, 1994a;1994b) and at PNL Scheele 1988, 1991;Hallen et al 1992;Scheele et al , 1992aScheele et al ,b,c, 1993 to determine the thermal behavior of simulated ferrocyanide wastes and model ferrocyanide and oxidant mixtures, and the energetics of the observed reactions.…”