The performance of Inconel 693 electrodes for processing an iron phosphate glass melt containing 26wt.% of a simulated low activity waste

Iron polyphosphate glasses for waste immobilization

“…The corrosion rates of these alloys in selected iron phosphate melts are comparable to or lower than what has been reported for the borosilicate melt in the JHM at the Savannah River defense waste processing facility. [81][82][83] Inconel 693 was found to have a better corrosion resistance to iron phosphate melts than Inconel 690. Iron phosphate melts possess appropriate viscosity and electrical conductivity for melting in a conventional JHM system.…”

“…and Inconel 693 is a modified version of Inconel 690, with aluminum and niobium additions to improve corrosion resistance. The corrosion rates of these alloys in selected iron phosphate melts are comparable to or lower than what has been reported for the borosilicate melt in the JHM at the Savannah River defense waste processing facility . Inconel 693 was found to have a better corrosion resistance to iron phosphate melts than Inconel 690.…”

“…The VHT corrosion rates were calculated from the time dependence of the depth of penetration of the corrosion product. Department of Energy requirements for ion release rates from borosilicate glass waste-forms for HLWs and low activity wastes (LAWs) are also given and show that that iron phosphate glasses compare favorably, despite in many Day et al, 70 Hsu et al 82,83 Collins-CLT: high cases having waste loadings greater than what is possible for homogeneous borosilicate glasses. Sodium bearing waste (SBW), stored at the Idaho National Laboratory, is an example of an HLW, one with relatively high concentrations of sodium, aluminum, and sulfate.…”

A Review of Iron Phosphate Glasses and Recommendations for Vitrifying Hanford Waste

“…7. The Inconel 693 electrodes used in the research scale JHCM experiments conducted at PNNL to melt (10 days) an iron phosphate glass that contained 26 wt% of AZ102 LAW had a corrosion rate of <2.5 mm/year [Sevigny et al 2011] and ~1.6 mm/year [Hsu et al 2014], two independent measurements. For comparison, the corrosion rate of Inconel 690 that is currently being used in JHCM's at PNNL and in the DWPF at the Savannah River Site has been reported to range between 1.1 and 2.8 mm/year [Barnes et al 1982, Iverson et al 1984.…”

“…No noticeable change or damage was observed in the melter electrodes, or the metal bubbler and melt discharge tubes. The edges of the Inconel 693 electrodes remained sharp after 10 days of operation see section VI, D. Based on the electrode dimensions, as measured from SEM photos, the corrosion rate of the Inconel 693 electrode was <2.5 mm/year [Sevigny et al 2011] and ~1.6 mm/year [Hsu et al 2014], two independent measurements. For comparison, the corrosion rate of the Inconel 690 that is currently used in the DWPF (SRNL) is reported to range between 1.1 and 2.8 mm/year [Barnes et al 1982, Iverson et al 1984.…”