Estimates of Acetonitrile Generation from Scale Melter Testing of LAW Simulants (VSL-19S4573-1, Rev A)

Technical Report · Sat Oct 19 04:00:00 EDT 2019

DOI:https://doi.org/10.2172/1844981· OSTI ID:1844981

Matlack, Keith S. ^[1]; Pegg, Ian L. ^[1]

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1. The Catholic Univ. of America, Washington, DC (United States)

With high nitrate feeds, such as Hanford low activity waste (LAW) feeds, the addition of reductants is necessary in order to control foaming of the molten glass pool in the melter because such foaming can lead to extensive downtime. Sugar, which was used for this purpose at the West Valley Demonstration Project vitrification facility, has been selected as the baseline reductant for the Hanford Waste Treatment and Immobilization Plant (WTP). The amount of sugar required increases with the amount of nitrates present in the feed and decreases with the amount of waste organics present in the feed, which themselves act as reductants. Excessive additions of reductants can be deleterious, leading to over-reduction of the melt and formation of sulfides and molten metals. Consequently, the oxidants and reductants in the feed must be suitably balanced. The basis for achieving this balance was developed by VSL and Atkins for the vitrification of high-sodium-nitrate feeds at Savannah River's M-Area and has been successfully applied to the processing of a wide variety of simulated WTP feeds over many years and was ultimately incorporated into the WTP process control models. The reaction of sugar with nitrates and nitrites in the cold cap controls the redox state of the underlying melt, which prevents foaming, and also significantly decreases the amount of NOx produced. In addition, however, small amount of organics reaction products are formed. Extensive testing at VSL over the past more than 20 years has shown that acetonitrile is the most prevalent such organic species. That testing has also shown that a significant amount of acetonitrile is captured in the liquid scrubbers in the WTP off-gas treatment system and will therefore be present in the secondary liquid effluents. In particular, acetonitrile is prevalent in the submerged bed scrubber (SBS) and wet electrostatic precipitator (WESP) liquid effluents from WTP LAW off-gas treatment. When these liquids are concentrated in the WTP Effluent Management Facility (EMF) evaporator in the direct feed LAW (DFLAW) flow-sheet, VSL testing has shown that the majority of the acetonitrile partitions to the evaporator condensate. Since the evaporator condensate is directed to the Hanford Effluent Treatment Facility (ETF), this creates a potential issue with the ETF waste acceptance criteria. Consequently, there is a need to assess the available test data in order to develop projections of the likely concentrations of acetonitrile in the streams to ETF. The objective of the present report is to provide such an assessment in order to provide input to flow-sheet model projections.

• Research Organization: Hanford Site (HNF), Richland, WA (United States); USDOE Office of River Protection (ORP), Richland, WA (United States)
• Sponsoring Organization: USDOE Office of Environmental Management (EM)
• DOE Contract Number: AC27-01RV14136
• OSTI ID: 1844981
• Report Number(s): ORP-67600-00
• Country of Publication: United States
• Language: English

Related Subjects

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE WASTES FROM NUCLEAR FACILITIES