Nitric-glycolic flowsheet reduction/oxidation (redox) model for the defense waste processing facility (DWPF)
- Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL)
Control of the REDuction/OXidation (REDOX) state of glasses containing high concentrations of transition metals, such as High Level Waste (HLW) glasses, is critical in order to eliminate processing difficulties caused by overly reduced or overly oxidized melts. Operation of a HLW melter at Fe+2/ΣFe ratios of between 0.09 and 0.33, retains radionuclides in the melt and thus the final glass. Specifically, long-lived radioactive 99Tc species are less volatile in the reduced Tc4+ state as TcO2 than as NaTcO4 or Tc2O7, and ruthenium radionuclides in the reduced Ru4+ state are insoluble RuO2 in the melt which are not as volatile as NaRuO4 where the Ru is in the +7 oxidation state. Similarly, hazardous volatile Cr6+ occurs in oxidized melt pools as Na2CrO4 or Na2Cr2O7, while the Cr+3 state is less volatile and remains in the melt as NaCrO2 or precipitates as chrome rich spinels. The melter REDOX control balances the oxidants and reductants from the feed and from processing additives such as antifoam.
- Research Organization:
- Savannah River Site (SRS), Aiken, SC (United States)
- Sponsoring Organization:
- USDOE
- DOE Contract Number:
- AC09-08SR22470; AC09-76SR00001; AC09-96SR18500
- OSTI ID:
- 1373537
- Report Number(s):
- SRNL-STI-2017-00005; TRN: US1800532
- Country of Publication:
- United States
- Language:
- English
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