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Title: Implementation of flowsheet change to minimize hydrogen and ammonia generation during chemical processing of high level waste in the Defense Waste Processing Facility

Testing was completed to develop a chemical processing flowsheet for the Defense Waste Processing Facility (DWPF), designed to vitrify and stabilize high level radioactive waste. DWPF processing uses a reducing acid (formic acid) and an oxidizing acid (nitric acid) to rheologically thin the slurry and complete the necessary acid base and reduction reactions (primarily mercury and manganese). Formic acid reduces mercuric oxide to elemental mercury, allowing the mercury to be removed during the boiling phase of processing through steam stripping. In runs with active catalysts, formic acid can decompose to hydrogen and nitrate can be reduced to ammonia, both flammable gases, due to rhodium and ruthenium catalysis. Replacement of formic acid with glycolic acid eliminates the generation of rhodium- and ruthenium-catalyzed hydrogen and ammonia. In addition, mercury reduction is still effective with glycolic acid. Hydrogen, ammonia and mercury are discussed in the body of the report. Ten abbreviated tests were completed to develop the operating window for implementation of the flowsheet and determine the impact of changes in acid stoichiometry and the blend of nitric and glycolic acid as it impacts various processing variables over a wide processing region. Three full-length 4-L lab-scale simulations demonstrated the viability of the flowsheetmore » under planned operating conditions. The flowsheet is planned for implementation in early 2017.« less
Authors:
 [1] ;  [1] ;  [1] ;  [1] ;  [2] ;  [3]
  1. Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL)
  2. Auburn Univ., AL (United States)
  3. Univ.of South Carolina, Columbia, SC (United States)
Publication Date:
OSTI Identifier:
1327781
Report Number(s):
SRNL-STI--2016-00554
TRN: US1700315
DOE Contract Number:
AC09-08SR22470
Resource Type:
Technical Report
Research Org:
Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL)
Sponsoring Org:
USDOE Office of Environmental Management (EM)
Country of Publication:
United States
Language:
English
Subject:
12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE WASTES FROM NUCLEAR FACILITIES; STEAM STRIPPING; HIGH-LEVEL RADIOACTIVE WASTES; FORMIC ACID; AMMONIA; GLYCOLIC ACID; FLOWSHEETS; HYDROGEN; MERCURY; IMPLEMENTATION; MODIFICATIONS; NITRIC ACID; REDUCTION; SLURRIES; NITRATES; SIMULATION; STOICHIOMETRY; TESTING; FEASIBILITY STUDIES; MINIMIZATION; RADIOACTIVE WASTE PROCESSING