Study on hydrogen evolution during treatment of SRS high level radioactive sludge simulant with formic acid
At the Savannah River Site, the Defense Waste Processing Facility (DWPF) was constructed to vitrify high-level radioactive liquid waste in borosilicate glass for permanent storage. Formic acid, which serves as both an acid and a reducing agent, is used to treat the washed alkaline sludge during melter feed preparation primarily to improve the processability of the feed and to reduce mercury to a metallic state for steam stripping. The high-level sludge is composed of many transition metal hydroxides. Among them there are small quantities of platinum group metals such as Ru, Rh and Pd that are fission products. During the treatment of simulated sludge with formic acid, significant amounts of hydrogen were generated when the platinum group metals were included in the sludge. Apparently the noble metals in the sludge were reduced to metallic states and caused formic acid to decompose catalytically into hydrogen and carbon dioxide, usually with an induction period. A parametric study revealed the following: increasing the amount of formic acid added to the sludge increased the hydrogen generation rate dramatically; once the catalysts were activated, the hydrogen generation rate decreased significantly with a lowering of the temperature of the sludge; the relative catalytic activities of the noble metals in the sludge decreased in the following order: Rh > Ru >> Pd; ammonium ions were generated catalytically from the reaction between formic acid and nitrate; when present, the noble metals caused higher upward drifts of the sludge pH.
- Research Organization:
- Westinghouse Savannah River Co., Aiken, SC (United States)
- Sponsoring Organization:
- USDOE, Washington, DC (United States)
- DOE Contract Number:
- AC09-89SR18035
- OSTI ID:
- 10112324
- Report Number(s):
- WSRC-MS-92-270; CONF-920808-13; ON: DE93003185
- Resource Relation:
- Conference: American Institute of Chemical Engineers (AIChE) summer national meeting,Minneapolis, MN (United States),9-12 Aug 1992; Other Information: PBD: [1992]
- Country of Publication:
- United States
- Language:
- English
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Treatment of simulated high-level radioactive waste with formic acid: Bench-scale study on hydrogen evolution
IMPACT OF NOBLE METALS AND MERCURY ON HYDROGEN GENERATION DURING HIGH LEVEL WASTE PRETREATMENT AT THE SAVANNAH RIVER SITE
Related Subjects
HIGH-LEVEL RADIOACTIVE WASTES
UNDERGROUND DISPOSAL
FORMIC ACID
DECOMPOSITION
HYDROGEN
MONITORING
SAVANNAH RIVER PLANT
SLUDGES
VITRIFICATION
BOROSILICATE GLASS
CATALYSIS
052001
052002
WASTE PROCESSING
WASTE DISPOSAL AND STORAGE