Hydrofluoric acid dissolution of spent radioactive and hazardous HEPA filters
This document discusses a process that treats High Efficiency Particulate Air (HEPA) filters contaminated with radioactive particles containing transuranic and hazardous elements which has been studied at the Idaho Chemical Processing Plant (ICPP). This process uses three to four steps to spent HEPA filter so that they meet regulatory requirements for disposal. The first step of the process is to bake the spent HEPA filters at 550{degrees}C for 3 hours to volatilize organic binder which is used to provide strength in the filter's silicon glass media. In the second step, the filters are first leached in nitric acid, then are dissolved in hydrofluoric acid. The dissolution is conducted using an optimum fluoride to silicone molar ratio of 7/1 to prevent: (1) excess unreacted HF (free HF), (2) the formation of insoluble fluoride salts, and (3) the need of excessive aluminum nitrate to complex the free HF. Finally, the free HF is complexed with aluminum nitrate to an (HF) between 0.020 and 0.04 molar. The resulting solution from this process is minimally corrosive to stainless steel and is a stable high-level liquid waste that can be converted to a high-level solid waste in a fluidized bed operated at 500{degrees}C. The stainless steel HEPA filter housing, which is not dissolved during the dissolution step, is compacted and disposed of as a nonhazardous, low-level radioactive waste.
- Research Organization:
- Westinghouse Idaho Nuclear Co., Inc., Idaho Falls, ID (United States)
- Sponsoring Organization:
- DOE; USDOE, Washington, DC (United States)
- DOE Contract Number:
- AC07-84ID12435
- OSTI ID:
- 5041573
- Report Number(s):
- WINCO-11814; CONF-920851--49; ON: DE92017267
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE WASTES FROM NUCLEAR FACILITIES
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400201 -- Chemical & Physicochemical Properties
ALPHA-BEARING WASTES
BAKING
CALCINATION
CHEMICAL REACTION KINETICS
CHEMICAL REACTIONS
DECOMPOSITION
DISSOLUTION
ELECTRODES
ELEMENTS
FILTERS
FLUORINE COMPOUNDS
FUEL REPROCESSING PLANTS
HALOGEN COMPOUNDS
HAZARDOUS MATERIALS
HEATING
HYDROFLUORIC ACID
HYDROGEN COMPOUNDS
IDAHO CHEMICAL PROCESSING PLANT
INORGANIC ACIDS
KINETICS
LEACHING
MATERIALS
METALS
NATIONAL ORGANIZATIONS
NUCLEAR FACILITIES
OFF-GAS SYSTEMS
PYROLYSIS
RADIOACTIVE MATERIALS
RADIOACTIVE WASTES
REACTION KINETICS
SEPARATION PROCESSES
THERMOCHEMICAL PROCESSES
TITANIUM
TRANSITION ELEMENTS
US AEC
US DOE
US ERDA
US ORGANIZATIONS
WASTES