Recycle of iodine-loaded silver mordenite by hydrogen reduction

Technical Report · Mon Nov 01 00:00:00 EST 1982

DOI:https://doi.org/10.2172/6595571· OSTI ID:6595571

Burger, L L; Scheele, R D

In 1977 and 1978, workers at Idaho National Engineering Laboratory (INEL) developed and tested a process for the regeneration and reuse of silver mordenite, AgZ, used to trap iodine from the dissolver off-gas stream of a nuclear fuel reprocessing plant. We were requested by the Airborne Waste Management Program Office of the Department of Energy to perform a confirmatory recycle study using repeated loadings at about 150/sup 0/C with elemental iodine, each followed by a drying step at 300/sup 0/C, then by iodine removal using elemental hydrogen at 500/sup 0/C. The results of our study show that AgZ can be recycled. There was considerable difficulty in stripping the iodine at 500/sup 0/C.; however, this step went reasonably well at 550/sup 0/C or slightly higher, with no apparent loss in the iodine-loading capacity of the AgZ. Large releases of elemental iodine occurred during the drying stage and the early part of the stripping stage. Lead zeolite, which was employed in the original design to trap the HI produced, is ineffective in removal of I/sub 2/. The process needs modification to handle the iodine. Severe corrosion of the stainless steel components of the system resulted from the HI-I/sub 2/-H/sub 2/O mixture. Monel or other halogen-resistant materials need to be examined for this application. Because of difficulty with the stripping stage and with corrosion, the experiments were terminated after 12 cycles. Thus, the maximum lifetime (cycles) of recycle AgZ has not been determined. Mechanistic studies of iodine retention by silver zeolites and of the behavior of silver atoms on the reduction stage would be of assistance in optimizing silver mordenite recycle.

• Research Organization: Pacific Northwest National Lab. (PNNL), Richland, WA (United States)
• DOE Contract Number: AC06-76RL01830
• OSTI ID: 6595571
• Report Number(s): PNL-4490; ON: DE83005030
• Country of Publication: United States
• Language: English

Related Subjects

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE WASTES FROM NUCLEAR FACILITIES
37 INORGANIC
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
MORDENITE
RECYCLING
REGENERATION
RADIOACTIVE WASTE PROCESSING
ION EXCHANGE
DRYING
HYDRIODIC ACID
HYDROGEN
IODINE
IODINE 131
OFF-GAS SYSTEMS
SILVER COMPOUNDS
BETA DECAY RADIOISOTOPES
BETA-MINUS DECAY RADIOISOTOPES
DAYS LIVING RADIOISOTOPES
ELEMENTS
HALOGEN COMPOUNDS
HALOGENS
HYDROGEN COMPOUNDS
INORGANIC ACIDS
INORGANIC ION EXCHANGERS
INTERMEDIATE MASS NUCLEI
IODINE COMPOUNDS
IODINE ISOTOPES
ION EXCHANGE MATERIALS
ISOTOPES
MANAGEMENT
MATERIALS
MINERALS
NONMETALS
NUCLEI
ODD-EVEN NUCLEI
PROCESSING
RADIOISOTOPES
SILICATE MINERALS
TRANSITION ELEMENT COMPOUNDS
WASTE MANAGEMENT
WASTE PROCESSING
ZEOLITES
052001* - Nuclear Fuels- Waste Processing
400105 - Separation Procedures