TREATABILITY STUDIES USED TO TEST FOR EXOTHERMIC REACTIONS OF PLUTONIUM DECONTAMINATION CHEMICALS
Fluor Hanford is decommissioning the Plutonium Finishing Plant (PFP) at the Hanford site in Eastern Washington. Aggressive chemicals are commonly used to remove transuranic contaminants from process equipment to allow disposal as low level waste. Chemicals being considered for decontamination of gloveboxes in PFP include cerium(IV) nitrate in a nitric acid solution, and proprietary commercial solutions that include acids, degreasers, and sequestering agents. Fluor's decontamination procedure involves application of chemical solutions as a spray on the contaminated surfaces, followed by a wipe-down with rags. This process effectively transfers the transuranic materials to the decontamination liquids, which are then absorbed by rags and packaged for disposal as TRU waste. Concerns regarding the safety of this procedure developed following a fire at Rocky Flats in 2003. The fire occurred in a glovebox that had been treated with cerium nitrate, which is one of the decontamination chemicals that Fluor Hanford has proposed to use. The investigation of the event was hampered by the copious use of chemicals and water to extinguish the fire, and was not conclusive regarding the cause. However, the reviewers noted that rags were found in the glovebox, suggesting that the combination of rags and chemicals may have contributed to the fire. With that uncertainty, Fluor began an investigation into the potential for fire when using the chemicals and materials in the decontamination process. The focus of this work has been to develop a disposal strategy that will provide a chemically stable waste form at expected Hanford waste storage temperatures. Treatability tests under CERCLA were used to assess the use of certain chemicals and wipes during the decontamination process. Chemicals being considered for decontamination of gloveboxes at PFP include cerium (IV) nitrate in a nitric acid solution, and proprietary commercial solutions as RadPro{trademark} that include acids, degreasers, and sequestering agents. As part of the treatability study, Fluor and the Pacific Northwest National Laboratory (PNNL) personnel have evaluated the potential for self-heating and exothermic reactions in the residual decontamination materials. Exothermic reactions that release significant heat and off-gas have been discovered for both the cerium nitrate, as seen in a fire at Rocky Flats, and proprietary solutions developed for decontamination purposes. From the treatability studies, certain limiting conditions have been defined that will aid in assuring safe operations and waste packaging during the decommissioning process.
- Research Organization:
- Fluor Hanford, Richland, WA (United States)
- Sponsoring Organization:
- ENVIRONMENTAL MANAGEMENT (US)
- DOE Contract Number:
- AC06-96RL13200
- OSTI ID:
- 840800
- Report Number(s):
- HNF-25630-FP, Rev.0; TRN: US0502175
- Resource Relation:
- Conference: Conference title not supplied, Conference location not supplied, Conference dates not supplied; Other Information: PBD: 6 Jun 2005
- Country of Publication:
- United States
- Language:
- English
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