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Dry Deactivation of Sodium Metal in a Molten LiCl-KCl-CsCl-NaCl System

Journal Article · · Journal of Hazardous, Toxic, and Radioactive Waste

A three-fold experimental study was performed to investigate and characterize a dry technique for deactivation of sodium metal in a molten salt system. First, proof-of-principle testing of this technique at bench-scale was performed. This involved loading and melting tens of grams of sodium metal atop a pool of LiCl-KCl-CsCl eutectic at ~300°C to which ammonium chloride particles were added while mixing. The ammonium chloride reacted with sodium to form sodium chloride and nitrogen/hydrogen off-gases. The sodium chloride assimilated into the salt pool, forming a quaternary salt mixture of LiCl-KCl-CsCl-NaCl. Second, characterization of a LiCl-KCl-CsCl-NaCl system using differential scanning calorimetry was performed to produce a partial phase diagram of LiCl-KCl-CsCl eutectic versus NaCl and identify a practical extent of NaCl loading into LiCl-KCl-CsCl. Third, the dry deactivation technique was demonstrated at kg-scale with sodium metal that was separated from uranium metal in unirradiated blanket elements for the Fermi-1 nuclear reactor. The quaternary salt product from the demonstration was sampled and shown to be devoid of sodium metal. In short, this study qualified a technique to deactivate sodium metal in the absence of air or water. Specifically, it provides a method to deactivate sodium metal from radiological systems in dry environments, including radiologically shielded enclosures, where the absence of air and moisture is necessary. While this study focused on the deactivation of sodium metal, including bond sodium from unirradiated blanket elements, the technique could also be applied to other alkali metals, including lithium, sodium, potassium, rubidium, cesium, and mixtures thereof.

Research Organization:
Idaho National Laboratory (INL), Idaho Falls, ID (United States)
Sponsoring Organization:
USDOE Office of Nuclear Energy (NE); USDOE Office of Environmental Management (EM)
Grant/Contract Number:
AC07-05ID14517
OSTI ID:
3012996
Report Number(s):
INL/JOU-24-81132
Journal Information:
Journal of Hazardous, Toxic, and Radioactive Waste, Journal Name: Journal of Hazardous, Toxic, and Radioactive Waste Journal Issue: 4 Vol. 29
Country of Publication:
United States
Language:
English