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Title: Investigation of Sorption and Diffusion Mechanisms, and Preliminary Economic Analysis

Technical Report ·
DOI:https://doi.org/10.2172/1343542· OSTI ID:1343542
 [1];  [1];  [1];  [2]
  1. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
  2. Georgia Inst. of Technology, Atlanta, GA (United States)

This report describes the synthesis and evaluation of molecular sieve zeolite membranes to separate and concentrate tritiated water (HTO) from dilute HTO-bearing aqueous streams. Several monovalent and divalent cation exchanged silico alumino phosphate (SAPO-34) molecular sieve zeolite membranes were synthesized on disk supports and characterized with gas and vapor permeation measurements. The pervaporation process performance was evaluated for the separation and concentration of tritiated water. Experiments were performed using tritiated water feed solution containing tritium at the high end of the range (1 mCi/mL) anticipated in a nuclear fuel processing system that includes both acid and water streams recycling. The tritium concentration was about 0.1 ppm. The permeate was recovered under vacuum. The HTO/H2O selectivity and separation factor calculated from the measured tritium concentrations ranged from 0.99 to 1.23, and 0.83-0.98, respectively. Although the membrane performance for HTO separation was lower than expected, several encouraging observations including molecular sieving and high vapor permeance are reported. Additionally, several new approaches are proposed, such as tuning the sorption and diffusion properties offered by small pore LTA zeolite materials, and cation exchanged aluminosilicates with high metal loading. It is hypothesized that substantially improved preferential transport of tritium (HTO) resulting in a more concentrated permeate can be achieved. Preliminary economic analysis for the membrane-based process to concentrate tritiated water is also discussed.

Research Organization:
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Sponsoring Organization:
USDOE Office of Nuclear Energy (NE)
DOE Contract Number:
AC05-00OR22725
OSTI ID:
1343542
Report Number(s):
ORNL/TM-2017/59; AF5805010; NEAF327
Country of Publication:
United States
Language:
English