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Title:Characterization of pressurized wash for decontamination of porous building materials and a Goldsim model for recycling contaminated wash
Author(s):Hepler, Katherine C
Advisor(s):Kaminski, Michael D.
Contributor(s):Roy, William
Department / Program:Nuclear, Plasma, & Rad Engr
Discipline:Nuclear, Plasma, Radiolgc Engr
Degree Granting Institution:University of Illinois at Urbana-Champaign
Subject(s):Radiological contamination
Pressurized wash
Abstract:The probability of a terrorist attack with a Radiological Dispersion Device (RDD) is unknown, response and recovery plans must be created beforehand to minimize the detrimental economic, social, and psychological effects of wide-spread nuclear contamination. In 2014 the IWATERS system was proposed for quick, non-destructive remediation of the urban environment. An ionic wash solution (“Wash Aid”) is applied by hosing and then used wash solution is recycled on-site with sand-clay beds. The following experiments were performed to help characterize the IWATERS technology. The HUDEX (High-pressure Urban Decontamination EXperiments) system applied a pressurized wash solution with a 40° nozzle to Sr-85, Cs-137, and Eu-152 contaminated brick, asphalt, and concrete. Statistically significant increases in percent removals were observed using a nominal 0.5 M KCl solution vs. tap water (20-40% difference for majority). Highest decontamination was 84.6% Sr from asphalt with 0.5 M KCl. Tests varying cleaning rate and distance on concrete with tap water yielded insignificant trends (8%-45% average removals). Depth profiles of the remaining contamination were determined after cleaning from the 15-cm distance. By using sand paper to remove layers from the coupon, the relative fraction activity removed in each layer was plotted vs. depth. Consistently, Cs and Sr penetrated significantly deeper than Eu, with Sr penetrating slightly more than Cs. Relatively small grind layers (17 to 35 μm vs. 1 to 7 mm) made literature comparison difficult. More tests are needed to determine effects of pressurized washing on contamination depth profiles. A GoldSim Contaminant Transport model for recycling contaminated wash solution through a sand/clay column was modified for sensitivity analyses of column and material parameters. Linear or quadratic relationships (R2 ≥ 0.98) were observed between most column parameters and breakthrough time and total volume of wash solution processed. Using the relationships, look-up tables for first responders and equations for on-the-fly modifications can be generated. Changes to the sand/clay bed composition yielded mostly non-linear trends for both total volume recycled and elution time. Therefore, in a response scenario, the composition must be set beforehand. Parameters such as bed area and head height are more easily changed to total recycled wash solution and recycling rate.
Issue Date:2017-07-20
Rights Information:Copyright 2017 Katherine Hepler
Date Available in IDEALS:2017-09-29
Date Deposited:2017-08

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