University of Illinois Urbana-Champaign

The effects of contaminant aging and decontamination logistics on remediation after a radiological dispersal event

Hepler, Katherine C

Content Files
HEPLER-DISSERTATION-2020.pdf

Permalink

https://hdl.handle.net/2142/107862

Description

Title
The effects of contaminant aging and decontamination logistics on remediation after a radiological dispersal event
Author(s)
Hepler, Katherine C
Issue Date
2020-03-19
Director of Research (if dissertation) or Advisor (if thesis)
Kaminski, Michael D
Doctoral Committee Chair(s)
Huff, Kathryn D
Committee Member(s)
  • Roy, William R
  • Stubbins, James F
  • Valocchi, Albert
Department of Study
Nuclear, Plasma, & Rad Engr
Discipline
Nuclear, Plasma, Radiolgc Engr
Degree Granting Institution
University of Illinois at Urbana-Champaign
Degree Name
Ph.D.
Degree Level
Dissertation
Date of Ingest
2020-08-26T21:54:08Z
Keyword(s)
  • radiological decontamination
  • washdown operations
Abstract
Rapid remediation of an urban environment after a large-scale nuclear or radiological material release requires simple, non-destructive decontamination techniques with manageable waste. The Integrated Wash-Aid Treatment Emergency Reuse System (IWATERS) was developed for this purpose. In IWATERS, urban surfaces are sprayed, the contaminated wash solution is collected and treated, and the treated wash solution is recycled. This work adds to IWATERS by simulating the logistics of IWATERS and performing experiments that provide insight into optimal IWATERS operating parameters and changes in decontamination efficacy over time. The simulation of material transport and top-level operations of washing down surfaces to remediate four blocks of downtown Chicago, IL identified clay for the treatment of wash solution as the limiting factor in decontamination progress. More importantly, this work created the framework for future simulations of IWATERS deployment to aid recovery optimization. Decontamination experiments showed longer solution application times improve soluble cesium removal and runoff solution can effectively decontaminate larger surfaces. Combined, these results suggest the optimal spray pattern for responders washing down surfaces is spraying along the top portion of buildings for 15 minutes per section and allowing the solution runoff to decontaminate lower portions of buildings. However, the removal of soluble cesium decreases over the first 5 - 10 days following contamination until removals are insignificant (<12%). Changes in the removal efficacy of contaminants that are primarily removed via physical decontamination mechanisms over time, such as inert particles encapsulating radioactivity, were insignificant. Contaminant depth profiles showed that particles did not migrate into the subsurface whereas cesium did. After two months of aging at 65% - 75% average relative humidity with artificial rainfall events, the majority of cesium was found within the first one millimeter of the subsurface. The application of rainfall events after contamination facilitated the migration of cesium into the concrete subsurface. The understanding of decontamination efficacy changes and contaminant-surface interactions as the time between contamination and decontamination increases will aid in recovery planning efforts.
Graduation Semester
2020-05
Type of Resource
Thesis
Permalink
http://hdl.handle.net/2142/107862
Copyright and License Information
Copyright 2020 Katherine Hepler

Owning Collections

Graduate Dissertations and Theses at Illinois PRIMARY
Graduate Theses and Dissertations at Illinois
Dissertations and Theses - Nuclear, Plasma, and Radiological Engineering