The Effects of Contaminant Aging and Decontamination Logistics on Remediation after a Radiological Dispersal Event
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.
