## 3 Results and Discussion
### Circuit Walking Path Results
#### 3.3.2 Resuspension during Circuit Walking  
A filter sample was deployed near the edge of the transition area (from Sr-85 contaminated sand surface to uncontaminated loose sand area) for each walking experiment on the sand walking path to monitor the spread of Sr-85 contaminated particles adjacent to the contaminated area. During the experiments, there were no visible particles transferred (kicked or dragged, etc.) over to the filter, and the measurements for each experiment were extremely close to the background measurements. The NSC sample produced a non-detect  
Figure 16: Percent Residual of Sr-85 Contaminated Particles from Foot Traffic Experiments.  
\begin{table}
\begin{tabular}{c c c c c} \hline
**Surfaces** & **Stab. Tech.** & **CaCl\({}_{2}\)** & **MVP-Fx** & **Soil\({}_{2}\)O** \\ \hline \multirow{3}{*}{Asphalt} & Control & 0.1143 & \textless{}0.0001 & 0.0004 \\ \cline{2-5}  & CaCl\({}_{2}\) & & 0.0481 & 0.1662 \\ \cline{2-5}  & MVP-Fx & & & 0.0023 \\ \hline \multirow{3}{*}{Concrete} & Control & 0.0120 & 0.0553 & 0.1460 \\ \cline{2-5}  & CaCl\({}_{2}\) & & 0.0799 & 0.0157 \\ \cline{1-1} \cline{2-5}  & MVP-Fx & & & 0.1769 \\ \hline \end{tabular}
\end{table}
Table 11: Statistical results (_p_-values) for foot traffic experiments percent residual. Gray shading indicates a significant difference (_p_ < 0.05).  
result, while each stabilization technology experiment produced less than 4 counts per second (cps), indicating a minimal presence of radiological material.  
For the air sampler (5 cfm flow) set up approximately 30 cm above the ground near the contaminated area to collect an air sample for each sand walking path experiment, radiological activity was detected only from the air samples collected during the NSC experiment (\(2.8\times 10^{-10}\) uCi/mL) and the Soil2O stabilization technology (9.7 \(\times\) 10\({}^{-11}\) uCi/mL). These values are two to three orders of magnitude less than the derived air concentration (DAC) value (6 \(\times\) 10\({}^{-7}\) uCi/mL for Sr-85 particles potentially retained for years after exposure) listed in the US regulations for standards for radiation protection [19]. The DAC is defined as the concentration of a given radionuclide in the air which, if breathed for a working year of 2000 h under conditions of light work (1.2 cubic meters of air per hour), results in an intake of one annual limit on intake. The DAC values are presented for information only because they are intended to control chronic occupational exposure and are calculated based on a semi-infinite cloud of uniform concentration. This is not necessarily the exposure these experiments are intended to simulate, so the relationship between DAC and the experimental results may differ in an actual incident.  
Particles containing approximately 80 uCi were placed on the surface prior to the walking experiment. For the NSC experiment, approximately 2 \(\times\) 10\({}^{-4}\) uCi was measured on the air sample, and for the Soil2O experiment, approximately 7 \(\times\) 10\({}^{-5}\) uCi was measured on the air sample. The ratio of measured activity in the air to the activity available on the ground was 2.5 \(\times\) 10\({}^{-6}\) and 9 \(\times\) 10\({}^{-7}\) for the NSC and Soil2O experiments, respectively. Albeit slight, the Soil2O experiments indicated a decreased availability of particles for inhalation. Neither air sample collected during the CaCl2 and Phos-Chek MVP-Fx experiments generated detectable radiological activity, indicating they also functioned to decrease the availability of particles. During each simulated vehicle and foot traffic experiments (and all the experimental preparatory work, including particle contamination), two air samples (3 cfm flow) were collected in the general work area of the containment tent. The average concentration of these samples was 4.9 \(\times\) 10\({}^{-13}\) uCi/mL, approximately six orders of magnitude less than the DAC.