Figure 8
From: Gas transport across the low-permeability containment zone of an underground nuclear explosion
Comparison of the best-fit single-fracture barometric transport model with actual soil gas observations at SGZ provided by an LLNL tarp-and-sample system. The first 10 daily samples did not produce detections (open red squares), while the last 4 daily samples were detections (filled green squares). The concentration history simulation (blue line) essentially matches both the first arrival of the Freon and the subsequent concentration levels measured during 4 consecutive days. Note that time (horizontal axis) is measured from the start of simulation (vertical arrow) which began about a week before the actual Freon tracer injection to initialize the simulation. The 3.6-hour Freon injection ended on 18 February 2018 (vertical mark on time axis) between 7 and 8 days after the start of the simulation. Time elapsed between Freon injection and its apparent arrival at the surface is approximately 24.3 days.
