Field measurements of tracer gas transport induced by barometric pumping

This paper reports that vertical gas motions induced by barometric pressure variations can carry contaminated gases through a fractured permeable medium into the atmosphere. Earlier theoretical studies suggest that this atmosphere pumping process is capable of transporting radioactive gases through hundreds of meters of rock in transit times on the order of months, rather than the decades required for molecular diffusion. These expectations are being confirmed by tracer gas experiments currently in progress at the Nevada Test Site. Although this work is being done to ensure the containment of underground nuclear tests, it is also applicable to gas transport from underground waste repositories. Even setting aside the possible importance of radioactive gas transport, these experiments also serve to characterize the large-scale transport properties of a rock mass containing a large number of vertical cooling cracks