MEASUREMENTS OF RN-220 EMANATION FROM ROCKS

Alpha-particle and gamma-ray measurements are employed to determine th e individual emanation and production rates associated with the thoriu m radioactive series for thirty-seven rock specimens of similar to 200 cm(3) individual volume representing igneous, sedimentary, and metamo rphic types, These results are combined to establish Rn-220 emanating powers for each of these specimens, and a wide range of values is obse rved, The generally large Rn-220 emanation observed for these specimen s strongly indicates that non-tortuous diffusion paths are commonly pr esent in the associated structures, which gives more evidence for the existence of well-connected pore networks at the nanometer level in ma ny of the specimens studied, While the results are qualitatively expla inable, they are not predictable in terms of the current macroscopic o bservables, Since Rn-220 and Rn-222 emanation rates from rock specimen s have previously been found to be comparable in magnitude, the relati vely fast determination of Rn-220 emanation rates described herein (me asurements involving I-h duration) is in reasonable probability indica tive of a comparable Rn-222 emanation rate: The employment of Rn-220 a s a convenient screening tool for potentially high Rn-222 emanation so urces is indicated.