Measurement of the emanation of radon-222 from Danish soils

The radon-222 emanation from 70 samples of Danish soils, subsoils, and sedimentary rocks has been measured. Two methods have been employed. The first one is to follow the growth of the radon concentration in a radon-tight sample container by transferring small air samples to a scintillation flask detection system. The second one is to measure the equilibrium gamma-activities of lead-214 and bismuth-214 in the sample when the sample container is open and, subsequently, when it is closed. Based on the measured emanation rates the samples are grouped in three classes: 1) less than 5 atoms . sec-1 . kg-1, 2) from 5 to 10 atoms . sec-1 . kg-1, and 3) more than 10 atoms . sec-1 . kg-1. In class 3) some diatomitic clays have shown emanation rates as large as 100 atoms . sec-1 . kg-1.