| In an earlier post, I requested info on neutron activation of gravel under-floors. Thanks for the replies. We have excavated under the concrete floor, and found activity similar to that in the floor. The underfloor turned out to be a mixture of gravel and soil. The soil was analyzed (suface and ~6" deep) and we found Co-60, Eu-152 and Mn-54. Surface was 6.5, 5.8 and .08 pCi/g, respectively. Depth sample was 3.5, 3.0 and ND. Gravel was screened out of the sample, and not analyzed. RADSAFE consensus was that activity would be very low or ND in the gravel. |