γ-ray emitters in concrete

Difficulties experienced in planning the construction of a low-background counting facility are discussed. Provision should be made for both the radioactive assay of all materials which will become part of the structure and the opportunity to reject those which contain enough activity to affect the level of background radiation significantly. Results of such an assay of concrete constituents (mix, sand, cement and gravel) from a number of suppliers are shown. γ-ray emitters which were identified in each of the samples were 226Ra, 228Ra, 228Th and 40K. (U.K.)