Abstract The broad beam attenuation of 14 MeV neutrons in a concrete made from limestone aggregate, llimestone dust, and cement has been measured, and shown to be exponential with a tenthe value thickness of 46 cm. The γ-ray dose-rate from activation of this concrete has been compared with that from ordinary concrete, made from graval aggregate, sand and cement. The data for these measurements have been used to estimate the γ-ray exposure rates, in the periods when the neutron generator is switched off, in irradiation rooms constructed from each of these two concretes, and it is shown that the use of the limestone concrete will reduce this radiation hazard by a factor of 5.