Under certain conditions, the induced current can exceed the limits specified in Table of Annex A, even though the electric field strengths are below the limits specified in tables and of Annex A. These conditions may occur even when the electric field strength is as low as 25% of the exposure limit. Therefore, induced current through a single foot should be measured by using a clamp-on current probe or a low-profile platform consisting of two parallel conductive plates isolated from each other with one located above the other when the electric field is 25% of the uncontrolled environment limit or higher. The initial induced current measurements should be taken at the locations with the highest field strength.
All chemical elements may be rendered radioactive by adding or by subtracting (except for hydrogen and helium) neutrons from the nucleus of the stable ones. Studies of the radioactive decays of new isotopes far from the stable ones in nature continue as a major frontier in nuclear research. The availability of this wide variety of radioactive isotopes has stimulated their use in a wide variety of fields, including chemistry, biology, medicine, industry, artifact dating, agriculture, and space exploration. See Alpha particles , Beta particles , Gamma rays , Isotope