Abstract: A process for obtaining useful energy from certain fuel materials, includes the following steps: providing a fuel medium that includes atomic nuclei that have forbidden beta decay transitions; selecting the fuel medium such that cancellation by atomic electrons of an externally applied electromagnetic field at the nucleus is rendered incomplete; applying an electromagnetic field to the fuel medium, the field having an intensity after partial reduction by atomic electrons sufficient to overcome the forbiddenness of beta decay transitions of said nuclei; and recovering useful energy therefrom. In an embodiment, the applied electromagnetic field is operative to provide angular momentum and/or intrinsic parity necessary to overcome forbiddenness. In this embodiment, the atomic nuclei are selected from the group consisting of 90Sr, 137Cs, 87Rb, 48Ca, 40K, 50V, 113Cd, 115In, 96Zr, 85Kr, 99Tc, 135Cs, and 129I.