They can penetrate every region of the body. Gamma rays can pass right through a body without ever touching it. Gamma rays that do strike atoms in the body cause ionization of these atoms, which may result in any number of possible chemical reactions that damage the cells of the body. Neutrons, which have the greatest penetrating power of the nuclear radiation hazards, create hazards to personnel when the neutron is captured in atoms of various elements in the body, atmosphere, water or soil. As a result of this neutron capture, the elements become radioactive and release high-energy gamma rays and beta particles.
Initial radiation contains both gamma and neutron radiation.
Residual radiation, our greatest concern, contains both gamma and neutron radiation. The initial nuclear ionizing radiation will ionize the atmosphere around the burst point and produce the EMP, which will contain frequency components in the range from a few to several hundreds of kilocycles per second. The EMP has magnetic and electric field components which exist for only fractions of a second. The magnetic field component is significant inside the radius of the ionized atmosphere and can induce large currents in cables and long-lead wires. These large transient currents may burn out electronic or electrical equipment.