[en] Electromagnetic interference (EMI) levels were determined experimentally by passive measurement at various locations within two commerical nuclear power plants (NPPs). A description of the measurement locations for each plant and a discussion of how the measurements were made are provided. Photographs of the original time and frequency domain data are provided. The results presented were obtained from one plant while it was operating at high power conditions and from a second plant that was at cold shutdown conditions following a refueling outage. The high frequency currents measured were generally less than 0.5 amperes peak-to-peak, however, currents over 5 amperes were measured. Dominant frequencies tended to be under one megahertz with some as high as 5.2 megahertz. Also presented are levels of voltage pulse peaks occurring on buses which were monitored for several days using power line disturbance monitors