Resolution of Generic Safety Issues: Issue 20: Effects of Electromagnetic Pulse on Nuclear Power Plants (Rev. 1) ( NUREG-0933, Main Report with Supplements 1–34 )
This concern was raised183 because of the potential for a high-altitude nuclear weapon detonation causing a large electromagnetic pulse (EMP) which subsequently could induce large currents and voltages in electrical systems. The concern was that sensitive electronics at nuclear power plants could be irreparably damaged. In addition, Petitions for Rulemaking on EMP (PRM-50-32, 32A, and 32B) have been filed.
This issue is unique because of its ability to affect more than one plant at the same time. Portions of a nuclear power plant's electrical, instrumentation and control systems may be disabled due to the large currents and voltages which could be induced. Loss of critical systems such as offsite power, emergency onsite power, etc., could lead to loss of core cooling with subsequent core melt.
The original concern was that sensitive electronics would be irreparably damaged, but it now appears that, if failure occurred, it would likely be only momentary (i.e., trip breakers, etc.) and the failed equipment could be restored to service to continue core heat removal.115
If the electrical equipment necessary for safe shutdown displayed sensitivity to EMP, then a minimum safety margin for the ratio of the peak EMP voltage to its damage threshold voltage could be chosen and the equipment would then be required to meet this criterion. This could then provide assurance that the equipment would not be damaged.
Detailed programmatic information on this issue was presented in SECY-81-641604 and subsequent program status reports were provided in SECY-82-157605 and SECY-82-157A.203 A study on the effects of EMP on nuclear power plants was documented in NUREG/CR-3069115 and forwarded to the Commission in SECY-83-367.606 This issue was RESOLVED with the Commission approval607 of the staff's report and no new requirements were established. Continuing staff work in response to the PRMs is a separate entity and does not affect this conclusion.