Jun
6
Misconceptions About Electromagnetic Pulses
Have you ever gotten into a conversation about doomsday scenarios and someone (maybe you) brings up the dangers of electromagnetic pulses (EMPs)? Maybe it came up during discussions of the recent Infrastructure bill? Did you wonder how much of what was claimed about EMPs was accurate versus based on hearsay or movie lore?
For example, not all EMPs are created equal. There are two types that are cause for worry, both resulting from a nuclear burst at altitudes above 40 km (i.e., 25 miles):
1) E1 (aka “fast pulse”) field: This is created by gamma ray interaction with stratospheric air molecules. Exposed electrical and electronics systems may be upset or permanently damaged.
2) E3 (aka “slow-pulse”) field: Also called a magnetohydrodynamic (MHD) EMP, this is “caused by the distortion of Earth’s magnetic field lines due to the expanding nuclear fireball and the rising of heated, ionized layers of the ionosphere.” It will damage components of long-line systems (i.e., a few kilometers or longer), including the electric power grid and long-haul communication and data networks.
With that as background info, here are six misconceptions about EMPs that can cause the most harm:
Misconception #1) An EMP Will Cause Every Exposed Electronic System to Cease Functioning
“[T]he electric power-grid network and landline communication systems are almost certain to experience component damage when exposed to an EMP with cascading effects to most other (dependent) infrastructure systems.” On the other hand, “small, self-contained systems, such as motor vehicles, hand-held radios, and unconnected portable generators, tend not to be affected;” or, if so, the effect is temporary.
Misconception #2) EMP Effects Will Have Limited, Easily Recoverable, “Nuisance” Effects on Critical Infrastructure Systems
“Although an EMP would not affect every system, widespread failure of a significant fraction of electrical and electronic systems will cause large-scale cascading failures of critical infrastructure networks because [of] interdependencies among affected and unaffected systems.” Examples of unmanned systems most in danger include long-haul communication repeaters, remote pipeline pressure control in supervisory control and data acquisition (SCADA) systems, generator controls in electric power plants, machine process controllers in manufacturing plants.
Misconception #3) Megaton-Yield Nuclear Weapons Are Required to Cause Serious EMP Effects
Regarding an E3, “a 30-KT nuclear weapon above 100 km would cause geomagnetic disturbances as large as solar superstorms, although over smaller regions. It also is worth noting that peak currents on long overhead lines induced by E1 from 10 kiloton-weapons can range in the kiloamperes with voltages reaching into the hundreds of kilovolts.”
Misconception #4) Protecting the Critical National Infrastructure Would Be Cost Prohibitive
“According to Emprimus, a manufacturer of transformer protection devices, the unit cost for high-voltage transformer protection is estimated to be $250,000, with the total number of susceptible large, high-voltage units ranging from 300 to 3,000, according to Oak Ridge National Laboratory. The requirement and cost for generator facility protection are still undetermined but are likely to be similar to transformer protection costs. To protect SCADA systems, replacement parts are readily available and repairs are relatively uncomplicated. Protection costs for heavy-duty grid components are in the $10 billion range [as of 2014], which is a small fraction of the value of losses should they fail. When amortized, protection costs to consumers amount to pennies per month.”
Misconception #5) Only a Late-Time EMP (E3) Will Damage Electric Power-Grid Transformers
“E1 tests of 7.2-KV distribution transformers produced permanent damage to transformer windings in seven of the 20 units tested. The failures were due to transformer winding damage caused by electrical breakdown across internal wire insulation. As an important side note, transformers with direct-mounted lightning surge arrestors were not damaged during the tests.”
Misconception #6) Fiber-Optic Networks Are Not Susceptible to EMP Effects
“In general, fiber-optic networks are less susceptible than metallic line networks; however, fiber-optic multipoint line driver and receiver boxes, which are designed to protect against ground current, may fail in EMP environments. Long-haul telecommunication and regional Internet fiber-optic repeater amplifiers’ power supplies are particularly vulnerable.” Terrestrial fiber-optic cable repeater amplifiers are vulnerable to direct E1 effects, whereas undersea cable repeater amplifiers are vulnerable to E3 effects.
That’s the pared-down version. For more details on all of this, which should interest those of you with interest/knowledge about electricity and electronics, read my source article by George H. Baker, professor emeritus at James Madison University and consultant regarding critical systems in general and EMPs in particular. Baker ends his piece with a bit about standardized solutions.
