Some Common Misconceptions about Nuclear EMP

Below is an informative paper about EMP. It addresses several common misconceptions. I should also mention that the author, Dr. George Baker, helped me with the research for my thriller Patriarch Run. If you want to learn more about this topic, you can find additional resources in my discussion guide.

2012 Dupont Summit, Carnegie Institute, Washington, D.C. © 2012

© 2012 George H. Baker

 

EMP Knots Untied: Some Common Misconceptions about Nuclear EMP

George H. Baker

George H. Baker Professor Emeritus, James Madison University

Principal Staff, Congressional EMP Commission

Board of Directors, Foundation for Resilient Societies

 

Abstract

There are a number of misconceptions about EMP routinely advanced by both the technical and policy experts, in press reports, on preparedness websites, and even embedded in technical journals. Because many aspects of the EMP generation physics and its effects are obscure and non-intuitive, misconceptions are inevitable.

The wide-area, ubiquitous effects of EMP and the numbers of systems potentially affected make it convenient to adopt misconceptions that avoid the need for action. Denying the seriousness of the effect appears perfectly responsible to many stakeholder groups. On the other extreme, doomsday hyperbole is also present in some camps.

Misconceptions representing over- and under-emphasizing hyperbole have served to deter action in the past. Downplaying the threat places EMP preparedness on the back-burner compared to other effects. Exaggeration of the threat causes policy-makers to dismiss arguments, ascribing them to the “chicken-little” syndrome.

The transcript discusses high priority misconceptions, or “EMP knots:”

1. EMP will burn out every exposed electronic system.

2. EMP effects will be very limited and only result in “nuisance” effects in critical infrastructure systems.

3. Megaton class weapons are needed to cause any serious EMP effects – low yield, “entry-level” weapons do not engender serious EMP effects.

4. To protect our critical national infrastructure would cost a large fraction of the GNP.

5. Only late-time EMP (E3), not E1 will damage electric power grid transformers.

6. Long-haul fiber optic lines are invulnerable to EMP.

7. Ground burst EMP effects are limited to 2-5 km from a nuclear explosion where blast, thermal and radiation effects dominate.

A major impediment to action has been that government and industry are (understandably) swayed by the familiar, the convenient, and the bottom line. Like it or not, familiarity and profitability are the touchstones of acceptability – strategic advantage goes to the acceptable. Thus the tendency exists to downplay the likelihood of an EMP scenario and its associated consequences (Misconception 2). Hopefully, this attempt to redress important and pervasive misconceptions concerning EMP will help to spur action on the challenging effects of EMP and public-private cooperation will begin and prevail in implementing low-risk EMP protection of our most critical infrastructure systems.


There are many misconceptions about EMP that have circulated for many years among both technical and policy experts, in press reports, on preparedness websites, and even embedded in technical journals. This monograph addresses seven of these. Because many aspects of the EMP generation physics and its effects are obscure and non-intuitive, misconceptions are inevitable.

The wide-area, ubiquitous effects of EMP and the numbers of systems potentially affected make it convenient to adopt misconceptions that avoid the need for action. Denying the seriousness of the effect appears perfectly responsible to many stakeholder groups. On the other extreme, doomsday hyperbole is also present in some camps.

Misconceptions representing over- and under-emphasizing hyperbole have served to deter action in the past. Downplaying the threat places EMP preparedness on the back-burner compared to other effects. Exaggeration of the threat causes policy-makers to dismiss arguments, ascribing them to the “chicken-little” syndrome.

The present discussion will be limited to what are perhaps the most harmful misconceptions, or “EMP knots.”

1. EMP will burn out every exposed electronic system.

2. EMP effects will be very limited and only result in “nuisance” effects in critical infrastructure systems.

3. Megaton class weapons are needed to cause any serious EMP effects – low yield, “entry-level” weapons do not engender serious EMP effects.

4. To protect our critical national infrastructure would cost a large fraction of the GNP.

5. Only late-time EMP (E3), not E1 will damage electric power grid transformers.

6. Long-haul fiber optic lines are invulnerable to EMP.

7. Ground burst EMP effects are limited to 2-5 km from a nuclear explosion where blast, thermal and radiation effects dominate.

Misconception 1: EMP will burn out every exposed electronic system.

Based on DoD and Congressional EMP Commission’s EMP test data bases we know that smaller, self-contained systems that are not connected to longlines tend not to be affected by EMP fields. Examples of such systems include vehicles, hand-held radios, and unconnected portable generators. If there is an effect on these systems, it is more often temporary upset rather than component burnout.

On the other hand, threat-level EMP testing also reveals that systems connected to long lines are highly vulnerable to component damage, necessitating repair or replacement. Because the strength of EMP fields is measured in volts per meter, to first order, the longer the line, the more EMP energy will be coupled into the system and the higher the probability of EMP damage. Because of their organic long lines, the electrical power grid network and long-haul landline communication systems are almost certain to experience component damage when exposed to EMP with cascading effects to most other (dependent) infrastructure systems.

Misconception 2: EMP effects will be very limited and cause only easily recoverable “nuisance” type effects in critical infrastructure systems.

Although EMP does not affect every system, widespread failure of limited numbers of systems will cause large-scale cascading failures of critical infrastructure systems and system networks because of the interdependency of the failed subsystems with electronic systems not directly affected by the EMP.

Paul Erdos’ “small world” network theory applies (Duncan Watts, Six Degrees: The Science of the Connected Age, 2004). The graph above illustrates that the average fraction of nodes in any network that are connected to any single network node changes suddenly when the average number of links per node exceeds one. For example, a failed node, where the average links per node is 2, can affect ~ 50% of the remaining network nodes.

Also, for many systems, especially unmanned systems, upset is tantamount to permanent damage – and may cause permanent damage due to control failures. Examples include:

  • Lockup of long-haul communication repeaters
  • Upset of remote pipeline pressure control SCADA systems
  • Upset of generator controls in electric power plants
  • Upset of machine process controllers in manuf. plants

Misconception 3: Megaton-class nuclear weapons are required to cause serious EMP effects. “Entry-level,” kiloton-class weapons won’t produce serious effects.

Due to a limiting atmospheric saturation effect in the EMP generation process, low yield weapons produce peak E1 fields of the same order of magnitude as large yield weapons if they are detonated at altitudes in the 50-80 km range. The advantage of high yield weapons is that their field on the ground is attenuated less significantly at larger heights of burst (that expose larger areas of the Earth’s surface).

The first graph above illustrates that nominal weapons with yields ranging from 3KT – 3MT ( a 3 order of magnitude difference in yield), exhibit a range of peak E1 fields on the ground of only a factor of ~3, viz. 15 -50 KV/meter.

With respect to the late time (E3) EMP field, a 30 KT nuclear weapon above 100 km causes geomagnetic disturbances as large as solar superstorms, but over smaller regions.

The second graph above indicates that megavolt levels and kiloampere-level currents are induced in long overhead lines by E1 from kiloton-class weapons.

Misconception 4: to protect our critical national infrastructure would cost a large fraction of the U.S. Gross National Product.

Of the 14 critical infrastructure sectors, EMP risk is highest for electric power grid and telecommunications grid – attention to these infrastructures alone would bring major benefits to national resiliency. These infrastructures are the most vulnerable due to their organic long lines. And they are also the most critical to the operation and recovery of the other critical infrastructure sectors. It is ironic that our most critical infrastructures are also the most vulnerable to EMP.

If we have to pick one infrastructure to protect, the top choice would be the electric power grid. Grid operational behavior is binary – it fails fast and hard over large regions disabling most other critical infrastructures. The grid is the most essential infrastructure for sustaining population life-support services.

Some major grid components take months to replace – years if large numbers are damaged. The primary example is high voltage transformers (an example unit is pictured in the figure immediately above) which are known to irreparably fail during major solar storms and are thus likely to fail during an EMP event. Protection of these large transformers will buy valuable time in restoring the grid and the life-support services it enables.

The unit cost for HV transformer protection is estimated to be $250,000. The total number of susceptible units range from 300 – 3000 (further assessment is required to establish an exact number.) The requirement and cost for generator facility protection are still undetermined but are likely to be in the same ballpark as transformer protection costs. The need for SCADA system protection is moderated by the ready availability of replacement parts and the relative ease of repair. Doing the math, the protection costs for heavy-duty grid components are in the single digit billions of dollars – a small fraction of the value of losses should they fail. Amortized over twenty years, the protection costs amount to pennies per month for electricity consumers. 

Misconception 5: Only late-time EMP (E3), not E1, will damage electric power grid transformers.

Oak Ridge National Laboratories (ORNL) E1 tests of 7.2 KV distribution transformers produced permanent damage to transformer windings in seven of the twenty units tested. The failures were due to winding damage including turn-to-turn flashover and primary-tosecondary flashover. The results are summarized in the table above (W. Radasky et al, The Early-Time (E1) High-Altitude Electromagnetic Pulse (HEMP) and Its Impact on the U.S. Power Grid, Meta-R-320, Oak Ridge National Laboratories).

As an important side-note, transformers with directmounted lightning surge arrestors were not damaged during the tests. Similar tests of HV transformers are needed. 2 W. Radasky et al, The Early-Time (E1) High-Altitude Electromagnetic Pulse (HEMP) and Its Impact on the U.S. Power Grid, Meta-R-320, Oak Ridge National Laboratories.

Misconception 6: Optical fiber networks are not susceptible to EMP effects.

In general optical fiber networks are less susceptible than metallic line networks; however fiber optic line driver and receiver boxes (top figure) may fail in EMP environments. Long-haul telecom and internet optical fiber repeater amplifiers’ power supplies are particularly vulnerable to EMP environments (bottom figure). Terrestrial fiber-optic cable repeater amplifier power is provided by the electric power grid and thus vulnerable to grid failure as well as direct EMP/E1 effects. Undersea cable repeater amplifiers are also vulnerable to EMP/E3 effects since they are connected to a coaxial metallic power conductor that runs the length of the line. Because of its low frequency content, E3 penetrates to large ocean depths subjecting undersea power amplifiers to high risk of burnout.

On the plus side, line drivers/receivers and repeater amplifiers are relatively easy to protect using shielding, aperture treatment, and power line filters and/or breakers.

Misconception 7: Ground burst EMP effects are limited to 2-5 kilometers from a nuclear explosion in the region where blast, thermal and radiation effects dominate. Thus, ground burst EMP is not a major threat.

Ground bursts couple large currents to long lines running through the nuclear source region. These currents propagate to distances of tens of kilometers from the burst location. Destructive source region EMP (SREMP) effects on power and communications infrastructure extend significantly beyond the blast, thermal and radiation effects ranges. As shown in the figure, a nominal 10KT yield ground burst delivers a 2,000 amp pulse lasting for several milliseconds on overhead power line at 20km. A 1 MT ground burst would deliver 150,000 amps at the same distance down the line. Long-line currents induced by a single burst can debilitate long-line communication and electric power networks over the area of a large city.

Conclusion.

The seven EMP “knots” addressed here are common misconceptions and arguably the most important to “untie.” There are others that should be addressed, but the present list, especially the first four, must absolutely be dispelled because they continue to deter efforts to achieve national preparedness.

From a risk-based priority standpoint, the electric power grid is at the top of the list for EMP protection (G. H. Baker, . "Risk-Based Critical Infrastructure Priorities for EMP and Solar Storms" Security Analysis and Risk Management Association Newsletter.October 2011). Hardening this infrastructure alone would have major benefits for national resiliency, i.e. the ability to sustain, reconstitute and restart critical services. It is not just the survivability of our electric power infrastructure that is at stake; almost all of our critical infrastructure services will cease should the power grid fail.

A major impediment to action has been that government and industry are (understandably) swayed by the familiar, the convenient, and the bottom line. Like it or not, familiarity and profitability are the touchstones of acceptability – strategic advantage goes to the acceptable. Thus the tendency exists to downplay the likelihood of an EMP scenario and its associated consequences (Misconception 2).

By way of encouragement, we know how to protect systems against EMP. EMP engineering solutions have been implemented and standardized by DoD on a host of systems. In the case of the national power grid, the installation of blocking devices in the neutral-to-ground conductors of large electrical distribution transformers will significantly reduce the probability of damage from slow E3 component of EMP and geomagnetic disturbances (GMDs) caused by solar storms. Transformer protection against E1 overvoltages is achievable by installing common metal-oxide varistors (MOVs) on transformers from each phase to ground. Costs for protecting the power grid are a micro-fraction of the value of the systems and services and risk.

EMP protection methods for communication and control facilities have been developed and implemented by DoD since the 1960s and are well documented (ref. MIL-STD-188-125-1, MILSTD-188-125-2, MIL-HDBK-423). Engineering approaches include use of shielded enclosures, provision of backup power, standard grounding techniques, installation of overvoltage protection devices and filters on penetrating conductors, and good cable management procedures.

Hopefully, this attempt to redress important and pervasive misconceptions concerning EMP will help to spur action on the challenging effects of EMP and public-private cooperation will begin and prevail in implementing low-risk EMP protection of our most critical infrastructure systems.

Benjamin Dancer

Benjamin is the author of the literary thriller Patriarch Run, the first book in a series that will include Fidelityand The Story of the Boy. He also writes about parenting, education, sustainability and national security.

Benjamin works as an Advisor at a Colorado high school where he has made a career out of mentoring young people as they come of age. His work with adolescents has informed his stories, which are typically themed around fatherhood and coming-of-age.

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