This is a follow up to a previous post on Nuclear Uncertainty.


Let’s talk about a potential use of nuclear weapons that isn’t about nuclear winter, but could still have devastating consequences. Nuclear explosions produce EMPs (Electromagnetic Pulses). There are other things that can do this (lightning, coronal mass ejections from the sun), but today we’re going to talk about NEMPs (Nuclear Electromagnetic Pulses). A NEMP is a burst of electromagnetic radiation that produces rapid changes in electric and magnetic fields. The resulting spikes in electricity can do a lot of damage to electrical infrastructure.

The information we have about NEMPs comes from tests that were conducted by the US and Russia before the Nuclear Test Ban Treaty. This means data is limited, but there’s still a lot that can be inferred from the information we do have.


Background Info:

There are 3 types of EMP produced by nuclear weapons. A nuke detonated above 100 km produces all 3 (Greetsai, et al 1998).

  • Early-time EMP (E1)
    • Very fast, but short electromagnetic field. High voltages produced cause damage to Ordinary surge protectors don’t protect against it because it is changing on the scale of nanoseconds.
  • Intermediate-time EMP (E2)
    • Lasts less than a second. Similar to the effects of lightning so it is easier to protect against, but can cause damage to circuits already damaged by E1.
  • Late-time EMP (E3)
    • Lasts tens to hundreds of seconds. Is similar to geomagnetic activity caused by a solar storm. Can travel along electrical lines and do damage to transformers (the power line kind not the giant mech robot kind).


The Tests:

The US and Russia both conducted high altitude detonations to test the properties of NEMP.

Operation Fishbowl:

The US tested a 1.4 Megaton bomb 400 km above the Pacific. There were two surprises. Some street lights in Honolulu went out 400 nautical miles away. AND! It caused a buildup of radiation in the Van Allen belts (charged particles around earth captured by earth’s magnetic field). This disabled all publicly acknowledged space assets at the time (Frankel et al 2015).

Project K:

Russia did a series of tests over Kazakhstan. In one of these tests a 500 km long communication line was damaged. At all of the safety points surge arrestors were fired and fuses were blown. The closest end of the power line was 180 km from  the point of land directly below the burst (Greetsai, et al 1998).

The risk to long electrical and communication lines is real, but infrastructure could be hardened against damage. The late time EMP in the Kazakhstan test caused a current of about 4 amps. The fuses failed at about 1 amp(Greetsai, et al 1998).


Level of Preparation:

Even though the data from tests is limited, they provided valuable information on how much power nuclear EMP creates. Since the amount of damage done by EMP is relatively predictable, the technical aspects seem surmountable.

Selection_060E3 effects are dependent on the energy of the weapon detonated, but E1 effects are “saturation-limited”, meaning it’s mostly uniform over a large area regardless of size (Wilson, 2008).

Although the DoD has engaged in hardening some systems, experts on the EMP commision do not think the private sector or state governments are adequately prepared for EMP. One problem is that standard surge arrestors used to protect against lightning, do not close fast enough to protect against EMP (Wilson, 2008). Making safety measures that are able to react to the speed of E1 waves would be an important feature of adequate preparation. Many consumer electronics and commercial systems could be damaged by NEMP. With a lot of infrastructural damage, recovery times could be pretty drastically increased. This would clearly depend on the scope of the damage, but large scope EMP damage can be achieved through use of a relatively small number of nuclear weapons. Really just one as illustrated above.


Coordination/Political Problems:

NEMP has been studied by many agencies, but the application of safety measures has been spotty even in military equipment. The EMP Commission was unable to convince the Department of Homeland Security to add EMP to National Planning Scenarios. This may be due to conflicting research about the effects of EMP on commercial electronics (Wilson, 2008). Regardless, coordination between industry and government would likely be required to protect infrastructure against EMP. I suspect that even protection of a small portion of infrastructure could drastically reduce recovery times, saving lives and money.


Large Power Transformers:

One reason to be concerned is the electrical infrastructures dependence on Large Power Transformers (LPTs). LPTs are huge and expensive. They use a lot of expensive materials like electrical steel and copper. Each LPT costs millions of dollars.


(Hoffman & Bryan 2012)


The big problem comes in with getting infrastructure back up and running after EMP (nuclear or otherwise) takes out many LPTs at once. The time it takes to replace an LPT is currently 5-16 months. This depends on a lot of things like where it’s manufactured and how quickly materials can be acquired. This month’s long production period is with infrastructure functioning. Presumably it would be longer with electrical infrastructure disabled.


(Hoffman & Bryan 2012)


Hardening the US Grid:

In his testimony to the congressional EMP committee in 2017, Dr. George Baker (who managed the development of military standards to protect DoD systems against EMP) warned that risks to the electrical grid could cause millions of casualties and do trillions of dollars of damage. He also pointed out that solutions to protect electrical systems are well known and technically feasible. He emphasized the importance of government and industry working together to make the Us electrical grid resilient or able to quickly recover from EMP or other risks.


DARPA is working on hardening the US electrical grid against cyber attack and ensuring quick recovery were a cyber attack to occur. Some portion of this work would probably overlap with safeguards for EMP, but it wasn’t clear from what I’ve read that this would include being able to quickly replace civilian communication networks or replace Large Power Transformers.



The uniformity of E1 waves and the travelling of E3 waves along electrical lines means large portions of electrical infrastructure could be damaged by a relatively (compared to nuclear winter scenarios) small number of nukes. NEMP is better understood than nuclear winter, in terms of risk mitigation, that’s good. We can prepare by hardening infrastructures, making response plans that include replacing electrical infrastructure, and prepare in other ways (like growing food without electricity) for grid failure. Preparing for large scale disaster requires coordination on a scale that only seems achievable through governments or other large organization, so the most useful preventive actions are probably in the area of convincing governments and organizations to make sensible preparations and response plans.



Baker III, G. H. (2017). Testimony of Dr. George H. Baker, Senior Advisor to the Congressional EMP Commission.

Frankel, M., Scouras, J., & Ullrich, G. (2015). The Uncertain Consequences of Nuclear Weapons Use. JOHNS HOPKINS UNIV LAUREL MD APPLIED PHYSICS LAB

Greetsai, V. N., Kozlovsky, A. H., Kuvshinnikov, V. M., Loborev, V. M., Parfenov, Y. V., Tarasov, O. A., & Zdoukhov, L. N. (1998). Response of long lines to nuclear high-altitude electromagnetic pulse (HEMP). IEEE transactions on electromagnetic compatibility

Hoffman, P., & Bryan, W. (2012). Large power transformers and the US electric grid. Report of US Department of Energy.

Rivera, M. K., Backhaus, S. N., Woodroffe, J. R., Henderson, M. G., Bos, R. J., Nelson, E. M., & Kelic, A. (2016). EMP/GMD Phase 0 Report, A Review of EMP Hazard Environments and Impacts (No. LA-UR-16-28380). Los Alamos National Laboratory (LANL)

Wilson, C. (2008, July). High altitude electromagnetic pulse (HEMP) and high power microwave (HPM) devices: Threat assessments