Ensuring Electricity Infrastructure Resilience Against Deliberate Electromagnetic Threats

December 14, 2022 R47339

Ensuring Electricity Infrastructure Resilience
December 14, 2022
Against Deliberate Electromagnetic Threats
Brian E. Humphreys
Detonation of a nuclear weapon in the Earth’s upper atmosphere or near-Earth space may
Analyst in Science and
generate a series of electromagnetic pulses—known as high-altitude electromagnetic pulse
Technology Policy
(HEMP)—that damage critical infrastructure on the Earth’s surface. Observers are most

concerned about potential HEMP effects on the electricity sector, given its specific vulnerabilities
to electromagnetic threats and its role in maintaining the full range of essential infrastructure

functions nationwide.
Scientists believe HEMP is generated by the interaction of the radiation and blast effects of an exploding nuclear device with
the earth’s upper atmosphere, magnetic field, and conductive geologic formations. HEMP has three main time components,
usually labeled E1, E2, and E3, which occur in rapid sequence and create distinct and potentially hazardous effects over a
broad geographic area. The E1 pulse may directly radiate sensitive electronics or couple with electrical equipment via control
cables or other conductors. The E2 pulse has effects similar to lightning. The E3 pulse may induce currents in long-distance
transmission lines that damage or disrupt large power transformers (LPTs) and other essential equipment.
While there is broad consensus in the electricity industry, the research community, and among policymakers that HEMP
attacks may pose risk to electricity infrastructure, there is disagreement regarding specific HEMP hazard characteristics, the
level of risk, and the need for—or feasibility of—expansive hardening initiatives. Although the basic theories underlying
HEMP research are well-established, HEMP involves a range of complex physical phenomena—from sub-atomic processes
to complex interactions of networked infrastructure systems under stress—which are not fully understood. The degree (and
policy relevance) of scientific uncertainty is itself a significant source of disagreement among stakeholders.
In recent decades, Congress has pressed the research community and relevant federal agencies to advance scientific
understanding of HEMP-related hazards to infrastructure, and to produce more authoritative risk assessments to inform both
policy development and industry action. Congress has enacted a variety of mandates—primarily via national defense
authorization acts—to spur basic research, applied research, and technology development, as well as risk management
activities such as risk assessments, adoption of voluntary standards and best practices, and the expansion of public-private
partnerships for coordination and information sharing with industry. A congressionally-chartered expert commission
provided congressional testimony, reports, and recommendations between 2004 and 2017.
The 117th Congress has appropriated funds for new infrastructure investments through the Infrastructure Investment and Jobs
Act (IIJA; P.L. 117-58) and the Inflation Reduction Act (IRA; P.L. 117-169), even as implementation of previous mandates
continued. Rapid introduction of solar and wind generation of electricity, microgrids, and utility-scale energy storage may
offer potential resilience benefits, but could also introduce new vulnerabilities. Likewise, new operational control
technologies to support integration of distributed energy resources with existing distribution networks may offer additional
flexibility and resilience to the grid—assuming potentially sensitive electronic components are not damaged by HEMP.
Research into the resilience of these technologies against HEMP is in its early stages. Research gaps complicate guidance to
policymakers or industry stakeholders on near-term prioritization of critical systems and assets for hardening or other
countermeasures. As a remedy, some IIJA provisions include HEMP research as an authorized activity. Other provisions may
support HEMP research, but do not specifically authorize it. Actual support for HEMP resilience will largely depend upon
how funds are apportioned to specific programs by implementing agencies.
Several other issues for Congress may also warrant attention. Gaps in data used to model HEMP hazards and their effects on
infrastructure have long been identified as an obstacle to providing more authoritative risk assessments to key stakeholders.
Improved coordination and information sharing between defense and civilian researchers may address some gaps.
Additionally, resilience of new technologies to HEMP is an emerging concern. Congress may support additional research and
development of resilience standards through its oversight and legislative authorities, while considering potential future
technological advancements as appropriate. Emerging solid state technologies may enable introduction of standardized
systems to replace older technologies, such as LPTs that require long lead times for manufacture, customization, and
transport. Given the long service life of most electricity infrastructure assets, it may be appropriate to encourage investment
in next-generation technologies, where possible, to avoid inefficient use of limited resources to harden obsolescent
technologies against HEMP.
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Appendixes
Appendix A. Selected Studies by Year .......................................................................................... 25

Contacts
Author Information ........................................................................................................................ 27

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Ensuring Electricity Infrastructure Resilience Against Electromagnetic Pulse Threats

Introduction
Detonation of a nuclear weapon in the upper atmosphere or in near-Earth space may generate a
series of electromagnetic pulses—known collectively as high-altitude electromagnetic pulse
(HEMP)—that damage the electric grid and other critical infrastructure on the earth’s surface.1
HEMP may directly radiate and damage sensitive electronics used to operate the grid, or couple
with transmission lines and other conductors attached to essential equipment. This report focuses
on HEMP-related risk to the electric grid, given its centrality to the operation of many other
critical networked systems, such as water, transport, and communications. Other deliberate
electromagnetic threats, such as battlefield electromagnetic pulse (EMP) weapons or improvised
devices powered by conventional explosives, are outside the scope of this report. Likewise, this
report does not provide an assessment of intent or capabilities of potential adversaries, or the
likelihood of a HEMP attack.2
While there is broad consensus in the electricity industry, the research community, and among
policymakers that high-altitude electromagnetic pulse attacks may pose risk to electricity
infrastructure, there is disagreement regarding specific HEMP hazard characteristics, the level of
risk, and the need for—or feasibility of—expansive HEMP-hardening initiatives.3
Congress has enacted a variety of mandates—primarily via national defense authorization acts—
to spur basic research, applied research, and technology development, as well as risk management
activities, risk assessments, adoption of voluntary standards and best practices, and the expansion
of public-private partnerships for coordination and information sharing with industry. A
congressionally chartered expert commission provided congressional testimony, reports, and
recommendations between 2004 and 2017.
Most federal legislation has focused on the electricity sector, reflecting the broad consensus and
priorities of government, industry, and the research community. Implementation of previous
congressional mandates is ongoing, even as the 117th Congress has appropriated funds for new
infrastructure investments through the Infrastructure Investment and Jobs Act (IIJA; P.L. 117-58),
the Inflation Reduction Act (IRA; P.L. 117-169), and other legislation. Prospective upgrades and
buildout of electricity infrastructure may affect the sector’s overall resilience to HEMP hazards,

1 The Cybersecurity and Infrastructure Security Agency (CISA), a Department of Homeland Security agency,
designates electricity as a subsector of the Energy critical infrastructure sector, which includes generation,
transmission, and distribution except for hydroelectric and commercial nuclear power facilities. See Department of
Homeland Security and Department of Energy, Energy Sector Specific Plan, Washington, DC, 2015, p. 3,
https://www.cisa.gov/sites/default/files/publications/nipp-ssp-energy-2015-508.pdf. As used in this report, “electricity
sector” encompasses the entirety of the national generation, long distance transmission, and local distribution
infrastructure.
2 The congressionally-chartered Commission to Assess the Threat to the United States from Electromagnetic Pulse
Attack (the EMP Commission) released several papers assessing foreign adversaries’ intent and capabilities prior to its
dissolution. See Peter Vincent Pry, Foreign Views of Electromagnetic Pulse Attack, the EMP Commission,
Washington, DC, July 2017; ibid., Political Military Motives for Electromagnetic Pulse Attack, the EMP Commission,
Washington, DC, July 2017; and ibid., Nuclear EMP Attack Scenarios and Combined-Arms Cyber Warfare,
Washington, DC, July 2017. Available online at http://www.firstempcommission.org/.
3 Some experts believe that certain of these hardening measures to protect essential grid equipment or maintain
stockpiles of spare equipment may make the grid more resilient against more-frequently occurring electromagnetic
threats from space weather, cyber, or physical attacks, providing additional potential benefits. See The Commission to
Assess the Threat to the United States from Electromagnetic Pulse (EMP) Attack, Report of the Commission to Assess
the Threat to the United States from Electromagnetic Pulse (EMP) Attack, Critical National Infrastructures (the EMP
Commission critical infrastructure report),Washington, DC, April 2008, p. 53, http://www.firstempcommission.org/
uploads/1/1/9/5/119571849/emp_comm._rpt._crit._nat._infrastructures.pdf.
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either by design or by chance. Congress may exercise oversight of related programs and activities
to ensure that HEMP resilience is incorporated into electricity infrastructure at desired levels.
This report provides information on (1) the basic physics of HEMP; (2) existing risk management
approaches and related legislation, policies, and directives; (3) the current state of scientific
knowledge and related research programs; and (4) emerging science and technology policy
issues. A concluding section summarizes potential issues for Congress.
High-Altitude Electromagnetic Pulse (HEMP) and
Hazards to Electricity Infrastructure
U.S. and Soviet high-altitude weapons tests in the upper atmosphere in the late 1950s and early
1960s suggested that the electromagnetic effects of nuclear bombs detonated at high altitude
(above 30 km) were potentially damaging to electrical grids, communications infrastructure, and
other vital electronics-based systems many hundreds of miles away from the blast epicenter.
Therefore, HEMP became a phenomenon of concern to military and civil defense planners.
The Partial Test Ban Treaty of 1963, signed by the United States, the United Kingdom, and the
Soviet Union, precluded further scientific observations of HEMP effects on infrastructure in situ.4
However, military and civilian scientists have continued theoretical work and laboratory testing
on grid components and other electronics. In addition, naturally occurring space weather produces
geomagnetic disturbances (GMD)—comparable in some aspects to the late-time (E3)
magnetohydrodynamic pulse produced during HEMP events—that inform empirical research on
large-scale electromagnetic hazards to infrastructure in natural settings.5
The HEMP Waveform
In general, scientists believe HEMP is generated by the interaction of the radiation and blast
effects of an exploding nuclear device with the earth’s upper atmosphere, magnetic field, and
conductive geologic formations. HEMP has three main time components, usually labeled E1, E2,
and E3, which occur in rapid sequence and create distinct and potentially hazardous effects over a
broad geographic area.

4 See the National Archives, “Test Ban Treaty (1963),” https://www.archives.gov/milestone-documents/test-ban-treaty.
5 Space weather refers to the dynamic conditions in Earth’s outer space environment. This includes conditions on the
Sun, in the solar wind, and in Earth’s upper atmosphere. Both space weather-related geomagnetic disturbances and the
late-time high-altitude magnetohydrodynamic pulse cause disturbances in the Earth’s ambient magnetic field that may
cause geologically induced currents, although there are significant differences in rise time, duration, geographic
distribution, and amplitude. See Ross Guttromson, Craig Lawton, and Matthew Halligan, et al., Electromagnetic
Pulse—Resilient Electric Grid for National Security: Research Program Executive Summary, Sandia National
Laboratories, SAND2020-11227, Albuquerque, NM, October 2020, p. 15; and Maj. David Stuckenberg,
“Electromagnetic Pulse Threats to America’s Electric Grid: Counterpoints to Electric Power Research Institute
Positions,” Over the Horizon: Multi-Domain Operations and Strategy, pp. 17-18, August 27, 2019. For more
information on space weather threats to infrastructure and federal risk management programs and activities, see CRS
Report R46049, Space Weather: An Overview of Policy and Select U.S. Government Roles and Responsibilities, by Eva
Lipiec and Brian E. Humphreys.
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Figure 1. Representation of HEMP Electric Field

Source: Edward Savage, James Gilbert, and Wil iam Radasky, The Early-Time (E1) High-Altitude Electromagnetic
Pulse (HEMP) and Its Impact on the U.S. Power Grid, Metatech, Meta-R-320, Goleta, CA, January 2010, p. 2-2.
Notes: E(t) (V/m) = electric field in Volts per meter. s = seconds. E1 is seen in the upper left quadrant of the
graph as a rapid rise in electromagnetic energy. E2 is seen in a less pronounced peak in the middle of the graph.
E3 is seen at the far right as two lower amplitude pulses. The graph is il ustrative and provides only a generic
representation of HEMP electric fields and timescales.
E1: Early Time Pulse
The fission component of a modern nuclear weapon (typically used to trigger a more powerful
fusion reaction) releases an intense burst of gamma radiation within the first microsecond of
detonation. When detonations occur at high altitude, the radiation ionizes air molecules in the
gamma absorption layer roughly 30 kilometers (km) above the earth’s surface. Electrons freed by
this process scatter and interact with the earth’s upper atmosphere and magnetic field before
losing their energy and being reabsorbed a short time later. The brief, but high energy, movement
of free electrons along the lines of the earth’s ambient magnetic field generates a secondary
electromagnetic pulse. Dependent on a number of conditions, part of this pulse may radiate
downward towards Earth’s surface as a high-amplitude radio signal.6
Although this E1 pulse may reach continental scale, the maximum strength of the electric field it
generates—measured in kilovolts per meter (kV/m)—is concentrated within a smaller crescent-
shaped area equatorward (i.e., southward in the Northern hemisphere) of the blast epicenter (see
Figure 2) due to the influence of the Earth’s magnetic field. The E1 pulse may damage electrical
systems and electronic devices in two ways: (1) direct radiation of internal components, or (2)
coupling with conductors, such as power transmission lines, power control lines, and certain

6 For detailed description of HEMP physics, see Michael Kelly Rivera, Scott N. Backhaus, and Jesse Richard
Woodroffe, et al., EMP/GMD Phase 0 Report, A Review of EMP Hazard Environments and Impacts (the LANL study),
Los Alamos National Laboratory, LA-UR-16-28380, Los Alamos, NM, November 7, 2016, pp. 13-34,
https://www.osti.gov/biblio/1330652. This section synthesizes descriptions of HEMP physics found in the LANL study
and other studies cited in this report. According to the LANL study, most contemporary HEMP research is based on
theories and insights from a series of research papers published between 1962 and 1986 by W.J. Karzas and Richard
Latter, and Conrad Longmire et al. The authors provide the following disclaimer about their description of E1 physics:
“To aid in the understanding of the phenomena, a number of [technically inaccurate] simplifications have been made. ...
Although we have presented the above as if it was ‘settled’ science, by no means is this the case. Models of the E1
pulse incorporating more physical effects and more detail on the effects we described above are still being developed to
this day” (p. 27).
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communications lines, which act as antennae and may conduct damaging voltage surges into
connected devices.
Figure 2. Potential HEMP E1 Effects of 1,000 Kiloton Weapon at 200 km Altitude
over Central United States

Source: Los Alamos National Laboratory, in Electric Power Research Institute (EPRI), High-Altitude
Electromagnetic Pulse and the Bulk Power System: Potential Impacts and Mitigation Strategies (the EPRI study), Palo
Alto, CA, April 2019, p. 2-3, https://www.roxtec.com/globalassets/03.-files/campaign-pages/emc/2019-epri-
report.pdf.
The strength of the E1 pulse is only weakly correlated with increased weapon yield, because the
same process that generates the radio signal described above also creates a powerful return
current that builds throughout the E1 phase of the HEMP event. The return current partially
attenuates the primary signal.7 Height of burst also affects the strength of HEMP E1 hazard fields
measured on the earth’s surface. E1 effects are limited to line of sight from the epicenter to the
earth’s surface, so that detonations at higher altitudes affect a wider geographic area. As with any
source of radiation, the intensity of illumination decreases with distance from the source. Any
given weapon yield has an “optimal” height of burst wherein the strength of the hazard field
created by the E1 pulse is maximized as shown in Table 1.
Table 1. HEMP E1 Maximum Waveforms as a Function of Weapon Yield and Altitude
Yield (kilotons)
Altitude (km)
Epeak (kV/m)
10
50
18
30
58
26
100
67
36
300
77
46
1,000
88
57
Source: Defense Threat Reduction Agency (DTRA), Department of Defense (DOD).
Notes: Adapted by CRS. For comparison, yield of the bombs used to destroy Hiroshima and Nagasaki were
estimated by LANL in 1985 to be 15 kilotons and 21 kilotons respectively. Yield of modern Russian strategic
weapons deployed on intercontinental ballistic missiles range between 100 and 800 kilotons, according to a 2022
Bul etin of the Atomic Scientists report.

7 LANL study, pp. 26-27.
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The geographic area of maximum E1 electric field strength does not necessarily overlap with the
geographic areas where infrastructure assets are most vulnerable to E1 hazards, according to a
2019 study by the Electric Power Research Institute (EPRI), an industry group. The report states
that “maximum coupling generally occurs in areas to the east and west of ground zero and not
south of ground zero where the area of maximum electric field amplitude is located.”8
Peak field strength is therefore only one of several factors affecting overall risk to exposed
electricity infrastructure. Other factors listed in the EPRI study include polarization of the E1
field, incidence angle between burst location and location of the asset on the ground, and
azimuthal angle—the angle between the wave of electromagnetic energy and a wire or other
conductor on or near the Earth’s surface.9
E2: Intermediate Time Pulse
The E2 pulse (between 1 microsecond and 1 tenth of a second after detonation) is also generated
by the fission component of a nuclear weapon.10 The E2 pulse creates an electric discharge
similar to lightning in its basic physics, but occurring over a much wider geographic area. Many
scientists believe protective equipment that is already installed to prevent damage to the electric
grid from lighting strikes is sufficient to mitigate E2 effects. However, some have cautioned that
the earlier E1 pulse may damage this protective equipment, leaving grid infrastructure exposed to
hazardous effects of the E2 pulse.11 Despite this uncertainty, most EMP research focuses on the
E1 and E3 pulses and their effects.
E3: Late Time Pulse
E3 is generated by the fusion component of a nuclear device. The physics and time scale of the
E3 pulse differ from those of E1 and E2, because E3 is produced by the explosive effects of the
device, not the initial release of gamma radiation from the fission reaction described above (see
the “E1: Early Time Pulse” section). According to the LANL study, “The primary physical effect
at work in the E3 phase involves the motion of plasma, ionized weapon debris, and ionized
atmosphere within the Earth’s magnetic field.”12 In general, E1 and E3 effects cannot be
maximized simultaneously with a single weapon, because parameters such as optimal weapon
yield and optimal detonation altitude are different for E1 and E3. Even so, significant E1 and E3
effects on the earth’s surface may overlap in some cases.13

8 Electric Power Research Institute (EPRI), High-Altitude Electromagnetic Pulse and the Bulk Power System: Potential
Impacts and Mitigation Strategies (the EPRI study), Palo Alto, CA, April 2019, p. 2-9, https://www.roxtec.com/
globalassets/03.-files/campaign-pages/emc/2019-epri-report.pdf.
9 The EPRI study, pp. 2-7–2-8.
10 The LANL study, p. 18.
11 A.G. Tarditi, J.S. Besnoff, and R.C. Duckworth, et al., High-Voltage Modeling and Testing of Transformer, Line
Interface Devices, and Bulk System Components Under Electromagnetic Pulse, Geomagnetic Disturbance, and Other
Abnormal Transients, Oak Ridge National Laboratory (ORNL), ORNL/TM-2019/1143, Oak Ridge, TN, March 18,
2019, p. 4 and 8; and the EMP Commission critical infrastructure report, p. 33, http://www.firstempcommission.org/
uploads/1/1/9/5/119571849/emp_comm._rpt._crit._nat._infrastructures.pdf.
12 The LANL study, p. 27.
13 Brian Pierre, Daniel Krofcheck, and Matthew Hoffman, et al., EMP-Resilient Grid Grand Challenge: Task 3.1 Final
Report, Modeling Framework for Bulk Electric Grid Impacts from HEMP E1 and E3 Effects, SAND2021-0865,
Albuquerque, NM, January 2021, p. 20, https://www.osti.gov/biblio/1764794.
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The two primary components of the E3 pulse are the “blast” component (E3A) and the “heave”
component (E3B). The E3A component is caused by the expansion of a large superheated
conductive plasma ball produced by the detonation. The plasma ball pushes the earth’s ambient
geomagnetic field lines outwards as it expands and rises through the upper atmosphere. Much of
the E3A component is attenuated by the effects of atmospheric absorption of the weapon’s x-ray
emissions below the blast epicenter, and so presents a lesser risk to infrastructure.
The E3B pulse is produced later as the plasma ball and associated effects dissipate, and the
“ionized remnants of bomb debris and shock-heated atmospheric ions” settle in the upper
atmosphere below the blast epicenter. This creates a conductive “hot ion patch,” which heats and
expands. This heated conductive patch becomes buoyant and rises through the upper atmosphere,
producing an artificial geomagnetic disturbance as it pulls the geomagnetic field lines inwards.14
According to a LANL model of an E3B environment, location of peak voltages changes over the
course of the event.15 Figure 3 depicts the geoelectric hazard field 40 seconds after the blast.
Figure 3. Notional Geoelectric Field of “Heave” E3B Pulse at 40 Seconds
10,000 Kiloton Yield at 200 km (Magnitude in V/km)

Source: LANL diagram in EPRI Study.
Notes: The graphic does not depict predicted effects of a specific weapon.
As with E1, weapon yield and height of burst affect the strength of the resulting E3B hazard field.
However, the magnitude of the E3B pulse does not increase much after weapon yield exceeds 10
kilotons—a yield typical of a small tactical warhead. However, the surface area of the hot ion
patch increases with weapon yield and may disrupt Earth’s magnetic field over a larger area.16 A
larger patch presents greater risk to electricity infrastructure, because the resulting E3B pulse
causes geomagnetic induced currents (GIC) that build cumulatively as they flow through long
conductors, such as long-distance transmission lines.17

14 See the LANL study, p. 35.
15 See the EPRI study, p. 2-11.
16 See the LANL study, pp. 38-39; and James Gilbert, John Kappenman, and William Radasky, et al., The Late Time
(E3) High-Altitude Electromagnetic Pulse (HEMP) and Its Impact on the U.S. Power Grid, Metatech, Meta-R-321,
Goleta, CA, January 2010, p. 2-15, http://www.futurescience.com/emp/ferc_Meta-R-321.pdf.
17 For detailed description of E3 physics, see Jeffrey J. Love, Greg M. Lucas, and Benjamin S. Murphy, et al., “Down
to Earth with Nuclear Electromagnetic Pulse: Realistic Surface Impedance Affects Mapping of the E3 Geoelectric
Hazard,” Earth and Space Science, vol. 8 (2021).
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GIC may saturate the magnetic cores of large power transformers (LPTs) that enable transmission
and local distribution of alternating current at useable voltages. According to a Department of
Energy (DOE) study on naturally-occurring geomagnetic disturbances, saturation of the magnetic
cores of LPTs by GIC can cause several damaging effects:18
 harmonic currents that can cause relays to trip equipment;
 fringing magnetic fields (i.e., flux outside the core) that can create heating in the
transformer, which, if sufficiently high and of long duration, can lead to
overheating and reduction of a transformer’s life;
 increased reactive power consumption that can cause the system to collapse due
to voltage instability;19 and
 damage and upset of customer equipment due to power quality disturbances.
In addition, GIC may cause harmonic damage to generator rotors and thermal damage to static
VAR compensators that provide reactive power to the grid, according to industry sources.20
The CISR Framework and HEMP
The technical summary presented above is a simplification of complex phenomena that are the
subjects of continuing scientific research programs across numerous disciplines and sub-
disciplines. The degree (and policy relevance) of scientific uncertainty is itself a significant
source of disagreement among stakeholders in the national critical infrastructure security and
resilience (CISR) enterprise. Industry stakeholders generally wish to avoid what some see as
costly mandates to invest in unproven technologies based on limited scientific research, while
some policymakers and advocacy groups believe the existing knowledge and technological bases
are sufficient to justify an expansive hardening program across vulnerable critical infrastructure
sectors.21
Industry adoption of EMP-hardened equipment in the electricity sector is market-driven in the
United States. Equipment manufacturers may choose from among available hardening standards
or specify their own proprietary testing criteria if they wish to make EMP resilience part of their

18 For example, see DOE, Division of Infrastructure Security and Energy Restoration, Geomagnetic Disturbance
Monitoring Approach and Implementation Strategies, Washington, DC, January 2019, p. 3.
19 Apparent power of a given AC system is a function of reactive power measured in Volts-Amps Reactive (VAR) used
for voltage support, and active power used for lighting, heating, operation of machinery, and other useful work.
Consumers are typically billed for active power. For a summary description, see Federal Energy Regulatory
Commission, Reliability Primer, Washington, DC, p. 18, https://www.ferc.gov/sites/default/files/2020-04/reliability-
primer_1.pdf.
20 See ABB Inc., SolidGround Grid Stability and Harmonics Mitigation System, Mount Pleasant, PA, 2015, p. 3,
https://search.abb.com/library/Download.aspx?DocumentID=2GNM110098.
21 For discussion of industry perspectives on costs, see Government Accountability Office (GAO), Critical
Infrastructure Protection: Electricity Suppliers Have Taken Actions to Address Electromagnetic Risks, and Additional
Research Is Ongoing, GAO-18-67, Washington, DC, February 7, 2018, pp. 47-50; and Maj. David Stuckenberg, op cit.,
p. 7. Stuckenberg suggests that EPRI focused its EMP research on areas of grid operations (transmission and sub-
station components) with strongest chances for early cost recovery of any mitigation investments. The North American
Electric Reliability Corporation (NERC), the industry-led electric reliability organization for the bulk power system,
stated in testimony to Congress in 2012 that HEMP events were acts of war and therefore defense against them was a
federal responsibility. See U.S. Congress, House Committee on Homeland Security, Subcommittee on Cybersecurity,
Infrastructure Protection, and Security Technologies, The EMP Threat: Examining the Consequences, Statement of the
North American Reliability Corporation, 112th Cong., 2nd sess., September 12, 2012.
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product marketing.22 In some cases, manufacturers have also advertised the successful use of their
equipment in testing by federal agencies or federally-sanctioned industry reliability
organizations.23 Companies may self-certify or seek third-party certification from an accredited
body to indicate compliance with specific standards. Electricity producers may then decide
whether the cost premium for hardened equipment is justified, given their specific risk profiles
and tolerances.
Because much of the nation’s critical infrastructure is owned and operated by the private sector
on a for-profit basis, implementation of federal initiatives to counter known threats to
infrastructure, including HEMP, often depends on industry engagement in public-private
partnerships for resilience. Such engagement may involve sharing potentially sensitive
information with government and non-government stakeholders, investing in research, and
making relevant resilience investments based on available risk assessments and protection
standards. These investments may involve significant up-front business costs that must be
absorbed or passed to customers.
Federal initiatives to increase infrastructure resilience to HEMP hazards—often in response to
congressional mandates or executive branch directives—have generally assumed the voluntary
public-private partnership model as the basis for programs and activities. There is no federal
regulatory requirement for hardening of critical infrastructure against HEMP.24 Likewise, there is
no relevant reporting requirement or centralized database containing information about industry
adoption of hardening measures. However, the Department of Homeland Security (DHS)
administers voluntary protected disclosure programs.25 According to some observers, private-
sector investment in HEMP resilience has generally been uneven and limited.26
Under the current regulatory framework, the federal government oversees reliability for the
generation and transmission systems of the electric power sector. These components comprise the

22 For an overview of standards and their application to EMP protection, see William A. Radasky, “Protecting Industry
from HEMP and IEMI,” In Compliance: Electronic Design, Testing & Standards, October 31, 2018,
https://incompliancemag.com/article/protecting-industry-from-hemp-and-iemi/.
23 ABB Inc., ibid., p. 6, https://search.abb.com/library/Download.aspx?DocumentID=2GNM110098.
24 NERC has issued standards for transmission operators to have GMD operating plans in place, to counter effects of
space weather events. Such plans rely upon space weather forecasting and advance warning of major GMD events.
These standards do not apply to manmade events that may occur with little or no notice, such as HEMP E3, and do not
mandate specific equipment hardening measures. See DOE, Division of Infrastructure Security and Energy Restoration,
Geomagnetic Disturbance Monitoring Approach and Implementation Strategies, Washington, DC, January 2019, pp. 6-
7.
25 DHS administers the Protected Critical Infrastructure Information (PCII) program under authorities of the Critical
Infrastructure Information Act of 2002 (Title II, Subtitle B, of P.L. 107-296) to encourage industry sharing of sensitive
critical infrastructure information in exchange for confidentiality and limited immunities against regulatory action,
involuntary disclosure to third parties, and litigation.
26 For example Chris Beck, Eric Easton, and Carl Eng, et al., Electric Infrastructure Protection Handbook IV:
Electromagnetic Pulse Protection Best Practices (the EIS study), the Electric Infrastructure Security (EIS) Council,
Washington, DC, January 1, 2021, p. 18; also DOE, Division of Infrastructure Security and Energy Restoration,
Geomagnetic Disturbance Monitoring Approach and Implementation Strategies, Washington, DC, January 2019, p. 12;
and Government Accountability Office (GAO), Critical Infrastructure Protection: Electricity Suppliers Have Taken
Actions to Address Electromagnetic Risks, and Additional Research Is Ongoing, GAO-18-67, Washington, DC:
February 7, 2018. According to the GAO report, only 3 of 11 electricity suppliers who responded to GAO enquires
about HEMP resilience activities reported having studied possible network impacts of HEMP events. See also the
Commission to Assess the Threat to the United States From Electromagnetic (EMP) Pulse Attack, Assessing the Threat
From Electromagnetic Pulse, Executive Report (EMP Commission Executive Report), Washington, DC, July 2017, pp.
6-8, http://www.firstempcommission.org/uploads/1/1/9/5/119571849/
executive_report_on_assessing_the_threat_from_emp_-_final_april2018.pdf.
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bulk power system. The Energy Policy Act of 2005 (EPACT05; P.L. 109-58) authorized the
Federal Energy Regulatory Commission (FERC) and its certified electric reliability organization,
the North American Electric Reliability Corporation (NERC), to develop and enforce mandatory
reliability standards for the bulk power system.27
In most cases, state and local authorities regulate local distribution systems and retail sales to
customers, and may also mandate relevant reliability standards or specific risk mitigation
activities. Federal or state regulatory authorities may allow for cost-recovery—i.e., passing costs
of regulatory compliance on to customers. Alternatively, Congress or state legislatures may
provide grants or otherwise direct relevant regulatory agencies to force utilities to absorb these
costs.
Strategies, Plans, Policies, and Legislation
A variety of strategies, plans, policies, and legislation have guided federal efforts to understand
and manage HEMP-related risks in recent decades.
Agency Strategies and Action Plans
In 2015, the Secretary of Energy directed DOE to develop an EMP resilience strategy (the DOE
Joint Strategy) in coordination with the electric power industry through EPRI. DOE described the
Joint Strategy, released in 2016, as “a public-private collaborative effort, designed to establish a
common framework with consistent goals and objectives that will guide both government and
industry efforts to increase grid resilience to EMP threats.”28
The DOE Joint Strategy identified five goals:
1. improve and share understanding of EMP threat, effects, and impacts;
2. identify priority infrastructure;
3. test and promote mitigation and protection approaches;
4. enhance response and recovery capabilities to an EMP attack; and
5. share best practices across government and industry, nationally and
internationally. An action plan based on the strategy was released in 2017.29

In 2018, DHS released an EMP/GMD strategy (the DHS strategy) in fulfilment of a congressional
mandate enacted by Section 1913 of the National Defense Authorization Act for 2017 (FY2017
NDAA; P.L. 114-328).30 The strategy identified three main goals:

27 For an overview of federal reliability requirements and regulatory framework, see CRS Report R45764, Maintaining
Electric Reliability with Wind and Solar Sources: Background and Issues for Congress, by Ashley J. Lawson,
especially the section “Electric Reliability Regulatory Framework.”
28 DOE and EPRI, Joint Electromagnetic Pulse Resilience Strategy: A Collaborative Effort of the U.S. Department of
Energy and the Electric Power Research Institute, Washington, DC, July 2016, https://www.energy.gov/sites/prod/
files/2016/07/f33/DOE_EMPStrategy_July2016_0.pdf.
29 DOE, U.S. Department of Energy Electromagnetic Pulse Resilience Action Plan, Washington, DC, January 2017,
https://www.energy.gov/sites/prod/files/2017/01/f34/
DOE%20EMP%20Resilience%20Action%20Plan%20January%202017.pdf.
30 Department of Homeland Security, Strategy for Protecting and Preparing the Homeland Against Threats of
Electromagnetic Pulse and Geomagnetic Disturbances, Washington, DC, October 9, 2018, https://www.dhs.gov/sites/
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1. improve risk awareness of electromagnetic threats and hazards;
2. enhance capabilities to protect critical infrastructure from the impact of an
electromagnetic incident; and
3. promote effective electromagnetic-incident response and recovery efforts. DHS
indicated that the strategy will remain in effect until 2026 and be updated every
two years thereafter.31

The EMP Commission
Congress first established the Commission to Assess the Threat to the United States from
Electromagnetic Pulse Attack (EMP Commission) under Title XIV of the Floyd D. Spence
National Defense Authorization Act (NDAA) for Fiscal Year 2001 (P.L. 106-398). It was
reestablished under Section 1052 of FY2006 NDAA (P.L. 109-163). Section 1075 of the FY2008
NDAA (P.L. 110-181) modified the EMP Commission’s authorities, extending the deadline for
previous reporting requirements among other provisions. The EMP Commission was
reestablished for a second time under Section 1089 of the FY2016 NDAA (P.L. 114-92). Section
1691 of the FY2018 NDAA (P.L. 115-91) established a new EMP Commission to complete
another assessment and report due April 1, 2019, but the provision was subsequently repealed by
Section 1695 of the FY2020 NDAA (P.L. 116-92).
The EMP Commission released several reports under these authorizations, with the final report
being published in July 2017. EMP Commission members have generally presented HEMP risk to
critical infrastructure as posing an existential threat to the United States—a position that appears
to have informed policy in some instances. According to a former senior Commission staff
member, the EMP Commission informed development of Executive Order (E.O.) 13865,
“Coordinating National Resilience to Electromagnetic Pulses,” which—he claimed—sought to
implement the EMP Commission’s core recommendations “on an accelerated basis.”32
Executive Order (E.O.) 13865 and the FY2020 NDAA
Table 2 summarizes EMP resilience provisions in Section 1740 of the National Defense
Authorization Act for Fiscal Year 2020 (FY2020 NDAA; P.L. 116-92) derived from E.O. 13865,
and the current status of mandated programs and activities.33 In 2020, DHS published an update
on steps taken to comply with E.O. 13865, and indicated it would conduct additional vulnerability
testing of “prioritized critical infrastructure components” and validation testing of mitigation
options “as funding becomes available.”34

default/files/publications/18_1009_EMP_GMD_Strategy-Non-Embargoed.pdf.
31 Ibid., p. 5.
32 Peter Pry, “Finally, a Presidential EMP Order That May Save American Lives,” The Hill, March 28, 2019,
https://thehill.com/opinion/national-security/436224-finally-a-presidential-emp-order-that-may-save-american-lives/;
and Executive Office of the President, “Coordinating National Resilience to Electromagnetic Pulses,” 84 Federal
Register 12041, March 26, 2019, https://www.federalregister.gov/d/2019-06325.
33 The Cybersecurity and Information Security Agency, a DHS agency, maintains an EMP/GMD information page with
an overview of departmental activities and program updates at https://www.cisa.gov/emp-gmd.
34 Department of Homeland Security, Electromagnetic Pulse (EMP) Program Status Report, August 17, 2020, p. 3,
https://www.cisa.gov/sites/default/files/publications/emp-program-status-report_508.pdf.
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Table 2. EMP/GMD-Related Requirements in FY2020 NDAA
Department or
Agency
Requirement
Deadline
Status
Agencies supporting
Update operational plans
March 20, 2020
DOE stated that its
National Essential
to protect against and
updated “response plans,
Functions
mitigate effects of
programs and procedures
EMP/GMD on critical
and operational plans all
infrastructure.
account for the effects of
EMP and GMD.”
DHS (with relevant
Conduct R&D to improve March 26, 2020
DHS developing EMP risk
sector risk management
EMP/GMD effects
models, and protection
agencies)
modeling and resilience-
and mitigation
enhancing technologies.
technologies for identified
Submit R&D Action Plan
high-risk infrastructure
to Congress to address
categories.
shortfalls.
DHS (with DOD, DOE,
Complete intelligence-
March 26, 2020
DHS refining risk models
DOC)
based Quadrennial Risk
to support completion of
EMP/GMD Assessment
initial quadrennial
(QRA) and brief to
assessment. Initial
Congress. Use results to
prioritization of “limited
increase critical
set of systems, networks,
infrastructure resilience,
and assets” complete,
prioritizing assets at
focusing on Energy and
greatest risk.
Communications sectors.
DHS
Distribute information on
June 19, 2020
Ongoing through existing
EMP/GMD to federal,
programs and activities.
state, local, and private
DHS may create program
sector stakeholders. Brief
office to guide public-
to Congress.
private engagements.
FEMA (with CISA, DOE,
Coordinate EMP/GMD
June 19, 2020
Ongoing compliance via
FERC)
response and recovery
existing plans and
plans and procedures.
procedures—e.g. FEMA
Power Out Incident
Annex, and DHS EMP
resilience guidelines.
DHS (with S&T, CISA,
Pilot test of engineering
September 22, 2020
Under contract with Los
FEMA, DOD, DOE)
approaches to mitigate
Alamos National
EMP/GMD effects on
Laboratory (LANL) for
critical infrastructure.
completion by July 2021.
DHS S&T released report
on EMP mitigation best
practices in August 2022.
DOD (with DHS, DOE)
Pilot test of engineering
September 22, 2020
Interagency pilot project
approaches to harden
in San Antonio, TX,
defense installations and
ongoing. Additional work
associated infrastructure.
pending completion of
LANL pilot test of
engineering approaches.
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Department or
Agency
Requirement
Deadline
Status
DHS (with sector-
Review test data on
December 20, 2020
No information provided.
specific agencies, DOD,
EMP/GMD effects on
DOE)
critical infrastructure to
identify gaps. Within 180
days of review, develop
integrated cross-sector
plan using public-private
partnerships to address
identified data gaps.
DHS (with DOD, DOE)
Report to Congress on
December 21, 2020
DHS developed
technological options to
technology scouting
increase critical
report for confidential
infrastructure resilience
distribution to federal
to EMP/GMD events and
agencies and designated
identify gaps and
private sector partners.
opportunities, with
Draft of report to
updates on quadrennial
Congress on
basis.
technological options in
review.
FEMA (with CISA, DOE,
Conduct EMP/GMD
December 21, 2020
Completed in December
FERC)
national exercise.
2020
DHS (with FEMA, CISA,
Report to Congress on
December 21, 2020
Vulnerability assessment
DOD, DOC, FCC, DOT)
effects of EMP/GMD on
of priority infrastructure
communications
ongoing (scheduled
infrastructure with
completion July 2021).
recommendations for
Report was expected
changes to operational
January 2022.
response plans.
FEMA
Maintain relevant
December 21, 2020
Complied via briefing to
emergency alerting
House Energy and
systems. Brief Congress
Commerce Committee
on state of emergency
on November 2, 2020.
notification systems.
FEMA has hardened some
key emergency
communications facilities.
Source: FY2020 NDAA (P.L. 116-92), Section 1740; email correspondence on March 8, 2021, with James Platt,
Strategic Defense Initiatives, EMP/PNT/GMD Space Weather/Space Risks, National Risk Management Center,
CISA; Department of Homeland Security, Electromagnetic Pulse (EMP) Program Status Report, August 17, 2020,
and CRS search of public sources, 2022.
Notes: The DHS strategy anticipated E.O. 13865, stating “wil adjust etc.” Parentheses in the first column
denote a coordination requirement for the lead department or agency (in bold). CISA = Cybersecurity and
Infrastructure Security Agency (a part of DHS); DHS = Department of Homeland Security; DOC = Department
of Commerce; DOD = Department of Defense; DOE = Department of Energy; DOT = Department of
Transportation; EMP = electromagnetic pulse; FCC = Federal Communications Commission; FEMA = Federal
Emergency Management Agency (a part of DHS); FERC = Federal Energy Regulatory Commission (an
independent regulatory commission within DOE); GMD = geomagnetic disturbance; R&D = research and
development; S&T = Science and Technology Directorate (a part of DHS).

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Not included in the FY2020 NDAA is the E.O. 13865 requirement for DHS and other federal
agencies to “identify regulatory and non-regulatory mechanisms, including cost recovery
measures” for private sector entities to address EMP risk.35
HEMP and Infrastructure Legislation in the 117th Congress
The IIJA contains several infrastructure resilience provisions that either explicitly include
addressing HEMP as a program consideration or implicitly allow addressing HEMP as part of an
all-hazards risk management approach. Other provisions confine funding to extreme weather,
wildfire, and natural disasters, but nevertheless may still affect HEMP resilience incidentally. For
general information on IIJA grid resilience provisions, see CRS Report R47034, Energy and
Minerals Provisions in the Infrastructure Investment and Jobs Act (P.L. 117-58), coordinated by
Brent D. Yacobucci.
IRA does not contain HEMP-specific provisions. However, changes in grid technology and
topology envisioned under the law—such as increased use of renewable energy sources—may
affect HEMP resilience incidentally. For general information on relevant IRA programs, see CRS
Report R47262, Inflation Reduction Act of 2022 (IRA): Provisions Related to Climate Change,
coordinated by Jane A. Leggett and Jonathan L. Ramseur.
HEMP-Specific Provisions in the IIJA
Section 40125(d), “Modeling and Assessing Energy Infrastructure Risk,” authorized $50 million
over five years for creation of an “advanced energy security program” within DOE to support
modeling of risks to energy networks posed by natural and human-made threats and hazards,
“including electromagnetic pulse and geomagnetic disturbance.”36 EMP and GMD are the only
hazards specifically named under this provision. Examples of eligible activities include
development of new capacities to identify vulnerable grid components, research on grid
hardening solutions, research mitigation and recovery solutions, grid resilience exercises and
assessments, and “technical assistance to States and other entities for standards and risk analysis.”
Section 40103(d), “Energy Infrastructure Resilience Framework,” directs the Secretary of Energy,
in collaboration with the Secretary of Homeland Security, FERC, NERC, and “interested energy
infrastructure stakeholders,” to research options for building and stockpiling portable replacement
LPTs. In 2017, DOE published a plan in compliance with a similar congressional mandate
enacted under Section 61004 of the Fixing America’s Transportation Act (P.L. 114-94) to
establish a strategic transformer reserve in partnership with industry stakeholders.37
Section 40321, under Subtitle C, “Nuclear Energy Infrastructure,” requires DOE to submit a
report to Congress on micro and small nuclear reactors. The mandated report must describe how
the department could enhance energy resilience of DOE facilities and remote communities using
micro-reactors and small modular reactors, and include an assessment of how such installations

35 Federal Register, op cit., p. 12045.
36 Division J of IIJA appropriated funds for this and certain other programs listed in this report. For appropriations
information on IIJA energy sector programs, see CRS Report R47034, Energy and Minerals Provisions in the
Infrastructure Investment and Jobs Act (P.L. 117-58), coordinated by Brent D. Yacobucci.
37 Department of Energy, Strategic Transformer Reserve, Report to Congress, Washington, DC, March 2017,
https://www.energy.gov/sites/default/files/2017/04/f34/Strategic%20Transformer%20Reserve%20Report%20-
%20FINAL.pdf.
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might address the “need for protection against cyber threats and electromagnetic pulses,” among
other threats and hazards.
IIJA appropriated $157.5 million under the “Science and Technology Directorate, Research and
Development” heading, available until September 30, 2026, to the DHS Science and Technology
Directorate (S&T) for CISR-related “research, development, test, and evaluation.” EMP and
GMD resilience capabilities were one of five named eligible categories for use of funds.38
Other Potentially Relevant IIJA Grid Resilience Provisions
Section 40101, “Preventing Outages and Enhancing the Resilience of the Electric Grid,”
authorized $5 billion in grant programs for electricity infrastructure owners and operators to
protect the grid against “disruptive events”—defined as extreme weather, wildfire, or natural
disaster occurrences that result in preventive or accidental outages, or hazardous safety
conditions. Eligible activities include construction of microgrids and battery storage equipment,
installation of adaptive protection technologies, replacement of power lines and underground
cables, and hardening of power lines, facilities, substations, and other systems.
Section 40102, “Hazard Mitigation Using Disaster Assistance,” amended the Robert T. Stafford
Disaster Relief and Emergency Assistance Act (Stafford Act; 42 U.S.C. 5170c (f)(12)) to make
installation of fire-resistant wires and undergrounding of wires eligible for Stafford Act funding.
(Undergrounding wires may provide some attenuation of HEMP hazards; see the
“Undergrounding Electrical Equipment and Power Lines” section.)
Section 40103 authorized $5 billion to support a new DOE program, “Upgrading Our Electric
Grid and Ensuring Reliability and Resilience,” which would offer competitive grants for states,
tribes, local governments, and public utility commissions. Grants would fund technology
demonstration projects related to resilience and reliability of the electric grid. The provision does
not name specific threats or hazards. As of this writing, DOE has issued a request for information
seeking information from stakeholders and a draft funding opportunity announcement.39
Section 40106, “Transmission Facilitation Program,” authorized programs to increase
transmission capacity, connect isolated microgrids to infrastructure, and support adoption of
advanced technologies to increase “capacity, efficiency, resiliency, or reliability of an electric
power transmission system.”
Section 40107, “Deployment of Technologies to Enhance Grid Flexibility” authorized $3 billion
in funds for the DOE Smart Grid Investment Matching Grant Program. Authorized activities
include buildout of fiber and wireless broadband communication networks, and advanced
transmission technologies and sensors, to enable better coordination of grid operations and
enhance grid flexibility. (This includes the ability to island sections of the grid to isolate against
cascading grid failures in case of extreme weather and nature disasters.) Grid flexibility is a
power system’s capacity to dynamically balance power supply with demand across a wide area
using networked systems of electricity generation, transmission, and distribution.

38 The other four categories were (1) special event risk assessments rating planning tools; (2) positioning, navigation,
and timing capabilities; (3) public safety and violence prevention to evaluate soft target security, including countering
improvised explosive device events and protection of U.S. critical infrastructure; and (4) research supporting security
testing capabilities relating to telecommunications equipment, industrial control systems, and open source software.
39 See DOE, “Program Upgrading Our Electric Grid and Ensuring Reliability and Resiliency,” https://www.energy.gov/
bil/program-upgrading-our-electric-grid-and-ensuring-reliability-and-resiliency.
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Section 40108, “State Energy Security Plans” amends the Energy Policy and Conservation Act of
1975 (P.L. 94-163; EPCA) to modify requirements for state energy security plans. Plans must
address all energy sources and providers, include a state energy profile, address cyber and
physical vulnerabilities, provide a risk assessment, and provide a risk mitigation approach, among
other requirements, in order to receive federal financial assistance under Part D of EPCA. The
program provides grants to support implementation of state energy plans.40 Congress appropriated
$500 million for formula grants to be awarded under the State Energy Program between FY2022
and FY2026.41
Section 40125, “Enhanced Grid Security,” authorizes $250 million over five years for
cybersecurity-related projects, and to support all-hazards based risk assessments of
communications, control systems, and power systems architectures used to operate the grid.
Additionally, it supports pilot projects with energy sector stakeholders to gain experience using
relevant emerging technologies.
Section 11105, “National Highway Performance Program,” allows for undergrounding “public
utility infrastructure” in conjunction with otherwise eligible transportation projects authorized
under the National Highway Performance Program (23 U.S.C. 119).
Research Issues
Issues of scientific theory, method, and analysis continue to be debated within the broader
research community in response to emerging HEMP research and related policy initiatives. To
date, research programs—each with its own objectives, assumptions, resources, and limitations—
have generally produced inconsistent or incomplete estimates of HEMP-related risks to
infrastructure. As such, existing research has failed to elicit broad industry consensus on the
methods, scale, and scope of any broad-based hazard mitigation program.
HEMP Environments and Benchmarks
Non-defense research generally relies upon a limited number of unclassified models of
electromagnetic hazard fields generated by HEMP—usually referred to as HEMP
environments—to assess the potential effects of high-altitude nuclear detonations. Unclassified
HEMP environments, such as the one represented graphically in Figure 2, provide the predicted
peak strength of hazard fields in a given location in relation to the blast epicenter based on a
generic waveform, but do not provide the fidelity needed to inform comprehensive and
authoritative risk assessments, according to researchers.
For example, the EPRI study states, “several unclassified E1 EMP environments exist, but in
general, these environments have limited usability because they are comprised of a single
waveform or ... provide a generic representation of the peak electric field on the ground,” and do
not include other important parameters, such as polarization of the electric field and angle of
incidence.42 Researchers must then make educated assumptions about these parameters in order to

40 See DOE, “State Energy Program Guidance,” https://www.energy.gov/eere/wipo/state-energy-program-
guidance#bipartisan; and National Association of State Energy Officials, NASEO’s State Energy Planning Guidelines:
Guidance for States in Developing Comprehensive Energy Plans and Policy Recommendations, Arlington, VA, 2018,
p. 18, https://naseo.org/Data/Sites/1/sepguidelines_2018_final.pdf.
41 DOE, State Energy Program Notice 22-03, Washington, DC, August 26, 2022, p. 2, https://www.energy.gov/sites/
default/files/2022-08/SEP_IIJA_Application_Instructions.pdf.
42 EPRI study, p. 2-1. See also Ross Guttromson, Craig Lawton, and Matthew Halligan, et al., Electromagnetic Pulse—
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predict effects on exposed infrastructure systems. (See the “Obstacles to Improved Risk
Management” section.) Detailed findings and data from classified EMP research are generally not
available outside the defense research community. In its final report, the EMP Commission
criticized Department of Defense (DOD) data classification policies and the “absence of
technology transfer and other support” to other agencies and critical infrastructure stakeholders.43
In a January 2021 memorandum, the Secretary of Energy released benchmark waveforms to
inform testing and predictive modeling by industry and government entities in fulfillment of E.O.
13865.44 The memorandum did not provide specific hardening standards or “specify the level of
risk critical infrastructure faces from HEMP.”45 As such, the Secretary presented it as “a first step
in a long conversation with civilian stakeholders to begin to understand the threat, consequence,
and risk associated with EMPs and how to address the risks.”46
The benchmark waveforms published in the memorandum were based on available unclassified
research from the International Electrotechnical Commission (IEC), Oak Ridge National
Laboratory (ORNL), and the EMP Commission. The provided peak field strengths for E1 and E3
electric fields were as follows:
 E1: 50 kV/m (Source: IEC)
 E3A: 80 V/km (Source: EMP Commission)
 E3B: 50 V/km (Source: IEC)
The DOE memorandum indicated that the benchmark values it provides were provisional, and
that testing against these benchmarks may “exceed DOE’s currently assessed threat levels by a
factor of 2 due to predictive modeling uncertainties and potential excursions in HEMP
environment levels.” Further, “The recommended E1, E2, and E3 HEMP environment benchmark
waveforms will be updated as necessary, based on further developments in our understanding of
HEMP generation and modeling and simulation phenomenology.”47
Modeling and Simulation of Infrastructure Resilience
Modeling and simulation are used to estimate risk levels to infrastructure in a given HEMP
environment. Although straightforward in principle, the integration of modeling, simulation, and
experimental testing of system components to identify and measure relevant risk factors is
complex in practice.

Resilient Electric Grid for National Security: Research Program Executive Summary, Sandia National Laboratories,
SAND2020-11227, Albuquerque, NM, October 2020, p. 11, for discussion of waveform limitations and research
implications. According to the study, available unclassified waveforms from IEC commonly used in non-military
HEMP risk assessments “lack additional details that, if included in the analysis, would often result in a lesser
consequence,” p.13. The report provides an overview of a three-year internally-funded research program to investigate
HEMP and the electric power grid that produced 23 reports and papers.
43 EMP Commission Executive Report, pp. 8- 9.
44 Dan Brouillette, Physical Characteristics of HEMP Waveform Benchmarks for Use in Assessing Susceptibilities of
the Power Grid, Electrical Infrastructures, and Other Critical Infrastructure to HEMP Insults, Department of Energy,
National Security Council Records, Washington, DC, January 11, 2021, https://www.energy.gov/sites/default/files/
2021/01/f82/FINAL%20HEMP%20MEMO_1.12.21_508.pdf.
45 Ibid., p. 1.
46 Ibid.
47 Ibid., p. 2.
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Modeling and simulation studies must account for one or more of the following:
 interaction of radiation and blast effects of the weapon with the natural
environment to produce HEMP hazard fields,
 interaction of HEMP hazard fields with exposed infrastructure systems and
assets, and
 secondary or cascading effects of such interactions on critical infrastructure
functions.
Researchers have used modeling and simulation to create and test synthetic electrical grids
against notional HEMP events, but—absent data on specific system topologies and other sources
of uncertainty—such tests can produce only general insights on grid behavior and failure
modes.48 According to EPRI, “Interconnection scale modeling requires a high-fidelity E1 EMP
environment (not publicly available) and ability to perform coupling calculations on 1000’s of
substations simultaneously.”49
Studies using a variety of research designs and methods have produced scientific advancement
and limited consensus in some areas. However, widely divergent results and assessments of
HEMP risk to critical infrastructure has highlighted a need for further research and
methodological advancement.
Summary of HEMP Research Results
Despite significant gaps, existing HEMP research has identified several issues of concern that E1
radiative and conductive threats both present hazards to unprotected DPR, DCS, and supervisory
control and data acquisition (SCADA) systems in control houses or generation facilities,
according to some studies.50 (Older electromechanical relays, which have largely been supplanted
by DPRs, have been found to be highly resistant to electromagnetic pulses.)51 However,
conductive threats generally present higher risk. Relatively simple (and inexpensive) mitigations,
such as use of shielding, grounding, and insulation of control lines, as well as modification of
control house design and materials, appear to significantly reduce—but not eliminate—
vulnerability to E1 hazards.52
LPTs may suffer physical damage from both E1 and E3 hazards, although estimates of likely
damage vary. The EMP Commission warned of LPT hotspot heating caused by E3 induced core
saturation and system harmonics on sufficient scale to render major grid interconnections
inoperable for months or longer. More recent studies by EPRI and ORNL predicted that such
losses would occur on a lesser scale and would likely not present a systemic hazard to grid
operations—assuming that control and communications systems remained operable, and other
grid equipment was undamaged.53

48 Brian Pierre, Daniel Krofcheck, and Matthew Hoffman, et al., Modeling Framework for Bulk Electric Grid Impacts
from HEMP E1 and E3 Effects, Sandia National Laboratories, EMP-Resilient Grid Grand Challenge: Task 3.1 Final
Report, Albuquerque, NM, January 2021, p. 35, https://www.osti.gov/servlets/purl/1764794.
49 Randy Horton, “EPRI Electromagnetic Pulse Research,” Presentation to NERC EMP Task Force Meeting,
Washington, DC, June 12, 2019, p. 8, https://www.nerc.com/pa/Stand/EMPTaskForceDL/EPRI%206-12-19.pdf.
50 For example, EPRI study, EMP Commission critical infrastructure report, and EIS study.
51 EMP Commission critical infrastructure report, p. 24.
52 For example, EPRI study, EMP Commission critical infrastructure report, and EIS study.
53 EPRI study, p. xi; and ORNL, op cit., p. 4.
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Several studies identify voltage collapse caused by E3B as being of generally greater concern
than heat damage to a large number of transformers.54 Experts predict that in the case of an
interconnection-scale voltage collapse, restoration would be a complex and lengthy process. Lack
of availability of utility-scale power adjacent to affected areas and functioning communications
between geographically dispersed system operators might pose significant challenges.55
The vulnerability of generation facilities to HEMP threats is a topic of concern. Preliminary field
testing of a working generation facility by EIS found that E1 threats “will likely disrupt or
damage typical power plants.”56 The EPRI report stated, “Additional research is needed to
evaluate the potential impacts of HEMP on generation facilities themselves,” and suggested
extending the existing mitigation framework for the transmission system to develop hardening
and mitigation options for generation facilities.57 Additionally, the increasing prevalence of
renewables may offer both additional resilience and potential vulnerabilities. These technologies
are rapidly evolving, and research on potential HEMP vulnerabilities is in its preliminary stages
(see the “Inverter-Based Resources” section).
The Foundation for Resilient Societies, a critical infrastructure resilience research and advocacy
organization, published a report in 2020 that highlighted vulnerabilities of communications
technologies used to control electricity generation, transmission, and distribution.58 For example,
non-conductive fiber optic lines used for communications between electricity grid substations
rely upon amplifier points—placed at roughly 80 mile intervals—and fiber transceivers at
substations and control rooms. Fiber optic amplifiers and transceivers are vulnerable to HEMP,
according to the report.59 Similar risk exists where grid operators use wireless communications to
control grid assets—often in inaccessible areas where fiber optic technology is cost-prohibitive.
Wireless communications assets, such as cell towers, are protected against routine
electromagnetic interference, but may be vulnerable to HEMP.60
Appendix A provides a summary of selected research products.
Emerging Science and Technology Policy Issues
Major infrastructure legislation enacted during the 117th Congress funds buildout of infrastructure
capacity, research and planning activities, risk management activities, and expanded use of
emerging renewable energy technologies in the electricity sector. As of this writing,
implementation of authorized programs is in its early stages, and any eventual impact on HEMP
resilience is unknown. The following sections highlight certain technologies supported via
congressional authorizations and appropriations enacted under IIJA and IRA (see “HEMP and

54 For example, Ross Guttromson, Craig Lawton, and Matthew Halligan, et al., op cit., p. 15.
55 EMP Commission critical infrastructure report, p. 31.
56 EIS study, p. 123.
57 EPRI study, 8-1; in 2019, EPRI announced new project to evaluate E1 EMP impacts to generation facilities. See
Edison Electric Institute, “EPRI EMP Report & Grid Security: Key Messages,” press release, April 2019,
https://www.eei.org/-/media/Project/EEI/Documents/Issues-and-Policy/EPRI-EMP-Report—Grid-Security—Key-
Messages.pdf, p. 2.
58 See David Winks, Protecting U.S. Electric Grid Communications from Electromagnetic Pulse, The Foundation For
Resilient Societies, Exeter, NH, May 2020.
59 Ibid., p. 4.
60 Ibid.
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Infrastructure Legislation in the 117th Congress” section) that may have implications for HEMP
resilience depending upon implementation policies.
Inverter-Based Resources
Wind, solar, fuel cells, and batteries make up an increasing share of power generation and supply
capacity. These power sources use inverters to convert the direct current electricity they produce
to alternating current electricity used by most electricity consumers. Wind resources are usually
implemented on utility-scale. Solar and battery resources may be implemented at utility-scale to
provide power for the grid, or may be used for rooftop and residential applications as distributed
energy resources (DERs). Hybrid approaches use digital control systems to combine DERs
operating as virtual power plants with grid-scale generation assets. Development and deployment
of such systems is in its early stages, as of this writing.61
The comparative advantages or disadvantages of distributed or hybrid generation using inverter-
based resources to provide energy and grid services during a HEMP event have not yet been
extensively researched.62
A 2022 National Renewable Energy Laboratory (NREL) study on hybrid power plants and grid
resilience suggested that “hybridizing or spatially distributing renewable energy generation
assets, the complementarity of the distinct resources can be leveraged to provide energy and grid
services more reliably than any of the assets can on their own.”63 However, it did not examine
potential effects of HEMP on inverter-based resources or associated electronic control systems
necessary to administer and provide operational control of hybrid power plants. The 2019 EPRI
report states that resilience of inverter-based generation against E1 hazards is unknown. Other
preliminary research indicates that photovoltaic panels are highly resistant to E1, but more testing
of connected inverters and associated electronic control systems is necessary.64
Inverter-based resources can provide ancillary services to the electricity grid such as voltage
support to help maintain stability if designed and configured appropriately.65 Electric vehicles—
essentially batteries on wheels—equipped with vehicle-to-grid (V2G) technology may provide
the same grid services, but the relevant technologies to automatically aggregate and coordinate
charging and power dispatch are still in the development and planning stages.66 Existing research
and development largely focuses on the routine application of battery storage and V2G

61 For example, see Miranda Wilson, “Northeast Embraces First-of-a-Kind Virtual Power Plant,” E&E News, October
12, 2022, https://www.eenews.net/articles/northeast-embraces-first-of-a-kind-virtual-power-plant/.
62 EPRI study, p. 4-25; and DOE, Wind Energy Technologies Office, “Wind Turbines Can Stabilize the Grid,” May 16,
20222, https://www.energy.gov/eere/wind/articles/wind-turbines-can-stabilize-grid.
63 Caitlyn E. Clark, Aaron Baker, and Jennifer King, et al., Wind and Solar Hybrid Power Plants for Energy Resilience,
National Renewable Energy Laboratory, NREL/TP-5R00-80415, Golden, CO, January 2022, p. 4,
https://www.nrel.gov/docs/fy22osti/80415.pdf.
64 See Tyler Bowman, Jack David Flicker, Ross Guttromson, et al., 2020, “High Altitude Electromagnetic Pulse
Testing of Photovoltaic Modules,” Sandia National Laboratory, Albuquerque, NM, https://doi.org/10.2172/1614961.
65 Malcolm Abbott and Bruce Cohen, “Issues Associated with the Possible Contribution of Battery Energy Storage in
Ensuring a Stable Electricity System,” The Electricity Journal, vol. 33, no. 6 (July 2020), pp. 1-6, and CRS Report
R45980, Electricity Storage: Applications, Issues, and Technologies, by Richard J. Campbell.
66 IIJA Sec. 40414 provides for data collection on electric vehicle integration with the electricity grids to further
research on V2G applications. For a technical discussion of relevant issues, see Jingyuan Wang, Guna R. Bharati, and
Sumit Paudyal, et al., “Coordinated Electric Vehicle Charging with Reactive Power Support to Distribution Grids,”
IEEE Transactions on Industrial Informatics, vol. 15, no. 1 (January 2019).
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technologies for maintaining grid stability. The utility of these technologies in a HEMP scenario
is largely unknown.
Microgrids
Microgrids may operate independently of the bulk electricity system if they are configured with
the appropriate hardware and software.67 Microgrids may be powered by a variety of power
sources and may offer some resilience to connected homes, businesses, and essential facilities
against large-scale outages caused by HEMP. However, microgrids—especially those intended for
civilian use—are not necessarily designed to withstand E1 pulses that may affect power control
systems and other sensitive electronics.68
Nonetheless, hardening microgrids against HEMP through the use of protective enclosures and
other measures may be more practical and less costly than for conventional grid assets.69
By definition, microgrids do not use long transmission lines and LPTs that form the backbone of
the electric grid, and so they do not have direct vulnerability to GMD caused by E3 when
operated independently of the grid. Some connected microgrids have the capability to disconnect
from major distribution networks and operate in “island” mode during an emergency in order to
avoid cascading effects of large-scale grid failures.
Transmission Facilitation and Grid Flexibility
For economic reasons, the existing electricity system operates with minimal redundancy and
spare capacity—a condition enabled by increased adoption of (potentially vulnerable) electronic
controls and other digital technologies in recent decades.70 Power grids are more vulnerable to
disruption when they operate with little spare capacity, according to experts.71 Increased
transmission capacity provides greater margins for grid operators to manage disruptions and
provide additional reactive power to maintain system voltages if necessary. A 2019 study by the
National Renewable Energy Laboratory predicted that considerable growth in electricity demand
due to anticipated electrification of residential heating and transportation (electric vehicles) would
“likely require grid capacity expansion and make grid operations and planning more
challenging.”72
Infrastructure programs to support increased transmission capacity and grid flexibility may
remediate these deficiencies to some degree. However, IIJA and IRA infrastructure programs to

67 According to DOE, “A microgrid is a group of interconnected loads and distributed energy resources within clearly
defined electrical boundaries that acts as a single controllable entity with respect to the grid. It can connect and
disconnect from the grid to enable it to operate in grid-connected or island-mode.” See Dan Ton, Microgrid R&D
Program at the U.S. DOE, Office of Electricity, Department of Energy, Washington, DC, November 2018, p. 3,
https://www.energy.gov/sites/prod/files/2018/12/f58/remote-microgrids-dan-ton.pdf.
68 See George H. Baker, “Microgrids—A Watershed Moment,” Insight, vol. 23, no. 2 (2020).
69 Barry Wilson, EMP Hardening with Electric Power Microgrids, Enviropower, Renewable Inc., Boca Raton, FL,
2019, p. 7, https://eprenewable.com/wp-content/uploads/2019/04/EMP_Hardening-with-Electric-Power-
Microgrids.pdf.
70 The EMP Commission, Report of the Commission to Assess the Threat to the United States from Electromagnetic
Pulse Attack, Critical National Infrastructures, Washington, DC, April 2008, p. 23.
71 Ibid., p. 17.
72 Michael Blonsky, Adarsh Nagarajan, and Shibani Ghosh, et al., “Potential Impacts of Transportation and Building
Electrification on the Grid: A Review of Electrification Projections and Their Effects on Grid Infrastructure, Operation,
and Planning,” Electrification, vol. 6, November 13, 2019, p. 169, https://link.springer.com/article/10.1007/s40518-
019-00140-5.
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facilitate integration of inverter-based resources and microgrids into the existing bulk electric
system focus on environmental performance—i.e., lower carbon dioxide emissions—and
resilience to extreme weather, wildfires, and natural disasters.
Future Grid Technologies and HEMP
Improvements in grid flexibility may enhance
the power system’s capacity to dynamically
New and emerging grid hardware technologies based
on semiconductor-based, solid state power converters
balance power supply with demand across a
may offer a number of broad resilience benefits,
wide area using networked systems of
according to DOE. The 2021 DOE technology
electricity generation, transmission, and
roadmap for solid state power substations (SPSS)
distribution during a HEMP event, if only
envisions replacement of existing analog grid substation
incidentally. However, potential operational
equipment with solid state technology.73
benefits and resilience of such prospective
Eventually, such systems might enable a grid that is
“ful y asynchronous, autonomous, and fractal”—i.e.,
systems to HEMP—many of which are still in
able to operate without frequency synchronization at
the research and development phase—are
the interconnection level; less reliant on long-distance
largely unknown.74 Loss of grid flexibility
communications networks for operational control; and
during a HEMP event may complicate efforts
able to rapidly isolate grid components to prevent
to manage disruptions and maintain
cascading failures.
functioning power supply. Existing HEMP
Solid state technologies may also help emergency
recovery by providing more portable and
research has largely focused on hazards to
interchangeable designs for major electric substation
conventional grid operations, rather than
components. Such grid technology features have long
inverter-based resources, microgrids, and
been of interest to the HEMP policy and research
advanced transmission technologies (see the
community, given the risks of system-level impacts
section “Modeling and Simulation of
from a HEMP event.
Infrastructure Resilience”).
However, successful commercialization of relevant
technologies may be decades away in some cases.
Additionally, their resilience to HEMP threats is largely
Undergrounding Electrical
unknown.
According to the DOE technology roadmap, “The
Equipment and Power Lines
ability to withstand electromagnetic interference (EMI)
and electromagnetic pulses [emphasis added] are . . areas
IIJA funds for undergrounding electrical
of investigation that wil need to span the entire
equipment and power lines are restricted to
converter architecture, including the control ers and
protection against extreme weather, wildfires,
communication subsystems.”
and natural disasters (see “Other Potentially
Relevant IIJA Grid Resilience Provisions”).
However, undergrounding certain assets to protect against these hazards may incidentally affect
HEMP resilience. EPRI research showed that undergrounding control cables at substations
connected to DPRs provided significant equipment protection against simulated E1 pulses.75 In
the case of buried long-distance transmission lines, conductive earth may attenuate early-time E1
pulses—lessening any coupling hazards to the grid. However, undergrounding long-distance
transmission lines would not prevent GIC caused by E3 magnetohydrodynamic effects, which
propagate through conductive geologic formations underground and enter the grid through
transformer groundings.

73 See Department of Energy, Office of Electricity, Solid State Power Substation Technology Roadmap, Transformer
Resilience and Advanced Components Program, Washington, DC, June 2020, p. 31, https://www.energy.gov/oe/
downloads/solid-state-power-substation-technology-roadmap.
74 Ibid., p. 31.
75 EPRI study, p. 4-10.
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Issues for Congress
As of this writing, DHS and other relevant federal agencies continue to implement legislative
mandates contained in the FY2020 NDAA, which legislate many of the directives contained in
E.O. 13865 (see the “Executive Order (E.O.) 13865 and the FY2020 NDAA” section). Major
outstanding items include DHS risk models for critical infrastructure and associated risk
assessments, engineering approaches for risk mitigation, and identification of emerging EMP
protection technologies. Many mandated deadlines have already passed. Documents submitted by
other agencies in compliance with E.O. 13865, such as the DOE memorandum on HEMP
waveforms (see the “HEMP Environments and Benchmarks” section) present data from existing
sources that are more than a decade old in some cases, and contain caveats indicating uncertainty.
It is not clear that existing HEMP research is sufficiently mature for DHS, or any other federal
agency, to provide authoritative guidance to policymakers or industry stakeholders on
prioritization of critical systems and assets for hardening or other countermeasures in the near
future. DHS has indicated more funding would be necessary to support necessary research (see
the “Executive Order (E.O.) 13865 and the FY2020 NDAA” section). IIJA appropriations to
federal agencies may support further research, depending upon how funds are apportioned to
specific research programs by implementing agencies (see the “HEMP-Specific Provisions in the
IIJA” section).
In all these potential HEMP-related issues, the appropriate roles for federal agencies, states, and
the private sector would be fundamental areas for congressional consideration.
Obstacles to Improved Risk Management
Researchers consistently identify issues with the underlying quality of data used to model HEMP
risk to critical infrastructure (see the “HEMP Environments and Benchmarks” section) as an
obstacle to providing more authoritative risk assessments to critical infrastructure stakeholders.
The EMP Commission and others have suggested that improved access to DOD and
DOE/National Nuclear Security Administration data and research on electromagnetic effects of
nuclear weapons, and selective declassification of certain data and research, might reduce such
obstacles, if only to a degree. Congress may consider legislating parameters and specific
objectives of interagency cooperation between DOD, DHS, DOE, and other relevant federal
agencies, and provide funding and oversight as appropriate.
Researchers also note the need for more detailed modeling of underground geologic formations
that play a role in propagation of E3 related hazards, and more detailed knowledge of specific
infrastructure topologies that affect system-level resilience to HEMP (see the “Modeling and
Simulation of Infrastructure Resilience” section). The U.S. Geological Survey, an agency of the
Department of the Interior, administers a geomagnetism program that supports the National Space
Weather Strategy, which focuses on naturally occurring electromagnetic hazards similar to
manmade E3. The program received increased funding under the FY2020 appropriations act to
continue a national magnetotelluric survey started by other federal agencies.76 Congress may
consider exercising oversight and other authorities to ensure relevant findings are available to the
HEMP research community.
Similarly, Congress may consider exercising oversight of existing DHS administered partnerships
with critical infrastructure stakeholders for protected critical infrastructure information disclosure

76 See CRS In Focus IF11181, The U.S. Geological Survey (USGS): FY2020 Appropriations Process and Background,
by Anna E. Normand.
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and information sharing, such as the Protected Critical Infrastructure Information program, which
may assist DHS in completing HEMP risk management activities mandated by the FY2020
NDAA (see the “The CISR Framework and HEMP” section).
Incentivizing and Facilitating Investment in HEMP Resilience
E.O. 13865 contemplates future introduction of cost-recovery mechanisms (such as increased
consumer electricity rates) that certain electricity providers could use to fund HEMP resilience
investments. In September 2022, FERC released a Notice of Proposed Rulemaking (NOPR) to
provide “incentive-based rate treatment” for utilities that invest in “advanced cybersecurity
technology” and participate in cybersecurity threat information sharing programs, pursuant to
Congress’s instructions in IIJA.77 The NOPR suggests certain cost-recovery mechanisms that may
be further elaborated during the rulemaking process. Congress may wish to direct FERC to
develop a similar rule to incentivize investment in HEMP resilience. Development and
implementation of such a rule might depend in part on availability of improved risk models, risk
assessments, and mitigation technologies as described above.
Congress may consider exercising oversight of development and implementation of State Energy
Security Plans described in Section 40108 of the IIJA (see the “Other Potentially Relevant IIJA
Grid Resilience Provisions” section) to ensure that HEMP resilience considerations are included
as deemed appropriate. DOE administers the program at the federal level and reviews and
approves individual state plans based on compliance with IIJA statutory requirements.78
Any congressional action would take place in a rapidly changing technology environment as grid
modernization and hardening initiatives authorized under IIJA, IRA, and other legislation
proceed, offering both opportunities and risk to policymakers (see the “Emerging Science and
Technology Policy Issues” section). Inverter-based energy resources and microgrids may
contribute to grid resilience against HEMP threats if they are appropriately configured and
located to provide grid services, such as voltage support, and are able to survive the HEMP
environment. Congress may consider supporting relevant research and development activities
through legislation, oversight, and appropriations.
Relevant (functionally identical) technologies may be more or less resilient to HEMP, depending
on what technical standards are applied to their design and manufacture, and their system
configuration. Existing legislation primarily contemplates resilience to extreme weather hazards,
wildfire, and other natural disasters as design considerations (see the “HEMP and Infrastructure
Legislation in the 117th Congress” section). Congress may consider explicit inclusion of HEMP
resilience in future infrastructure or related grants legislation. Additionally, Congress may
consider directing FERC to oversee development and implementation of infrastructure protection
standards specific to HEMP if deemed necessary (see “The CISR Framework and HEMP”
section).

77 See FERC, “FERC Proposes Incentives for Voluntary Cybersecurity Investments,” https://www.ferc.gov/news-
events/news/ferc-proposes-incentives-voluntary-cybersecurity-investments. For a summary of existing threat
information sharing programs, see CRS In Focus IF12061, Critical Infrastructure Security and Resilience: Countering
Russian and Other Nation-State Cyber Threats, by Brian E. Humphreys.
78 Department of Energy, Energy Efficiency and Renewable Energy Golden Field Office, Administrative and Legal
Requirements Document, Golden, CO, March 28, 2022, p. 11, https://www.energy.gov/sites/default/files/2022-03/sep-
state-energy-security-plan_alrd.pdf.
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Future Technological Advancements
Congress may consider future technological advancements when developing policies relevant to
HEMP resilience. For example, LPT stockpiling programs considered in the IIJA and previous
legislation assume existing transformer designs as the basis for operational control of electricity
transmission and distribution, which require large lead times for manufacture, customization, and
transport (see the “HEMP-Specific Provisions in the IIJA” section). Emerging solid state
technologies may enable a more rapid and flexible use of standardized systems to support a
building-block approach to construction and repair of grid infrastructure that would eliminate the
need for vulnerable LPTs. Likewise, such technology might enhance efficiency without
increasing risks to grid stability—an improvement over most existing technologies (see “Future
Grid Technologies and HEMP” text box, p. 20). Congress may consider balancing the need to
manage risks to existing infrastructure against the possibility of eliminating certain risks through
adoption of new technologies. Given the long service life of most electricity infrastructure assets,
it may be appropriate to encourage investment in next-generation technologies where possible to
avoid inefficient use of limited resources to harden obsolescent technologies against HEMP.
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Appendix A. Selected Studies by Year

Research
(year)
Research Design and Methods
Results and Conclusions
SANL (2021)
Modeling and simulation of E1 and E3 HEMP
Significant additional modeling and
hazards to notional bulk electric power grid.
simulation work on interaction of
(Effects of E3 harmonics not studied.) Use of
HEMP environment with grid
statistical methods and component testing results
infrastructure needed “to draw realistic
to quantify transient response of a modeled grid to
conclusions” on HEMP risk to
a HEMP event (IEC waveform), including cascading
infrastructure.
effects of E1 and E3.
SANL (10/2020) Study of conductive threat effects of simulated E1
Average maximum voltages on
HEMP events (using IEC waveform) on transmission overhead transmission lines were lower
lines and grid equipment control lines. Modeling and than the “typical worst case.” Induced
simulation to predict the effects of location and
voltage on these lines was, on average,
orientation of conductors relative to HEMP source
about 55% of the anticipated maximum
on induced current and voltage, and produce
value for a worst-case scenario for a
statistics on peak value, rise time, and pulse width
given line orientation.
at a given location.
SANL (9/2020)
Testing of electric power substation circuits and
“No equipment damage or undesired
certain protective equipment against simulated E1
operation occurred on the tested
insult. Injection of simulated E1 pulse into three
circuits for values below 180 kV, which
different types of circuits (breaker, potential
is significantly higher than the
transformer, and current transformer) connecting
anticipated [E1] coupling to a
digital protective relays (DPRs) in a control house
substation yard cable.”
with substation yard equipment.
SANL (4/2020)
Testing of photovoltaic (PV) modules against
“No direct failures” of PV modules and
simulated E1 insult to 100 kV/m benchmark. Does
only “minor observable module
not include testing of inverter systems used to
degradation” fol owing exposure.
convert direct current (DC) to alternating current
Testing of inverter systems against
(AC).
observed coupled currents planned for
future research.
EIS/SARA
DPR and distributed control system (DCS)
Unprotected DPRs and DCS
(2020)
components subjected to pulsed electric fields and
components were susceptible to
pulsed current injection to limits specified by
simulated HEMP insults. Simple
military standard (MIL-STD) 188-125. Working
remediation significantly mitigated risk.
generating station exposed to simulated HEMP
Generation station DCS and generator
hazard fields. Strength of subcomponents tested or
exciter systems are potential y
evaluated based on vendor documentation.
vulnerable. Generation facility easily
penetrated by simulated E1 fields.
EPRI (2019)
Commonly used DPRs subjected to simulated E1
Conductive E1 threats pose significant
pulsed electric fields and pulsed current injection
threat to unprotected DPRs. Simple
based on MIL-STD-188-125 (up to 50 kV/m).
remediation significantly mitigates risk.
Shielding effectiveness tests of typical substation
E3B may produce regional blackouts
control houses and mitigation devices.
due to voltage instability. Wide-scale
Interconnection-level assessments of E1 effects
LPT heat damage limited. Recoverable,
based on LANL (25 kV/m) and IEC 61000-2-9 (50
assuming limited harmonic effects, and
kV/m) E1environments, and E3B effects based on
adequate E1 protection of DPRs, DCS,
LANL HEMP environment and predicted reactive
and communications.
power losses. Effects of harmonics not studied.
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Ensuring Electricity Infrastructure Resilience Against Electromagnetic Pulse Threats

Research
(year)
Research Design and Methods
Results and Conclusions
ORNL (2019)
Assessment of system-wide impact to LPTs of
E1 may cause rapid voltage surges on
voltage surges and harmonics caused by HEMP or
long power lines, bypassing arresters
GMD. Pulsed electric fields based on IEC E1
designed to protect LPTs. Risk
benchmark for stress test of voltage arresters and
mitigated in some cases by modification
bushings to validate modeling. Computational
of system topology and use of updated
analysis of E1 and E2 effects on transformer
LPT designs. E3 is a “reduced risk
windings. E3 effects modeling based on actual grid
event.” Voltage stability is maintained
topology to predict GIC impacts on LPT core
even with significant loss of reactive
saturation and harmonics generation. Impact of
compensation units. GIC-blocking
GIC-blocking devices on grid stability simulated.
devices on LPTs are best risk-mitigation
option.
EMPC (2017)
Analysis of E3 fields created by two Soviet tests in
Recommended E3 field strength
1962. Infrastructure modeling and simulation from
benchmark of 85 V/km for testing
2008 study. Protective relays, DCS, and supervisory purposes. SCADA and—to lesser
control and data acquisition (SCADA) systems
degree—DCS most vulnerable. DPRs
exposed to simulated E1insults via free-field
comparatively robust. Wide scale and
il umination and cable current injection. Expert
long-lasting grid col apse likely in many
assessment of likely cascading effects of entire
scenarios.
HEMP sequence, and restoration considerations.
Sources: Brian Pierre, Daniel Krofcheck, and Matthew Hoffman, et al., Modeling Framework for Bulk Electric Grid
Impacts from HEMP E1 and E3 Effects, Sandia National Laboratories, EMP-Resilient Grid Grand Challenge: Task
3.1 Final Report, Albuquerque, NM, January 2021; Richard L. Schiek and Matthew Halligan, Statistical Profiles of E1
EMP Coupling to Single Conductors, Sandia National Laboratories, SAND2020-10738, Albuquerque, NM, October
2020; Alfred Baughman, Tyler Bowman, and Ross Guttromson, et al., HEMP Testing of Substation Yard Circuit
Breaker Control and Protective Relay Circuits, Sandia National Laboratories, SAND2020-9872, Albuquerque, NM,
September 2020; Tyler Bowman, Jack Flicker, and Ross Guttromson, et al., High Altitude Electromagnetic Pulse
Testing of Photovoltaic Modules, Sandia National Laboratories, SAND2020-3824, Albuquerque, NM, April 2020;
Chris Beck, Eric Easton, and Carl Eng, et al., Electric Infrastructure Protection Handbook IV: Electromagnetic Pulse
Protection Best Practices, the Electric Infrastructure Security (EIS) Council, Washington, DC, 2020; Electric Power
Research Institute (EPRI), High-Altitude Electromagnetic Pulse and the Bulk Power System: Potential Impacts and
Mitigation Strategies, Palo Alto, CA, April 2019; A.G. Tarditi, J.S. Besnoff, and R.C. Duckworth, et al., High-Voltage
Modeling and Testing of Transformer, Line Interface Devices, and Bulk System Components Under Electromagnetic Pulse,
Geomagnetic Disturbance, and Other Abnormal Transients, Oak Ridge National Laboratory, ORNL/TM-2019/1143,
Oak Ridge, TN, March 18, 2019; The Commission to Assess the Threat to the United States from
Electromagnetic (EMP) Pulse Attack, Assessing the Threat from Electromagnetic Pulse, Executive Report,
Washington, DC, July 2017.
Notes: EIS = EIS Council; EMPC = EMP Commission; EPRI = Electric Power Research Institute; ORNL = Oak
Ridge National Laboratory; SANL = Sandia National Laboratories; SARA = Scientific Applications and Research
Associates.

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Author Information

Brian E. Humphreys

Analyst in Science and Technology Policy

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