Nuclear High-Altitude Electromagnetic Pulse

A Mortal Threat to the U.S. Power Grid and U.S. Nuclear Power Plants

HEMP stands for High-altitude ElectroMagnetic Pulse (HEMP) created by a nuclear detonation above the atmosphere. While no blast, fires, or ionizing radiation will be experienced on Earth as a result of this detonation, a single HEMP will instantly create intense electromagnetic fields that will blanket tens or hundreds of thousands of square miles of the Earth’s surface.

The technology exists that can shield the grid and critical infrastructure from the effects of Electromagnetic Pulse (EMP). It would cost about 3% of what the US annually spends on its defense budget to provide this protection from EMP — but all efforts to mandate this protection have been defeated in Congress.

The following is a bullet point summary of the effects of a High-altitude Electromagnetic Pulse (HEMP) created by a single nuclear detonation from an altitude of roughly 19 miles to several hundred miles above the surface of the Earth.

— A single high-altitude nuclear detonation will create a massive Electromagnetic Pulse that will bring down much or all of the US national electric grid (and any national electric grid that has not been shielded from an Electromagnetic Pulse will also suffer the same consequences). The detonation does not have to occur in a precise location to have this effect; a detonation over Alabama, Indiana, or Ohio would wipe out the grid over most of the eastern half of the US, while a detonation over Nevada or Oregon would take out the grid in the western US. A detonation over the Yucatan Peninsula could take out the entire US power grid

— A nuclear weapon detonated at high-altitude over the continental US would create massive E1 waves in areas covering many tens of thousands of square miles beneath the detonation. In a few billionths of a second, the E1 component of HEMP can induce peak voltages of 2 million volts into long overhead medium-voltage power lines, which can create a current of 5000 to 10,000 amps in these lines.

— The extreme voltages and currents created by the E1 component of HEMP will damage/disable/destroy any unshielded solid-state electronics, which are found in all modern electronic devices. Those that are plugged in and connected to the grid will be most likely to be ruined, but in areas of intense levels of E1, even devices not connected to the grid can be damaged and destroyed.

— All critical national infrastructure relies on modern electronic devices to operate; most or all of the critical infrastructure in the affected areas will cease to function. All ground, sea, rail, and air transportation systems, fuel and food distribution systems, water and sanitation systems, telecommunication systems, and financial systems will be made inoperable. Emergency services and governmental services will be unavailable.

— E1 will also destroy tens of millions of insulators found on 15 kV power distribution lines, which deliver power to 78% of residences, farms, and industry. The loss of a single insulator can stop power distribution

— The E3 component from a single HEMP will cover all of continental US if the nuclear detonation occurs over Central America (E3A Blast Wave); this will damage or destroy most of the Large Power Transformers in the US national electric grid (which are required for the distribution of 90% of all electric power in the U.S.). It will also damage or destroy most of the Extra High Voltage Circuit Breakers,which will take months to repair and replace. If the detonation occurs over the Eastern or Western U.S., the E3B Heave Wave will have the same effects over each of those regions respectively; all of the Eastern or Western U.S. will be left without electricity for up to a year or longer.

— Current lead times for Large Power Transformers are 18 to 24 months (overseas suppliers); Large Power Transformers require custom design and very specialized manufacture. They typically weigh between 200 and 400 tons and are very difficult to ship, transport, and install. It would likely take more than a year to replace them; most of the US would be without electric power for a year or longer

— After the grid comes down, nuclear power plants will execute emergency shutdowns, but the massive voltages and currents induced by the E1 wave will disable their on-site power sources (Emergency Diesel Generators and Battery Banks). Consequently, there will be no electric power available to run the active Emergency Core Cooling Systems (ECCS). The active ECCS systems contain many motor-driven pumps, motor-operated valves, pressure and temperature sensors, and SCADA control units that will be disabled by E1, so even if power was available, they would not operate

— After emergency shutdown, the decay heat in the core of a nuclear reactor still creates 7% of the heat present when the nuclear reactor is operating at full power. In a large commercial nuclear reactor, hundreds of millions of megawatts of heat would still remain in the reactor core

— A failure of the active Emergency Core Cooling Systems to operate will cause the reactor core to melt down in as little as 30 minutes

–Spent fuel pools, which are adjacent to each nuclear reactor, each contain at least 3 to 5 times more radiation than does the reactor core; without a cooling system that constantly cools the pools, the water in the pools will boil off and allow the spent fuel rods to release massive amounts of radioactive materials that can leave an area the size of an entire state uninhabitable for centuries.

— Dozens of nuclear US power plants could be within the area where E1 is greater than 12,500 volts/meter. The massive voltages and currents created by the E1 wave will cause these nuclear reactors to simultaneously melt down

— As many as 50 nuclear power plants could melt down in France as a result of a single HEMP

— Shielding and technical fixes exist that can be used to protect the national electric grid and critical national infrastructure – including nuclear power plants – from HEMP/EMP  

— All efforts to mandate funding to protect the grid and critical infrastructure from HEMP/EMP have been blocked by electric and nuclear utilities, as well as the Nuclear Regulatory Commission, which maintains that EMP poses no danger to the nuclear power plants that it regulates.

Nuclear High-Altitude Electromagnetic Pulse: A Mortal Threat to the U.S. Power Grid and U.S. Nuclear Power Plants is now available on Amazon. Click on the book title above to go to the Amazon website to purchase the book or click on this link to go to Barnes & Noble. There also is an eBook (Kindle) version available, too.

Effects of a single high-altitude nuclear detonation over the Eastern U.S.

105 miles above Ohio, a single nuclear warhead explodes. Because it is far above the atmosphere, there will be no blast or fire effects felt on Earth, however, this high-altitude nuclear detonation will create a gigantic electromagnetic pulse or EMP. 

In one billionth of a second, the initial EMP E1 wave will cause massive voltages and currents to form within power lines, telecommunication lines, cables, wires, antennas, and any other electrically conductive material found beneath the nuclear detonation in a circular area covering hundreds of thousands of square miles. 

Within this region, under ideal conditions, the E1 wave will produce 2 million volts and a current of 5,000 to 10,000 amps within medium distribution power lines. Any unshielded modern electronic devices that contain solid-state circuitry, which are plugged into the grid, will be disabled, damaged, or destroyed. This includes the electronic devices required to operate all critical national infrastructure. 


Unshielded electronic devices within ground, air, and sea transportation systems, water and sanitation systems, fuel and food distribution systems, water and sanitation systems, telecommunication systems, and banking systems would all be simultaneously knocked out of service – and all these systems would be disabled until the solid-state electronics required to operate them could be repaired or replaced. 

The E1 wave will also instantly destroy millions of glass insulators found on 15 kilovolt-class electric power distribution lines. 78% of all electricity in the US is delivered to end users (residential, agricultural, commercial) through these 15 kV power lines. The loss of a single insulator on a line can knock out power distribution on the entire line.   

At the same instant, the massive voltage and current induced by the E1 wave will damage and destroy the relays, sensors, and control panels at 1783 High Voltage Substations, knocking out the entire electric power grid in the eastern half of the United States.  

One to ten seconds after the nuclear detonation, the following EMP E3 wave would induce powerful current flows in power lines including lines that are both above and below ground. E3 would damage or destroy many – if not most – of the Large Power Transformers and Extra High Voltage Circuit Breakers required for the long-distance transmission of about 90% of electrical power in the United States.  

The loss of Large Power Transformers and Extra High Voltage Circuit Breakers would mean that entire regions within the United States would be left without electric power for up to a year or longer. This is because Large Power Transformers are not stockpiled and the current wait time for their manufacture is 18 to 24 months; they must be custom designed and manufactured and about 80% are made overseas. They each weigh between 200 and 400 tons and must be shipped by sea and moving them to their final destination is quite difficult even under normal circumstances. 

Because nuclear power plants are not designed to withstand the effects of EMP, the solid-state electronics within their backup electrical and cooling systems would also be damaged and disabled. The failure of their Emergency Power Systems and active Emergency Core Cooling Systems will make it impossible to cool their reactor cores after emergency shutdown; this will quickly lead to reactor core meltdowns at dozens of nuclear power plants. 

To summarize, a single nuclear high-altitude electromagnetic pulse can instantly take out most or all of the US power grid while simultaneously destroying the solid-state electronic devices required to operate US critical national infrastructure – including the safety systems at nuclear power plants. Following a nuclear EMP, the people of the US would suddenly find themselves living in the conditions of the Middle Ages for a period possibly as long as a year – most Americans would not be able to survive such circumstances. 

For less than 4% of the US national defense budget, the US power grid and critical infrastructure can be shielded from EMP. However, the political will to implement this protection has not yet been found, so Americans remain very much at risk.       starrst@missouri.edu