How Would a Nuclear EMP Affect the Power Grid?

Late in the morning of April 28, 1958, the USS  Boxer aircraft carrier ship was about 70 miles   off the coast of the Bikini Atoll in the Pacific  Ocean. The crew of the Boxer was preparing to   launch a high-altitude helium balloon. In fact,  this would be the 17th high-altitude balloon to be   launched from the ship. But this one was a little  different. Where those first 16 balloons carried   some instruments and dummy payloads, attached to  this balloon was a 1.7 kiloton nuclear warhead,   code named Yucca. The ship, balloon, and  bomb were all part of operation Hardtack,   a series of nuclear tests conducted by the United  States in 1958. Yucca was the first test of a   nuclear blast in the upper limits of earth’s  atmosphere. About an hour and a half after the   balloon was launched, it reached an altitude of  85,000 feet or about 26,000 meters. As two B-36   peacemaker bombers loaded down with instruments  circled the area, the warhead was detonated. Of course, the research team collected  all kinds of data during the blast,   including the speed of the shock  wave, the effect on air pressure,   and the magnitude of nuclear radiation  released. But, from two locations on the ground,   they were also measuring the electromagnetic  waves resulting from the blast. It had been   known since the first nuclear explosions  that the blasts generate an electromagnetic   pulse or EMP, mainly because it kept frying  electronic instruments. But until Hardtack,   nobody had ever measured the waves generated from  a detonation in the upper atmosphere. What they   recorded was so far beyond their expectations,  that it was dismissed as an anomaly for years.   All that appears in the report is a casual mention  of the estimated electromagnetic field strength   at one of the monitoring stations being around  5 times the maximum limit of the instruments. It wasn’t until 5 years later that the US  physicist Conrad Longmire would propose   a theory for electromagnetic pulses from  high-altitude nuclear blasts that is still   the widely accepted explanation for why they are  orders of magnitude stronger than those generated   from blasts on the ground. Since then, our fears  of nuclear war not only included the scenario of   a warhead hitting a populated area, destroying  cities and creating nuclear fallout, but also   the possibility of one detonating far above our  heads in the upper atmosphere, sending a strong   enough EMP to disrupt electronic devices and even  take out the power grid. As with most weapons,   the best and most comprehensive research on  EMPs is classified. But, in 2019, a coalition   of energy organizations and government entities  called the Electric Power Research Institute (or   EPRI) funded a study to try and understand exactly  what could happen to the power grid from a high   altitude nuclear EMP. It’s not the only study  of its kind, and it’s not without criticism from   those who think it leans optimistic, but it has  the most juicy engineering details from all the   research I could find. And the answers are quite  a bit different than Hollywood would have you   believe. This is a summary of that report, and  it’s the first in a deep dive series of videos   about large-scale threats to the grid. I’m  Grady, and this is Practical Engineering. In   today’s episode, we’re talking about the impact  of a nuclear EMP on our power infrastructure. This video is sponsored by CuriosityStream  and Nebula. More on them later. A nuclear detonation is unwelcome in  nearly every circumstance. These events   are inherently dangerous and the physics of  a blast go way beyond our intuitions. That’s   especially true in the upper atmosphere where  the detonation interacts with earth’s magnetic   field and its atmosphere in some very unique  ways to create an electromagnetic pulse. An   EMP actually has three distinct components  all formed by different physical mechanisms   that can have significantly different impacts  here on Earth’s surface. The first part of an   EMP is called E1. This is the extremely fast and  intense pulse that immediately follows detonation. The gamma rays released during any nuclear  detonation collide with electrons, ionizing   atoms and creating a burst of electromagnetic  radiation. That’s generally bad on its own,   but when detonated high in the atmosphere,  earth’s magnetic field interacts with those   free electrons to produce a significantly stronger  electromagnetic pulse than if detonated within the   denser air at lower altitudes. The E1 pulse  comes and goes within a few nanoseconds,   and the energy is somewhat jokingly  referred to as DC to daylight,   meaning it’s spread across a huge  part of the electromagnetic spectrum. The E1 pulse generally reaches anywhere  within a line of sight of the detonation,   and for a high-altitude burst, this can  cover an enormous area of land. At the   height of the Yucca test, that’s a circle  with an area larger than Texas. A weapon   at 200 kilometers in altitude could impact a  significant fraction of North America. But,   not everywhere within that circle experiences  the strongest fields. In general, the further   from the blast you are, the lower the amplitude of  the EMP. But, because of earth’s magnetic field,   the maximum amplitude occurs a little bit south  of ground zero (in the northern hemisphere),   creating this pattern called a smile diagram.  But no one will be smiling to find out that   they are within the affected area  of a high altitude nuclear blast. Although a weapon like this wouldn’t  damage buildings, create nuclear fallout,   be felt by humans, or probably even be visible  to most, that E1 pulse can have a huge effect   on electronic devices. You’re probably familiar  with antennas that convert radio signals into   voltage and current within a conductor. Well, for  a strong enough pulse spread across a huge range   of frequencies, essentially any metallic object  will act like an antenna, converting the pulse   into massive voltage spikes that can overwhelm  digital devices. And, the E1 pulse happens   so quickly that even devices meant to protect  against surges may not be effective. Of course,   with just about everything having embedded  electronics these days, this has far reaching   implications. But on the grid, there are really  only a few places where an E1 pulse is a major   concern. The first is with the control systems  within power plants themselves. The second is   communications systems used to monitor and record  data to assist grid operators. The EPRI report   focused primarily on the third hazard associated  with an E1 pulse: digital protective relays. Most folks have seen the breakers that protect  circuits in your house. The electrical grid has   similar equipment used to protect transmission  lines and transformers in the event of a short   circuit or fault. But, unlike the breakers in your  house that do both the sensing for trouble and   the circuit breaking all in one device, those  roles are separate on the grid. The physical   disconnecting of a circuit under load is done  by large, motor controlled contactors quenched   in oil or dielectric gas to prevent the formation  of arcs. And the devices that monitor voltage and   current for problems and tell the breakers when to  fire are called relays. They’re normally located   in a small building in a substation to protect  them from weather. That’s because most relays   these days are digital equipment full of circuit  boards, screens, and microelectronics. And all   those components are particularly susceptible  to electromagnetic interference. In fact,   most countries have strict regulations about  the strength and frequency of electromagnetic   radiation you can foist upon the airwaves, rules  that I hope I’m not breaking with this device. This is a pulse generator I bought off eBay  just to demonstrate the weird effects that   electromagnetic radiation can have on  electronics. It just outputs a 50 MHz   wave through this antenna, and you can see  when I turn it on near this cheap multimeter,   it has some strange effects. The  reading on the display gets erratic,   and sometimes I can get the backlight to turn  on. You can also see the two different types   of E1 vulnerabilities here. An EMP can couple to  the wires that serve as inputs to the device. And   an EMP can radiate the equipment directly.  In both cases, this little device wasn’t   strong enough to cause permanent damage to the  electronics, but hopefully it helps you imagine   what’s possible when high strength fields  are applied to sensitive electronic devices. The EPRI report actually subjected digital  relays to strong EMPs to see what the effects   would be. They used a Marx generator  which is a voltage multiplying circuit,   so I decided to try it myself. A Marx generator  stores electricity in these capacitors as they   charge in parallel. When triggered, the spark  gaps connect all the capacitors in series to   generate very high voltages, upwards of 80 or 90  kilovolts in my case. My fellow YouTube engineer   Electroboom has built one of these on his  channel if you want to learn more about them. Mine generates a high voltage spark  when triggered by this screwdriver. Don’t try this at home, by the way. I didn’t design an antenna to convert  this high voltage pulse into an EMP,   but I did try a direct injection test. This cheap  digital picture frame didn’t stand a chance.   Just to clarify, this is in no way  a scientific test. It’s just a fun   demonstration to give you an idea of  what an E1 pulse might be capable of. The E2 pulse is slower than E1 because  it’s generated in a totally different way,   this time from the interaction of gamma rays  and neutrons. It turns out that an E2 pulse is   roughly comparable to a lightning strike.  In fact, many lightning strikes are more   powerful than those that could be generated by  high-altitude nuclear detonations. Of course,   the grid’s not entirely immune to lightning,  but we do use lots of lightning protection   technology. Most equipment on the grid is  already hardened against some high voltage   pulses such that lightning strikes  don’t usually create much damage. So,   the E2 pulse isn’t as threatening to our power  infrastructure, especially compared to E1 and E3. The final component of an EMP, called E3,  is, again, much different from the other two.   It’s really not even a pulse at all, because  it’s generated in an entirely different way.   When a nuclear detonation happens in the upper  atmosphere, earth’s magnetic field is disturbed   and distorted. As the blast dissipates, the  magnetic field slowly returns to its original   state over the course of a few minutes. This is  similar to what happens when a geomagnetic storm   on the sun disrupts earth’s gravity, and large  solar events could potentially be a bigger threat   than a nuclear EMP to the grid. In both cases,  it’s because of the disturbance and movement of   earth’s magnetic field. You probably know what  happens when you move a magnetic field through   a conductor: you generate a current. We call that  coupling, and it’s essentially how antennas work.   And in fact, antennas work best when their size  matches the size of the electromagnetic waves. For example, AM radio uses frequencies  between down to 540 kilohertz. That   corresponds to wavelengths that can  be upwards of 1800 feet or 550 meters,   big waves. Rather than serving as a place to  mount antennas like FM radio or cell towers,   AM radio towers are the antenna. The entire metal  structure is energized! You can often tell an AM   tower by looking at the bottom because  they sit atop a small ceramic insulator   that electrically separates them from the ground.  As you can imagine, the longer the wavelength, the   larger an antenna has to be to couple well with  the electromagnetic radiation. And hopefully you   see what I’m getting at. Electrical transmission  and distribution lines often run for miles, making   them the ideal place for an E3 pulse to couple  and generate current. Here’s why that’s a problem. All along the grid we use transformers to change  the voltage of electricity. On the transmission   side, we increase the voltage to reduce losses  in the lines. And on the distribution side,   we lower the voltage back down to make it  safer for customers to use in their houses   and buildings. Those transformers work  using electromagnetic fields. One coil   of wire generates a magnetic field that  passes through a core to induce current   to flow through an adjacent coil. In fact, the  main reason we use alternating current on the   grid is because it allows us to use these  really simple devices to step voltage up or   relationship between how much current flows and  the strength of the resulting magnetic field. But,   this relationship breaks down at the saturation  point, beyond which additional current won’t   create much further magnetism to drive  current on the secondary winding. An E3 pulse   can induce a roughly DC flow of current through  transmission lines. So you have DC on top of AC,   which creates a bias in the sine wave. If there’s  too much DC current, the transformer core might   saturate when current moves in one direction but  not the other, distorting the output waveform.   That can lead to hot spots in the transformer  core, damage to devices connected to the grid   that expect a nice sinusoidal voltage  pattern, and lots of other funky stuff. So what are the implications of all this? For the  E1 pulse damaging some relays, that’s probably not   a big deal. There are often redundant paths for  current to flow in the transmission system. That’s   why it’s called the grid. But the more equipment  that goes offline and the greater the stress on   the remaining lines, the greater the likelihood  of a cascading failure or total collapse. EPRI did   tests simulating a one megaton bomb detonated  at 200 kilometers in altitude. They estimated   that about 5% of transmission lines could have  a relay that gets damaged or disrupted by the   resulting EMP. That alone probably isn’t enough  to cause a large-scale blackout of the power grid,   but don’t forget about E3. EPRI found that the  third part of an EMP could lead to regional   blackouts encompassing multiple states because  of transformer core saturation and imbalances   between supply and demand of electricity.  Their modeling didn’t lead to widespread   damage to the actual transformers, and that’s a  good thing because power transformers are large,   expensive devices that are hard to replace,  and most utilities don’t keep many spares   sitting around. All that being said,  their report isn’t without criticism and   many believe that an EMP could result in far  more damage to electric power infrastructure. When you combine the effects of the E1 pulse and  the E3 pulse, it’s not hard to imagine how the   grid could be seriously disabled. It’s also easy  to see how, even if the real damages to equipment   aren’t that significant, the widespread nature  of an EMP, plus its potential impacts on other   systems like computers and telecommunications,  has the potential to frustrate the process of   getting things back online. A multi-day,  multi-week, or even multi-month blackout   isn’t out of the question in the worst-case  scenario. It’s probably not going cause a   hollywood-style return to the stone age for  humanity, but it is certainly capable of   causing a major disruption to our daily lives.  We’ll explore what that means in a future video. But if you have trouble waiting for  the next Practical Engineering video,   you should know that they go live on Nebula  before hitting YouTube, and you can watch them   without any ads. If you haven’t heard about  Nebula by now, it’s a streaming service built   by creators that uses a different model than  YouTube. Instead of being supported by ads,   you just pay a small subscription fee. That sounds  like a small difference, but the result is a   huge distinction in content, including videos  that just don’t work well on YouTube and lots   of original series from your favorite creators  like Wendover Productions and Real Engineering. And, we’re super excited to continue our  partnership with CuriosityStream, a service with   thousands of big-budget documentaries on pretty  much every subject you can imagine. Curiosity   Stream loves independent creators, so they’re  offering free access to Nebula when you sign   up at CuriosityStream.com/practicalengineering.  I know it’s a little hard to keep track of all   the streaming services out there right now, but  this bundle is so cheap that you barely have to   even consider it. You pay one time, 15 bucks, to  get an entire year of access to CuriosityStream   PLUS you get a free year of access to Nebula too.  If you’re looking for more about the power grid,   the How Cities Work series on CuriosityStream has  a whole 50 minute episode dedicated to just that.   Or, catch Sam from Wendover Productions traveling  around the world in his hit gameshow series,   Jet Lag, on Nebula. It’s a great way to  support my channel and a whole host of   your other favorite educational creators. Plus  it’s just a good deal. Do us both a favor and   click that link in the description. Thank you  for watching, and let me know what you think!

Channel: Practical Engineering

Views: 2,323,680

Keywords:

Id: FksEGpBLfis

Length: 17min 15sec (1035 seconds)

Published: Tue Nov 08 2022

Reddit Comments

[u/MasterArCtiK]

I love this channel, found it about a year ago and watch every one when they release. Always super educational and interesting topics

[u/hsfhsja]

Love the googly eyes on the oscilloscope

[u/Africa_versus_NASA]

The real danger (which he somewhat alluded to) is not so much from a nuclear weapon, but instead from naturally occurring geomagnetic storms originating from solar flares, like the Carrington Event:

https://en.wikipedia.org/wiki/Carrington_Event

That event occurred in 1859 and was so intense it made telegraph stations catch on fire. You can somewhat imagine what it would do in our modern age of highly sensitive digital technology. The good news is, we can kind of see this coming by monitoring the sun and space weather, and might be able to disconnect some of the more sensitive portions of the power grid ahead of time. The bad news is, it is difficult to EMP-harden the power transmission lines; about the most effective thing would be bury all of them, but that would be extremely expensive, time consuming, and in many places impossible.

[u/holman]

If you want a (rather terrifying) read on how this might impact civilization, I recommend reading One Second After:

https://en.m.wikipedia.org/wiki/One_Second_After

[u/FOTBWN]

Countries that have strategic nuclear weapons include this ability with strikes. A weapon is detonated in the atmosphere to create the EMP to knock out electronics which include communications and defence systems (good reason why military hardware is generally EMP hardened) shortly afterward the actual strikes happen.

If there's a time when a nuclear exchange could happen at any time and you're driving to work but suddenly everyone's car stops along with everything electronic for a seemingly unknown reason. You may as well step out of the car, put the sunglasses on and make peace with your maker.

[u/Nemo_Shadows]

Well I have to give this 2 thumbs up, pretty complete and accurate.

N. S

[u/The_Real_Dundarious]

DNA EM-1 - Capabilities of Nuclear Weapons is a good read (though heavily redacted).

"Detonations above about 130,000 feet produce EMP effects on the ground over areas that may encompass thousands of square miles. Although the strengths of these fields are less than half those in the highly ionized region surrounding a surface burst, they are of sufficient magnitude to damage electrical and electronic equipment. The mechanisms of formation of EMP are treated in Chapter 7. "