Add this one to the natural disaster category. I’ve mentioned EMP, and stated it’s unlikely as a reason for the grid to go down but there’s actually a far more plausible scenario. If the sun spits out a giant flare, it can create a large EMP-like effect on long electrical conductors. There’s no fast rise time pulse that frappes solid state devices, but it generates similar magnitude low frequency currents. These can cause core saturation in the large HV utlity transformers, which causes them to overheat and self-destruct. This has actually happened in recent memory, and caused some major damage and outages even with the moderate levels of solar flux seen in those events.

I say moderate because there are truly massive flares that occur every 500 years or so, with lesser ones every 100. The biggest on record was the Carrington Event in 1859, this caused telegraph lines to fail and catch on fire. Another one occurred in 1921, with less magnitude but with many power system failures. Utilities are installing neutral resistors to stop the transformer failures, but in a large event the transmission lines may fail. And, having large sections of the grid down will tend to bring all the local generators down with it, since they are all interconnected. The system isn’t designed to operate in “island” mode, there’s a lot of load sharing and synchronization between all the elements. There have been cases of a single HV line going down, and taking large areas off line for days (even with no damage). It takes that long to get everything reconnected. If multiple areas are off or at partial capacity, it may take weeks or longer to get power back. Turning off power for weeks would be the worst thing to ever occur in this country, things would just grind to a stop. Think about the lack of food storage, working hospitals, fuel and water pumping, banking/finance, lighting, etc. It wouldn’t even have to be for that long, many people would be in trouble within hours. That would be bad enough, but it gets better…

It’s a little known fact that all nuclear power plants store depleted fuel rod assemblies on site. These assemblies are highly radioactive and give off lots of heat, so the utilities store them in concrete pools filled with water.  The water is needed for shielding, and most importantly to prevent the rods from getting so hot they melt and burn. The pools are packed well past capacity due to the cancelling of the Yucca storage facility, so a loss of water pumping would cause the water to boil off in a matter of days. In theory each plant has a way to add water via diesel pumps, but if this isn’t done you get a radiation leak from the meltdown in the pool. Interestingly, the storage pools are not covered with a concrete dome, they are usually metal roofed commercial buildings. So, a fire would cause the facility to vent radioactive smoke in a long plume downwind of the site.   Sort of like Chernobyl. Depending on all the variables like wind speed, direction, how much fuel was stored, how long the operator was able to add water, you could get a really horrible situation repeated N times across the country.

I can’t find out much about how likely this is, there’s very little information about how the NRC plans to add water in the event of a grid collapse. They seem to spend all their energy downplaying the likelihood of the grid shutting off, while not mentioning how to avoid it or the outcome.  So add Gieger counters, dosimeters, and sandbags to the planning list.  If you get stuck in an area downwind of a nuke site, things may be hot so it’s best to have some sort of shelter.  

I’m mostly pondering the grid outage, not so much the poly Cherynobyl. If you stop and think, it seems like something that could happen due to the lack of backups. But, maybe I’m overly pessimistic. As I’ve said, people are pretty resourceful but it could be a while to recover from that. It supports the idea of having a 2-4 week reserve, and some electric backup.