If electric power were out 12 to 31 days (depending on how hot the stored fuel was), the fuel from the reactor core cooling down in a nearby nuclear spent fuel pool could catch on fire and cause millions of flee from thousands of square miles of contaminated land, because these pools aren’t in a containment vessel.
This could happen from the long power outage resulting from an electromagnetic pulse, which could take the electric grid down for a year ( see U.S. House hearing testimony of Dr. Pry at The EMP Commission estimates a nationwide blackout lasting one year could kill up to 9 of 10 Americans through starvation, disease, and societal collapse. At this hearing, Dr. Pry said “Seven days after the commencement of blackout, emergency generators at nuclear reactors would run out of fuel. The reactors and nuclear fuel rods in cooling ponds would meltdown and catch fire, as happened in the nuclear disaster at Fukushima, Japan. The 104 U.S. nuclear reactors, located mostly among the populous eastern half of the United States, could cover vast swaths of the nation with dangerous plumes of radioactivity” )
After the nuclear fuel that generates power at a nuclear reactor is done, it’s retired to a spent fuel pool full of water about 40 feet deep. Unlike the nuclear reactor, which is inside a pressure vessel inside a containment vessel, spent fuel pools are almost always outside the main containment vessel. If the water inside ever leaked or boiled away, it is likely the spent fuel inside would catch on fire and release a tremendous amount of radiation.
Nuclear engineers aren’t stupid. Originally these pools were designed to be temporary until the fuel had cooled down enough to be transported off-site for reprocessing or disposal. But now the average pool has 10 to 30 years of fuel stored at a much higher density than the pools were designed for, in buildings that vent to the atmosphere and can’t contain radiation if there’s an accident.
There are two articles from Science below (and my excerpts from the National Academy of Sciences these articles refer to in APPENDIX A)
If the electric grid power fails, backup diesel generators can provide power for 7 days without resupply of diesel fuel under typical nuclear plant emergency plans. If emergency diesel generators stop working, nuclear power plants are only required to have “alternate ac sources” available for a period of 2 to 16 hours. Once electric power is no longer supplied to circulation pumps, the spent fuel pool would begin to heat up and boil off. It would only take 4 to 22 days from when water was no longer cooling the fuel to ignite the zirconium cladding within 2 to 24 hours (depending on how much the fuel had decayed). Without more water being added to the spent fuel pool, the total time from grid outage to spontaneous zirconium ignition would likely be 12-31 days (NIRS).
The National Research Council estimated that if a spent nuclear fuel fire happened at the Peach Bottom nuclear power plant in Pennsylvania, nearly 3.5 million people would need to be evacuated and 12 thousand square miles of land would be contaminated. A Princeton University study that looked at the same scenario concluded it was more likely that 18 million people would need to evacuated and 39,000 square miles of land contaminated.
Besides a geomagnetic or nuclear EMP threat, there can also be a loss of offsite power from events initiated by severe weather (i.e. hurricanes, tornadoes, etc) that could cause a spent fuel pool to catch on fire. Other events include an internal fire, loss of pool cooling, loss of coolant inventory, an earthquake, drop of a cask, aircraft impact, or a missile.
Alice Friedemann www.energyskeptic.com author of “When Trucks Stop Running: Energy and the Future of Transportation, 2015, Springer]
Stone, R. May 24, 2016. Spent fuel fire on U.S. soil could dwarf impact of Fukushima. Science Magazine.
A fire from spent fuel stored at a U.S. nuclear power plant could have catastrophic consequences, according to new simulations of such an event.