The Chernobyl disaster, which took place on April 26, 1986, was a nuclear accident in Ukraine that occurred as a result of a reactor explosion and led to vast amounts of radioactive material being thrown into the environment. The impacts were severe, and it remains the worst nuclear disaster in history. Now, scientists suspect that solar storms powerful enough to collapse portions of modern power grids for months may hit the Earth more often than once in a century, reports The Guardian.

The warning comes after a power outage left millions of people in Spain, Portugal, and some parts of France without electricity on Monday, April 28. The chaos saw Spain's nuclear power plants automatically stopped, to which emergency generators stepped in. But the recent disruption of the power outages serves as an example of how risky power systems can be.

The USA is said to be particularly vulnerable. The majority of the commerical nuclear power power plants in the United States are located in east coast states and the upper midwest, two of the regions that are most at risk of solar storm blackouts.

During power outages, the nuclear reactors or emergency generators are not able to get power, yet the cooling pumps of the system still require to run even when the plant loses off-site power. Failures in the backup systems can lead to nuclear power plant accidents.

Additionally, in months-long blackouts, nuclear plants lose their supply of off-site electricity required for safe operation. Emergency diesel generators, a backup electricity source, are designed to power cooling pumps for days rather than months. No nuclear plant in the United States has ever lost offsite electricity for longer than a week.

The storage pools at nuclear plants that keep spent fuel assemblies, covering nuclear waste are also susceptible to accients as spent fuel assemblies can overheat and catch fire, leading to radioactive material being dispersed into the environment, if the storage pool's coolant water is lost.

In the US nuclear pools usually hold around six reactor core loads of nuclear fuel and are almost as packed with fuel assemblies as operarting reactors, which increases the odds of a critical failure.

Spent fuel fire in an exposed, densely packed storage pool could release 10 times as much caesium-137 as the Chernobyl accident is estimated to have released. This could result in thousands of square miles of land being contaminated and millions of people exposed to large amounts of ionizing radiation, many of whom might die from early or latent cancer.