U.S. Department of Energy

As the world teeters on the brink of a nuclear confrontation with North Korea, FEMA and the U.S. Department of Energy are preparing to wargame so-called "Black Sky Hazards" that could result in a "subcontinent scale, long duration power outage, with cascading failure of all our other increasingly interdependent infrastructures."  Here's how EarthEx2017 described the exercise:

Just ten days after the emergency at Washington's Hanford nuclear facility in early May, when a tunnel collapse prompted concerns about radioactive waste fallout as we described then in "'Serious Situation' After Tunnel Collapse At WA Nuclear Facility; Evacuation Ordered, No-Fly Zone In Place", we reported that the U.S. Department of Energy was scrambling to deal with a second emergency, when signs emerged that a massive underground double shell nuclear waste holding tank may also be leaking.