A thunderous pop.
What it sounds like inside a nuclear power plants cooling tower. Matt Ballos and Kevin Peterson of WSDG were out in Elma, Washington this week to visit NWAA acoustic test labs. The lab is built in a nuclear power plant that was abandoned a few weeks before it received its first uranium. In between the acoustic lab parts of the trip they were able to go around and explore the rest of the abandoned facility. This video is in one of the cooling towers. Even though it has an open top it does have a convex curve on the inside bottom of the tower. This shape makes for some awesome acoustics as you hear in the video.
The story of Elma's never-onlined nuclear plant:
Satsop Abandoned Nuclear Plant
The Satsop Nuclear Power Plant was 75% complete in 1983 before the money ran out and work was abandoned. To avoid steep dismantling costs, the site was eventually handed over to a public corporation and became the Satsop Development Park, home to various light industry businesses who work in the shadows of the two cooling towers. You can enter the property freely but you can't go under the towers (they're fenced off, although supposedly they are planning to open them to the public someday). Still, you can peek inside them since their bases are not solid (the hollow structures are held aloft by a zigzag of beams.) The tower at the site entrance was completely empty inside save for a lone port-a-potty
Obviously it's not too hard to gain entrance to at least one of the towers.