• Madison420@lemmy.world
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      2 days ago

      Yes but very slightly.

      The Gnome detonation created a cavity about 170 ft (52 m) wide and almost 90 ft (27 m) high with a floor of melted rock and salt. A new shaft was drilled near the original and, on 17 May 1962, crews entered the Gnome Cavity. Even though almost six months had passed since the detonation, the temperature inside the cavity was still around 140 °F (60 °C). Inside, they found stalactites made of melted salt, as well as the walls of the cavity covered in salt.[9] The intense radiation of the detonation colored the salt multiple shades of blue, green, and violet.[2] Nonetheless, the explorers encountered only five milliroentgen, and it was considered safe for them to enter the cavern and cross its central rubble pile. While the three-kiloton explosion had melted 2400 tons of salt, the explosion had caused the collapse of the sides and top of the chamber, adding 28,000 tons of rubble that mixed with the molten salt and rapidly reduced its temperature. This was the reason the drilling program had originally been unsuccessful, finding temperatures of only 200 °F (93 °C), without high pressure steam, though the boreholes had encountered occasional pockets of molten salt at up to 1,450 °F (790 °C) deeper amid the rubble.[

    • SubArcticTundra@lemmy.mlOP
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      2 days ago

      It says in the wiki article that they usually did collapse, with this one being an exception thanks to it being made in rigid salt rock. The radioactivity dropped quite fast iirc, but the cavern did still have a temp of 60C when they drilled in to it 2 weeks later