 They are installed at all facilities in the United States and United Kingdom which do warhead assembly and disassembly, the largest being the Pantex plant in Amarillo, Texas, which has 12 Gravel Gerties.Bunkers deflect the blast wave from nearby explosions to prevent ear and internal injuries to people sheltering in the bunker.While frame buildings collapse from as little as 3 psi (0.2 bar) of overpressure, bunkers are regularly constructed to survive several hundred psi (over 10 bar).