Chapter 3—Containing Underground Nuclear Explosions @ 45 Figure 3-8—Tunnel Closure Sequence A ier ‘ ———- ime Working dont Mauttier | LES 9106 2ca closure TAPS, Ground | snock Mechanica ¢osure MAC Stemming olug 8 eS | | | Tesi cnamoer . g E1c of slemmin Mecnanical ciosureiGSAC) yy Qa » 003 seconds pommel presen eyo a » Mecnarica closure: TAPS) Working aoin* Bg = | Mecran ca! closuretGSACi 7 = LA Test chamber Ena of stemming Mecnarical ccsurei MAC) Ground \ spock . Stemming ofug \ C005 seconds \ f Warkin / Residual stress hed e Test chamber End of stemming / Mecnanical ciasure( MAC, Ze (Peak -0 3 kbar) \\ > \ Goa: snore Stemming dlug Final cavity 02 a Mecnanical c‘osuret TAPS) Mecranica: closuretGSAC | Point, ° BD = 3 (<0. kbar) 1 | Working point Mechanical closures TAPS} Mechanical closureiGSACy ‘ \ des = seconds | | Test chamoer : Eng of sterming » Mecnanical c osurerMAC) Residual stress field (Peak “0 3 kbar) . Final cavity —€ 975 0 1 koar) ! Stemming olug seconds ~ | Working point } 7 | Mecnamecal closureiTAPS: Mecranica ciosurerGSAC) Ead nd Test chamoer of y by of stemmin siemming Mechanica: ciosureiMAC: A) Zero Time: Explosion is detonated and the first two mechanical closures arefired. B) Within 0.03 seconds, a stemming piugis being formed and mechanical pipe closure has occurred. C) Within 0.05 seconds, the stemming plug has formed. D) Within 0.2 seconds,cavity growth is complete and a surrounding compressive residual stressfield has formed. E) Within 0.75 seconds, closure is complete. SOURCE. Modified from Defense Nuclear Agency.