Chapter 3—Containing Underground Nuclear Explosions @ 45 Figure 3-8—Tunnel Closure Sequence A Zero RF - tume | | | Working oaint Muffler set | LOS pipe | Mecnanical closure: TAPS: / Mechanica! c:osuretGSAC, Grounc SPOCK end of stemming Mechanica! closure: MAC) Stemming 9149 B » 933 p= h Qe , ee | ee = seconds 1 Test cnamber / | Working oint S Mechanical zosuret TAPS. | Mechanicai 2 osuraiGSACi é “est ~amper Eng of stemming Mecrar cal cosurei MAC: ° Groung srock ® Stemming dtug \ \ c 905 seconds — Pp ' \ Workin Point ° — _—p_/ a t Mechancal c'osurei TAPS: Mecnan.cai closureiGSAC) | mal - ——— Test chamber ~ . End af stemming Mecnanical closureiMAC, Residual stress Fieig a ‘Peak -0 3 «bar: » \ D Stemming : Diug 02 seconas qT wt Mechanical closurer TAPS | Working ooint Mecnanical ciosure(GSAC) a + — . “ast chameer Ly Eng of stemiring Mechanical closure:MAC: » Residual stress field (Peak 0 3 kbar) Final cavity (<0 1 kbar) — \ 1 Stemming pig yl 975 seconds — | Y Working point J | Mecnanical Closure: TAPS) Mechanical ciosuretGSAC: r | Aa =i — f ; Test est chamoer cna Erg af stemming Mechanica! ciosureiMAC: A) Zero Time: Expiosion is detonated and thefirst two mechanical closuresare fired. B) Within 0.03 seconds, a stemming plug ‘s 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 stress field has formed. E) Within 0.75 seconds, closure is comclete SOURCE: Modified from Defense Nuclear Agency.