4 @ Containment: of Underground Nuclear Explosions Containment Failures: Containment failures are unintentional releases of radioactive material to the atmosphere dueto a failure of the containment system. They are termed ‘‘ventings,’’ if they are prompt, massive releases; or **seeps,”” if they are slow, small releases that occur soonafter the test. Late-Time Seeps: Late-time seeps are small releases that occur days or weeksafter a test when gases diffuse through pore spaces of the overlying rock and are drawn to the surface by decreases in atmospheric pressure. Controlled Tunnel Purging: A controlled tunnel purgingis an intentional release to allow either recovery of experimental data and equipmentor reuse of part of the tunnel system. Operational Release: Operational releases are small, consequential releases that occur when core or gas samples are collected, or when the drill-back hole is sealed. The containment record can be presented in different ways depending on which categories of releases are included. Reports of total numbers of releases are often incomplete because they include only announcedtests or releases due to containmentfailure. The upper portion of table 1-1 includes every instance (for both announced and unannouncedtests) where radio- active material has reached the atmosphere under any circumstances whatsoever since the 1970 Baneberry test. Table 1-1—Reieases From Underground Tests (normalized to 12 hours after event*) All releases 1971-1988: Containment Failures: Camphor, 19719 0. ccc cee 360 Ci Diagonal Line, 1971 .............. ccs 6,800 Riola, 1980 2.0... cece eee 3,100 Agrini, 1984 260. ce eee 690 Late-time Seeps: Kappeli, 1984 0. ec eee 12 Tierra, 1984 20. 600 Labquark, 1986 2000. eee 20 Bodie, 19867... eee 52 Controlled Tunne! Purgings: Hybla Fair, 1974..0.......0....0 0. eee 500 Hybla Gold, 1977... 00.0. 0.005 Miners lron, 1980 ..........0. 0.00.0. 0.3 Huron Landing, 1982 .................2.....-0. 280 Mini Jade, 1983.00.00... 0. cee 1 Mill Yard, 1985.0... 0... eee 5.9 Diamond Beech,1985 ................. 0.002000 0 1.1 Misty Rain, 1985 ............... 0... 63 Mighty Oak, 1986.......................0005. 36,000 Mission Ghost, 1987¢ ..................0000 000005 3 Operational Releases: 108 tests from 1970-19887 ..........000.0.00000.. 5,500 Total since Baneberry: 54,000 Ci Major pre-1971 releases: Platte, 1962............0...0..0..000000. . 1,900,000 Ci Eel, 1962... 0... cee 1,900,000 Des Moines, 1962 ...................... 11,000,000 Baneberry, 1970 ....................... 6,700,000 26 others from 1958-1970 ............... . 3,800,000 Other Releases for Reference Total: 25,300,000 Ci NTS Atmospheric Testing 1951-1963: .. 12,000.000.000 Ci 1 Kiloton Aboveground Explosion: ....... 10,000,000 Chernobyl (estimate):........0..0...0.000.0. 81,000,000 8A+12 values apply only to containment failures, others are at time of release. oThe Campnhorfailure includes 140 Ci from tunnel purging °Bodie and Mission Ghost also had dnili-back releases CMany of these operational releases are associated with tests that were not announced. SOURCE: Office of Technology Assessment, 1989 Since 1970, 126 tests have resulted in radioactive material reaching the atmosphere with a by pre-Baneberry undergroundtests (25,300,000 Ci), the early atmospheric tests at the Nevada amount, 11,500 Ci were due to containment failure and late-time seeps. The remaining 42,500 Ci were operational releases. and controlled tunnel purgings—with Mighty Oak (36,000 amount that would be released by a single 1-kiloton explosion conducted aboveground (10,000,000 Ci). total release of about 54,000 Curies (Ci). Ofthis Ci) as the main source. The lower portion of the table shows that the release of radioactive material from underground nuclear testing since Baneberry (54,000 Ci) is extremely small in comparison to the amount of material released Test Site (12,000,000,000 Ci), or even the From the perspective of humanhealth risk: If the same person hadbeenstanding at the boundary of the Nevada Test Site in the area of maximum concentration of radioactivity for every test since Baneberry (1970), that