4 @ Containment of Underground Nuclear Explosions Containment Failures: Containment failures are unintentional releases of radioactive material to the atmosphere dueto failure ofthe containment system. They are termed *‘ventings,’’ if they are prompt, massive releases; or ‘‘seeps,”’ if they are slow, small releases that occur soon afterthe 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 purging is 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 samplesare 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. Since 1970, 126 tests have resulted in radioactive material reaching the atmosphere with a total release of about 54,000 Curies (Ci). Ofthis 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 Ci) as the main source. The lowerportion 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 Table 1-1—Releases From Underground Tests (normalized to 12 hours after event") Ail releases 1971-1988: Containment Failures: Camphor, 19719 ..00......00.... eee eee 360 Ci Diagonal Line, 1971 ................0..... 008, 6,800 Riola, 1980 2... 6. 3,100 Agrini, 1964 6. eee 690 Late-time Seeps: Kappeli, 1984......0 00.0 e eee 12 Tierra, 1984 0. eee eee 600 Labquark, 1986 ........ 2... eee 20 Bodie, 19867... ee eee $2 Controiled Tunnel Purgings: Hydla Fair, 1974 200 eee 500 Hybla Gold, 1977 0. cece ee ees 0.005 Miners tron, 1980 .. 11.0.0... 0.02. 0.3 Huron Landing, 1982 .............0. 0... ae 280 Mini Jade, 1983 20... ke nee Mill Yard, 1986 20... eens 5. 9 Diamond Beech,1985 ..............0.. 0... eee 1.4 Misty Rain, 1985 ........0..0.00. 000. 63 Mighty Oak, 1986.............0........0000. 36,000 Mission Ghost, 1987° .............0.0 00.000. 22 eee 3 Operational Releases: 108 tests from 1970-1988? ...... 5,500 Total since Baneberry: 54,000 Ci Major pre-1971 releases: Platte, 1962 ..... 00. eee 1,900,000 Ci Eel, 1962.0... ee eee 1,900,000 Des Moines, 1962 ................0..05. 11,000,000 Baneberry, 1970 ..................-2..00. 6,700,000 26 others from 1958-1970 ................. 3,800,000 Total: 25,300,000 Ci Other Releases for Reference NTS Atmospheric Testing 1951-1963: .. 12,000,000,000 Ci 1 Kitoton Aboveground Explosion:......... 10,000,000 Chernobyl (estimata):.... 6.066660. 81,000,000 8A+12 values apply only to containment failures, others are at time of release. OThe Camphorfailure includes 140 Ci from tunneipurging. “Bodie and Mission Ghostalso had drili-back releases. SManyof these operational releases are associated with tests that were not announced. SOURCE.Office of Technology Assessment, 1989. by pre-Baneberry undergroundtests (25,300,000 Ci), the early atmospheric tests at the Nevada Test Site (12,000,000,000 Ci), or even the amount that would be released by a single 1-kiloton explosion conducted aboveground (10,000,000 Ci). From the perspective of human health risk: If the same person hadbeen standing at the boundaryof the NevadaTest Site in the area of maximum concentration of radioactivity for every test since Baneberry (1970), that