Active Tectonics Impact on Society (1986) / Chapter Skim
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16. Volcanic Hazard Assessment for Disposal of High-Level Radioactive Waste
16. Volcanic Hazard Assessment for Disposal of High-Level Radioactive Waste
Pages 247-260
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From page 247... ...
Short-lived volcanic fields are more difficult to avoid but are generally mafic in composition, which results in smaller disruption zones and explosive eruptions of lower energy than those of long-lived centers. Volcanic hazards are evaluated through risk assessment, which is a product of probability and consequences.
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From page 248... ...
the use of risk-assessment techniques to evaluate volcanic hazards for the storage of high-level radioactive waste in luff in southern Nevada (Nevada Nuclear Waste Storage Investigations)
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From page 249... ...
The presence of shallow magma chambers, multiple feeder systems, and hydrothermal circulation systems above a magma chamber means that the potential effect of repository disruption by these magmas is much greater than that by magmas from monogenetic volcanic centers. The potential effect of eruption mechanisms on disruption and dispersal of the inventory of a waste repository is illustrated in Figure 16.1.
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From page 250... ...
These eruptions have greatly increased particle fragmentation and somewhat increased dispersal and fall within the Surtseyan field of Figure 16.1. In marked contrast, andesitic to silicic volcanic activity spans the sub-Plinian, Plinian, Vulcanian, and Ultraplinian fields of Figure 16.1.
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From page 251... ...
Volcanic Geology of the Nevada Test Site Region The NTS is located in southcentral Nevada approximately 80 km northwest of Las Vegas (Figure 16.2~. The current proposed site for burial of high-level radioactive wastes is Yucca Mountain, a linear range upheld by a thick accumulation of ash-flow and air-fall tuff and associated volcaniclastic rocks derived from the Timber Mountain-Oasis Valley caldera complex (Christiansen et al., 1977~.
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From page 252... ...
Type-II volcanic fields in the DV-PR volcanic zone include southernmost Death Valley, the NTS region, and Kawich Valley (Figure 16.2~.
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From page 253... ...
269~. PROBABILITY AND CONSEQUENCE ASSESSMENT Probability Several aspects of the history of basaltic volcanism in the NTS region provide justification for a probabilistic approach to volcanic hazards.
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From page 254... ...
(16.2~. The preferred definition of p is based on the distribution of volcanic centers in the DV-PR volcanic zone.
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From page 255... ...
The latter two calculations are strongly effected by the high cone density of the Lunar Crater volcanic field at the northern end of the DV-PR volcanic zone. The calculation of volcanic rates by using rates of magma production is based on Figure 16.5, an expanded version of Figure 16.3.
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From page 256... ...
This type of eruption occurred at three basalt centers in the NTS region during the past 10 m.y. The increased dispersal distance and the greater particle fragmentation of hydrovolcanic explosions, as noted previously, could greatly increase the consequences of repository disruption.
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From page 257... ...
A more extreme case, having major negative consequences for waste isolation, would be the possibility of exhumation of a buried repository during crater-forming hydrovolcanic explosions. This possibility is tested by data summarized in Figure 16.6, which is a relative-frequency diagram of crater depth for hydrovolcanic centers (maars and tuff 24~ Led ~ 3 / O MAX CRATER DEPTH-~ REPOS I TORY DEPTH .
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From page 258... ...
In particular, the site is located in a zone of active volcanism the Death Valley-Pancake Range volcanic zone and five Quaternary volcanic centers (1.2 to 0.3 m.y.) are present within a range of 8 to 20 km of the exploration block.
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From page 259... ...
. State of geological knowledge regarding potential transport of high-level radioactive waste from deep continental repositories, Environmental PTotection Agency Rep.
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From page 260... ...
Geology and petrology of the basalts of Crater Flat: Applications to volcanic risk assessment for the Nevada Nuclear Waste Storage Investigations, Los Alamos National Laboratory Rep.
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