Editing Yucca Mountain nuclear waste repository (section)

== Geology ==
{{Main|Yucca Mountain}}
[[File:YuccaMountain6-7-2005.JPG|thumb|upright=1.4|Looking west atop [[Yucca Mountain]]]]

The formation that makes up Yucca Mountain was created by several large eruptions from a [[caldera]] [[volcano]] and is composed of alternating layers of [[ignimbrite]] (welded tuff), non-welded tuff, and semi-welded tuff. The tuff surrounding the burial sites is expected to protect human health as it provides a natural barrier to the radiation.<ref>{{cite web |url=http://www.enviroliteracy.org/article.php/1349.html |title=Yucca Mountain |date=April 8, 2008 |publisher=The Environmental Literacy Council |access-date=2010-06-09 |quote=''Scientists believe that tuff has special chemical, physical, and thermal characteristics that make it extremely suitable for burying radioactive waste. As long as the waste stays solid and remains deep underground, it should not pose a threat to the environment or to human health as the layers of tuff shield the radiation.''}}</ref> It lies along the transition between the [[Mojave Desert|Mojave]] and the [[Great Basin Desert]]s.<ref>{{cite book |title=Ground water at Yucca Mountain: how high can it rise? |year=1992 |publisher=National Academy Press |location=Washington, D.C. |isbn=0-309-07669-2 |page=191}}</ref>

The volcanic [[tuff]] at Yucca Mountain is appreciably fractured and movement of water through an aquifer below the waste repository is primarily through fractures.<ref>U.S. Department of Energy. 2002. ''Yucca Mountain science and engineering report, revision 1''. Washington, DC: U.S. Department of Energy, Office of Civilian Radioactive Waste Management. {{cite web|url=http://www.ocrwm.doe.gov/documents/ser_b/index.htm |title=Yucca Mountain Science and Engineering Report Technical Information Supporting Site Recommendation Consideration Revision 1 |access-date=2011-03-24 |url-status=dead |archive-url=https://web.archive.org/web/20090515005004/http://www.ocrwm.doe.gov/documents/ser_b/index.htm |archive-date=May 15, 2009}}</ref> While the fractures are usually confined to individual layers of tuff, the faults extend from the planned storage area all the way to the water table {{convert|600|to|1500|ft|abbr=on}} below the surface.<ref>{{cite web |url=http://www.cyberwest.com/cw14/14scwst2.html |title=Earthquake could cause flooding of Yucca Mountain repository |date=September 2, 1997 |work= Cyberwest Magazine |access-date=2010-06-02}}</ref> Future water transport from the surface to waste containers is likely to be dominated by fractures. There is evidence that surface water has been transported down through the {{convert|700|ft|abbr=on}} of overburden to the exploratory tunnel at Yucca Mountain in less than 50 years.<ref>Vandenbosch, Robert, and Susanne E. Vandenbosch. 2007. ''Nuclear waste stalemate''. Salt Lake City, Utah: University of Utah Press, 12, pp. 106–107.</ref><ref>Norris, A. E., H. W. Bentley, S. Cheng, P. W. Kubik, P. Sharma, and H. E. Gove. 1990. "<sup>36</sup>Cl studies of water movements deep within unsaturated tuffs," ''Nuclear Instruments and Methods in Physics Research Section B'' 52 (December 2, 1990): 455–460.</ref>

The aquifer of Yucca Mountain drains to [[Amargosa Valley]], home to over 1400 people and a number of endangered species.<ref name=usa />

Some site opponents assert that, after the predicted containment failure of the waste containers, these cracks may provide a route for movement of radioactive waste that dissolves in the water flowing downward from the desert surface.<ref name=Summary>{{cite web |url=http://www.state.nv.us/nucwaste/yucca/ymsum01.htm |title=Summary of Yucca Mountain Oversight and Impact Assessment Findings |access-date=2008-05-16 |publisher=State of Nevada |year=1997}}</ref> Officials state that the waste containers will be stored in such a way as to minimize or even nearly eliminate this possibility.

The area around Yucca Mountain received much more rain in the geologic past and the water table was consequently much higher than it is today, though well below the level of the repository.

===Earthquakes===
The DOE has stated that seismic and [[tectonics|tectonic]] effects on the natural systems at Yucca Mountain will not significantly affect [[Seismic performance|repository performance]]. Yucca Mountain lies in a region of ongoing tectonic deformation, but the deformation rates are too slow to significantly affect the mountain during the 10,000-year regulatory compliance period. Rises in the water table caused by seismic activity would be, at most, a few tens of meters and would not reach the repository. The fractured and faulted volcanic tuff that Yucca Mountain comprises reflects the occurrence of many earthquake-faulting and strong ground motion events during the last several million years, and the hydrological characteristics of the rock would not be changed significantly by seismic events that may occur in the next 10,000 years. The engineered barrier system components will reportedly provide [[Earthquake engineering|substantial protection]] of the waste from seepage water, even under severe [[seismic loading]].<ref>{{cite web |url=http://ocrwm.doe.gov/documents/43222_tbd/index.htm |archive-url=https://web.archive.org/web/20080126070554/http://ocrwm.doe.gov/documents/43222_tbd/index.htm |archive-date=January 26, 2008 |title=Technical Basis Document No. 14: Low Probability Seismic Events |publisher=[[U.S. Department of Energy]]|work=[[Office of Civilian Radioactive Waste Management]] |date=June 2004 |access-date=2010-03-27}}</ref>

In September 2007, it was discovered that the Bow Ridge fault line ran underneath the facility, hundreds of feet east of where it was originally thought to be located, beneath a storage pad where spent radioactive fuel canisters would be cooled before being sealed in a maze of tunnels. The discovery required several structures to be moved several hundred feet further to the east, and drew criticism from Robert R. Loux, then head of the [[Nevada Agency for Nuclear Projects]], who argues that Yucca administrators should have known about the fault line's location years prior, and called the movement of the structures "just-in-time engineering."<ref>{{cite news |date=September 25, 2007 |title=Yucca Mt. adjusts to fault line |url=https://www.latimes.com/archives/la-xpm-2007-sep-25-na-yucca25-story.html |access-date=2010-03-27 |work=Los Angeles Times |location=Los Angeles, California}}</ref><ref>{{cite news |author=Attewill |first=Fred |date=September 25, 2007 |title=US nuclear dump plan in danger after seismic shock |url=https://www.theguardian.com/world/2007/sep/25/usa |access-date=2010-03-27 |work=The Guardian |location=London, England}}</ref>

In June 2008, a major nuclear equipment supplier, [[Holtec International]], criticized the DOE's safety plan for handling containers of radioactive waste before they are buried at the proposed Yucca Mountain Project. The concern is that, in an earthquake, the unanchored casks of nuclear waste material awaiting burial at Yucca Mountain could be sent into a "chaotic melee of bouncing and rolling [[juggernaut]]s".<ref>{{cite news |url=https://www.latimes.com/news/nationworld/nation/la-na-yucca6-2008jun06,0,5309730.story |title=Yucca Mountain safety plan is 'doomed,' nuclear company says |work=Los Angeles Times |date=June 6, 2008 |access-date=2010-03-27 |first=Ralph |last=Vartabedian}}</ref>