Yucca mountains

Spent nuclear fuel has fission products, uranium, and transuranic elements. Plans call for permanent disposal in underground repositories. Geological studies are in progress at the Yucca Mountain site in Nevada. Until a repository is completed, spent fuel must be stored in water pools or in dry storage casks at nuclear plant sites. 

Tuff, a compressed volcanic material, is the primary constituent of Yucca Mountain, near Las Vegas, Nevada, the site selected by Congress in 1987 for assessment for spent fuel disposal. An underground laboratory, to consist of many kilometers of tunnels and test rooms, is to be cut into the mountain with special boring equipment to determine if the site is suitable for a repository. 

The primary issue is to prevent groundwater from becoming radioactively contaminated. Thus, the property of concern of the long-lived radioactive species is their solubility in water. The long-lived actinides such as plutonium are metallic and insoluble even if water were to penetrate into the repository. Certain fission-product isotopes such as iodine-129 and technicium-99 are soluble, however, and therefore represent the principal although very low level hazard. Studies of Yucca Mountain, Nevada, tentatively chosen as the site for the spent fuel and high level waste repository, are underway (44). 

A Proposed Public Health and Safety StandardforYucca Mountain, A Report prepared for the National Academy of Sciences Committee on Technical Bases for Yucca Mountain Standards, EPRI TV-104012, Electric Power Research Institute, Palo Alto, Calif., Dec. 1994. 

Yucca Mountain, if it becomes the site for the isolation of SNF, will be laced with tunnels, waste in storage casks and monitoring equipment. A waiting period is planned while better isolation alteniadvcs are sought. IfYucca Mountain is not used, it is to be refilled with the tuff material removed earlier. In the United States the SNF that would be isolated in Yucca Mountain would be waste that has not been reprocessed it would be material that has come out of nuclear reactors and has been cooled at the plant site. 

If one just concentrates on the radioactive material in SNF, the volume is very small, especially compared to waste from other power production practices. However, one can only discuss the separated radioactive material if it has undergone extensive reprocessing. If SNF is to be isolated, as in a place such as Yucca Mountain, with perhaps 70 miles of tunnels, the volume is that of the interior of this minor mountain. Isolation of up to 100,000 metric tons of SNF in Yucca Mountain means that for the United States, approximately all the SNF made to date and that expected in the operating lifetime of all current reactors can be put there. Approximately 2,000 metric tons of SNF are produced each year in the United States. Waste volume and placement depend on the amount of compaction and consolidation at the sites. The plans for the Yucca Mountain present a realistic and understandable picture of the volume of SNF. 

December. U.S. Congress approves Yucca Mountain, Nevada, as the only repositoiy site for high-level nuclear waste. 

Wolfsberg, K. Aguilar, R.D. Bayhurst, B.P. Daniels, W.R. DeVilliers, S.J. Erdal, B.R. Lawrence, F.O. Maestas, S. Mitchell, A.J. Oliver, P.Q. Raybold, N.A. Rundberg, R.S. Thompson, J.L. Vine, E.N. "Sorption-Desorption Studies on Tuff. III. A Continuation of Studies with Samples from Jackass Flats and Yucca Mountain, Nevada", Report LA-8747-MS, Los Alamos National Laboratory, 1981. 

Last December, Secretary Richardson submitted the Viability Assessment of a Repositoy at Yucca Mountain to Congress and the President. We are on track for a 2001 suitability decision on Yucca Mountain as the location of a repository, and, assuming suitability, to submit a license application to the NRC in 2002. 

It is important to underscore that the scientific and technical work being carried out at Yucca Mountain represents cutting edge science on a first-of-a-kind project The licensing process - for a project whose performance is to be projected over such long time scales - will also break new ground. 

Some utilities are providing long-term on-site dry cask storage others are negotiating with Native American nations for storage on reservations, while others propose shipment of spent fuel to Yucca Mountain for interim, retrievable storage. But these options do not address waste disposal and will not convince an informed public that the waste problem has been solved. 

Without confronting the complexity of studying and evaluating the TSPAs, one can gain some perspective on the scale of the hazards by considering the protective standards that have been proposed for nuclear waste repositories, in particular for the proposed US. site at Yucca Mountain (Bodansky, 1996). There have been three major proposals in recent years ... 

The specified limit is for a repository containing 100,000 tonnes of fuel. For Yucca Mountain, with an expected 70,000 tonnes, the limit would be proportionately lower. 

Overall, in focussing on such quantitatively minute and temporally remote harm, the NAS panel, the EPA, and the NRC are providing very suggestive, albeit indirect, evidence that the dangers from Yucca Mountain are small - certainly small compared to the open-ended dangers considered below. Indeed, it is hard to avoid the impression that the concern... 

For nuclear waste disposal, in a site such as Yucca Mountain, if the maximally exposed individual receives the proposed annual limit of 0.15 mSv, present estimates (based on the linearity hypothesis) suggest a 0.00 1 % risk of an eventual fatal cancer. The maximum dose is reached only if the wastes are dissolved in a small volume of water, and therefore only a limited number of people would receive this dose. If this number were as high as 1000, the implied toll for Yucca Mountain neighbors would be one cancer fatality per century per repository site.19 This toll would not start for many centuries, when the waste canisters begin to fail, and it not unreasonable to expect that cancer prevention and treatment will be much improved by then. Ignoring this prospect, and assuming many repositories and some doses above the prescribed limit, it still appears that the expected toll would be well under a thousand deaths per century. 

Progress in the establishment of a permanent waste repository, presumably at Yucca Mountain, within a framework of reasonable waste disposal standards. 

EPA, 1999, 40 CFR Part 197, Environmental Radiation Protection Standards for Yucca Mountain,... 

NAS/NRC 1995, Technical Bases for Yucca Mountain Standards, Committee on Technical Bases for Yucca Mountain Standards, National Research Council, Robert W. Fri, ch., National Academy Press, Washington, D.C. 

Zhang K., Wu Y.S., et al. Parallel commuting simulation of fluid flow in the unsaturated zone of Yucca Mountain, Nevada. 2003 Journal of Contaminant Hydrology.62-... 

More than 6 billion has been spent on high-level waste disposal. Spent fuel can be deadly for tens of thousands of years. In order to isolate it from the environment, nuclear waste is to be buried deep underground. Nevada s Yucca Mountain has been under consideration for decades and many in the nuclear industry believe that the Clinton administration blocked action on this site to gain support in this area. 

Yucca Mountain may be the most studied area in history. The federal government claims that the environmental effects of the repository will be small and have essentially no adverse impact on public health and safety. These claims have been challenged and there has not been the political will to go ahead with the site. 

Anghel I, Turin HJ, Reimus PW (2002) Lithium sorption to Yucca Mountain tuffs. Appl Geochem 17 819-824... 

Fig. 16.7 Plutonium L -edge XANES spectra plotted with respect to the relative XANES edge energy for sorbed Pu on Yucca Mountain tuff at 6 months and 2 years. All spectra taken after two years indicated an average oxidation state of Pu(IV) those taken after 6 months had average oxidation states predominantly of Pu(V) and Pu(VI). Reprinted with permission from Powell BA, Duff MC, Kaplan DI, Field RA, Newville M, Hunter BD, Bertsch PM, Coates JT, Serkiz SM, Sutton RS, Triay IR, Vaniman DT (2006) Plutonium oxidation and subsequent reduction by Mn(IV) minerals in Yucca Mountain tuff. Environ Sci Technol 40 3508-3514. Copyright 2006 American Chemical Society...

Underground chambers are also constructed in frozen earth (see subsection Low-Temperature and Cryogenic Storage ). Underground tunnel or tank storage is often the most practical way of storing hazardous or radioactive materials, such as proposed at Yucca Mountain, Nevada. A cover of 30 m (100 ft) of rock or dense earth can exert a pressure of about 690 kPa (100 Ibftin ). 

The goal may or may not be achieved. The state of Nevada and a number of environmental groups have been battling the Yucca Mountain plan since the day it was first announced in 1987. Some of the major concerns are that, in spite of all precautions, wastes may leak out of their containers and contaminate the water table ... 

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