Mountain High-level Nuclear Waste Repository Research Articles

Bill to restart Yucca Mountain repository moves in Congress

Legislation to push forward the long-delayed Yucca Mountain high-level nuclear waste repository in Nevada cleared the U.S. House of Representatives Energy & Commerce Committee on June 28. The bill (H.R. 3053) would restart the permitting process, which has been mired in politics and technical issues and was killed by the Obama Administration eight years ago. The measure would allow siting of interim waste storage—in a location not yet selected—if progress on the geologic repository is demonstrated and a final decision on its licensing is “imminent.” As approved by the committee 49-4, the bill would also prohibit seabed disposal and exempt Great Lakes states from nuclear waste storage. In addition, the measure would increase Yucca Mountain’s planned capacity from 70,000 to 110,000 metric tons of waste. Nevada’s congressional delegation opposes the bill. Members of the Energy & Commerce Committee, which includes no Nevada representatives, predict a more protracted debate as the

The Secret of Yucca Mountain: Reflections on an Object in Extremis

The processes through which boundaries are made and unmade—conceptually, socially, and materially—have been of enduring interest to a wide range of social scientific disciplines including sociology, anthropology, geography, science studies, etc. The subject matter of this paper—the Yucca Mountain high-level nuclear waste repository in Nye county, Nevada, which is meant to keep such waste safe for 10 000 years—constitutes, we contend, a case study of such processes taken to extremes. This, in turn, makes Yucca Mountain an interesting vantage point from which to (re)view the traditional ontological and epistemological preoccupations characteristic of social science, not so much in terms of abstract theory but rather in terms of concrete practical problems of spatial and temporal organisation.

Porosity dependence of the elastic modulus of lithophysae-rich tuff: numerical and experimental investigations

Abstract The influence of porosity on the mechanical properties of rock has received much research attention. Portions of the Yucca Mountain high-level nuclear waste repository may be placed in tuff units containing lithophysal cavities, which are large, generally noninterconnected cavities that can be considered a form of macroscopic porosity. This paper presents the results of numerical modeling and uniaxial compression testing of analog models and tuff rock, in order to assess the relationships between elastic modulus and porosity. The first part of the paper presents numerical simulation of uniaxial compression testing to calculate the elastic modulus of two-dimensional models containing randomly distributed circular holes in plane strain. The range of porosities investigated is approximately 5–40%. In the second part, the elastic modulus determined from the uniaxial compression testing of analog models and tuff specimens is presented. The analog specimens were made of plaster of Paris containing varying amounts of spherical shaped Styrofoam® inclusions to simulate a cavity structure similar to tuff. The results from the numerical analysis and analog material testing show an exponential decrease in elastic modulus with increasing porosity, whereas the elastic moduli of tuff show a linear decrease. The difference in the two behaviors can be attributed to the nonuniform cavity shapes in the tuff specimens.

Sensitivity in volcanic hazard assessment for the Yucc Mountain high-level nuclear waste repository site: the model and the dat : Chih-Hsiang Ho, Mathematical Geology, 27(2), 1995, pp 239–258

Sensitivity in volcanic hazard assessment for the Yucc Mountain high-level nuclear waste repository site: the model and the dat : Chih-Hsiang Ho, Mathematical Geology, 27(2), 1995, pp 239–258

Sensitivity in volcanic hazard assessment for the Yucca Mountain high-level nuclear waste repository site: The model and the data

Both advocates and critics disagree on the significance and interpretation of critical geological features which relate to the safety and suitability of Yucca Mountain as a site for the construction of a high-level radioactive waste repository. Recent volcanism in the vicinity of Yucca Mountain is recognized readily by geologists and others with a knowledge of nuclear regulatory requirements as an important factor in determining future public and environmental safety. We regard basaltic volcanism as direct and unequivocal evidence of deep-seated geologic instability. Direct disruption of a repository site by basaltic volcanism therefore is a possibility. In this paper, sensitivity analysis of volcanic hazard assessment for the Yucca Mountain site is performed, taking into account some significant geological factors raised by experts. Three types of models are considered in the sensitivity data analysis. The first model assumes that both past and future volcanic activities follow a Homogeneous Poisson Process (HPP). The second model uses a Weibull Process (WP) to estimate the instantaneous recurrence rate based on the historical data at NTS (the Nevada Test Site). The model then switches from a WP of past events to a predictive HPP. The third model assumes that the prior historical trend based on a WP would continue for future activities. Hazards (at least one disruptive event during the next 10,000 years) using both classical and Bayesian approaches are evaluated based on the data for the following two observation periods: Pliocene and younger, and Quaternary. Combinations of various counts of events at volcanic centers of controversy and inclusion (or exclusion) of the youngest date at Lathrop Wells Center (=0.01 Ma) generate 90 different data sets. Sensitivity analysis is performed for each data set and the minimum and the maximum hazards for each model are summarized. We conclude that the estimated overall probability of at least one disruption of a repository at the Yucca Mountain site by basaltic volcanism during the next 10,000 years is bounded between 2.02×105 and 6.57×10−3.

Risk assessment for the Yucca Mountain high-level nuclear waste repository site: Estimation of volcanic disruption

In this article, we model the volcanism near the proposed nuclear waste repository at Yucca Mountain, Nevada, U.S.A. by estimating the instantaneous recurrence rate using a nonhomogeneous Poisson process with Weibull intensity and by using a homogeneous Poisson process to predict future eruptions. We then quantify the probability that any single eruption is disruptive in terms of a (prior) probability distribution, since not every eruption would result in disruption of the repository. Bayesian analysis is performed to evaluate the volcanic risk. Based on the Quaternary data, a 90% confidence interval for the instantaneous recurrence rate near the Yucca Mountain site is (1.85×10−6/yr, 1.26×10−5/yr). Also, using-these confidence bounds, the corresponding 90% confidence interval for the risk (probability of at least one disruptive eruption) for an isolation time of 104 years is (1.0×10−3, 6.7×10−3), if it is assumed that the intensity remains constant during the projected time frame.