Probabilistic Analysis of Human Intrusion in a High Level Nuclear Waste Repository in Salt Using Draft EPA Assumptions

1984 ◽  
Vol 44 ◽  
Author(s):  
William V. Harper ◽  
Gilbert E. Raines
Keyword(s):  
Nuclear Waste ◽  
Probabilistic Analysis ◽  
Discrete Event ◽  
Distribution Functions ◽  
Performance Assessments ◽  
Limiting Factors ◽  
Nuclear Waste Repository ◽  
Cumulative Probability ◽  
High Level Nuclear Waste ◽  
High Level

AbstractThe Office of Nuclear Waste Isolation (ONWI) has planned performance assessments that will quantify various performance measures for the eventual licensing of a repository in salt. In addition to studying “expected” conditions, selected discrete event scenarios must be analyzed. This paper presents a probabilistic analysis of a human intrusion scenario in which boreholes may be drilled into the repository, contact nuclear waste, and release the radionuclides to the environment. A stochastic analysis using draft EPA limiting factors regarding probability of drilling and quantities of water flow is compared to the proposed EPA 10,000 year limits. The years in which boreholes penetrate the repository are probabilistically determined in each iteration of the analysis. For each borehole, the probability of contacting radioactivity is an increasing function of time. When a borehole does make contact with radioactivity, the curie release of a given nuclide is a function of solubility limits and current inventory. Prediction intervals and complementary cumulative probability distribution functions are developed for the curie release as a fraction of the EPA limits. Radionuclide releases are small fractions of the EPA limits. This study shows that there is a high expectation that the EPA requirements would be met with a repository in salt.

Performance Assessments of Geologic Repositories for High-Level Nuclear Waste: Are They Necessary or Sufficient?

2004 ◽  
Vol 824 ◽  
Author(s):  
Rodney C. Ewing
Keyword(s):  
Performance Assessment ◽  
Nuclear Waste ◽  
System Analysis ◽  
Regulatory Compliance ◽  
Performance Assessments ◽  
Data Uncertainty ◽  
Emergent Properties ◽  
Total System ◽  
High Level Nuclear Waste ◽  
High Level

AbstractPerformance assessments of geologic repositories for high-level nuclear waste will be used to determine regulatory compliance. The determination, that with a “reasonable expectation” regulatory limits are met, is based on the presumption that all of the relevant physical, chemical and biological processes have been modeled with enough accuracy to insure that a confident judgment of safety may be made. For the geologic disposal of high-level nuclear waste, this generally means that models must be capable of calculating radiation exposures to a specified population at distances of tens of kilometers for periods of tens to hundreds of thousands of years. A total system performance assessment will consist of a series of cascading models that are meant in toto to capture repository performance. There are numerous sources of uncertainty in these models: scenario uncertainty, conceptual model uncertainty and data uncertainty. These uncertainties will propagate through the analysis, and the uncertainty in the total system analysis must necessarily increase with time. For the highly-coupled, non-linear systems that are characteristic of many of the physical and chemical processes, one may anticipate emergent properties that cannot, in fact, be predicted. For all of these reasons, a performance assessment is not in and of itself a sufficient basis for determining the safety of a repository, but it remains a necessary part of the effort to develop a substantive understanding of a repository site.

Comparison of Granite, Tuff, and Basalt as Geologic Media for Long-Term Storage of High-Level Nuclear Waste

1990 ◽  
Vol 212 ◽  
Author(s):  
D. E. Grandstaff ◽  
V. J. Grassi ◽  
A. C. Lee ◽  
G. C. Ulmer
Keyword(s):  
Nuclear Waste ◽  
Nuclear Waste Repository ◽  
Long Term Storage ◽  
Hydrothermal Experiments ◽  
Ion Activity ◽  
Activity Ratios ◽  
High Level Nuclear Waste ◽  
High Level ◽  
Term Storage

ABSTRACTSystematic differences in pH, cation/proton ion activity ratios, and redox have been observed between solutions produced in rock-water hydrothermal experiments with tuff, granite, and basalt. Stable pH values in tuff-water experiments may be as much as 1.5 pH units more acidic than basalt-water experiments at the same temperature and ionic strength. Redox (log fO2) values in 300°C tuff experiments are 4–7 orders of magnitude more oxidizing than basalt experiments and ca. 4 log units more oxidizing than the magnetite-hematite buffer. Such fluid differences could significantly affect the performance of a high-level nuclear waste repository and should be considered in repository design and siting.

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