Project Operations
The Purpose of Performance Assessment

The Performance Assessment staff estimates how the Project's total repository system will work and meet regulations set by the Environmental Protection Agency that are also requirements of the Nuclear Regulatory Commission. Mathematical models help scientists and engineers fine-tune their research and designs to develop a repository system that protects people and the environment. These modeling studies define processes and events that affect the system, and calculate the amount and type of radioactive materials that could be released to the environment. These studies are called total system performance assessments.

Scientists repeat these assessments as new elements are introduced. Hydrologists, geochemists, earth scientists, materials scientists, and engineers all work together. This collaboration forms a built-in review in which experts comment on each other's work. To make sure a performance assessment is complete, all review comments are addressed and new results incorporated as necessary.

The Performance Assessment staff's challenge is to support achieving a system that impacts people and the environment as little as possible. For example, they evaluate risks posed by a repository to the area's groundwater. For their calculations, the scientists use a boundary of 20-30 kilometers, which marks the current location of the people living nearest to Yucca Mountain. They evaluate effects of radioactivity from the repository that reaches the water table. To date, calculations show that, for a 10,000-year period, there will be no dose to people that is likely to affect their health. As another example, the group studies how volcanoes and earthquakes might affect the site. In this instance, they found the chance of a volcano's erupting through the repository to be 1 chance in 70,000,000 per year over 10,000 years.

Safety is the biggest concern facing the Project. The Performance Assessment staff integrates knowledge from science and engineering. They also study the effects of uncertainties, such as natural events and human interference, on the repository. The group tests and confirms all decisions about the total repository system, explaining how it meets or fails to meet regulatory requirements. They must take a true scientific approach, documenting all results without bias.

 

Additional Information:
Why Yucca Mountain?	History of nuclear waste program
Who's watching us?	Project Fact Sheets
Project Operations	Transportation
Project Databases	Employment Opportunities

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