Project Operations
Engineered Barrier System

The Engineered Barrier System, or man-made parts of the repository, helps prevent the release of highly radioactive materials from Yucca Mountain for hundreds of thousands of years. This system is made up of containers holding the materials and tunnels deep underground.

The specially designed containers, or waste packages, rest on support stands inside the tunnels. The tunnels, lined with concrete, hold the stands, set on concrete platforms on a concrete floor. To protect the packages from moisture, options include drip shields and backfill. The Engineered Barrier System, combined with the natural system, comprises the total repository system that functions as multiple layers of protection preventing the movement of radioactive materials.

The professionals who do this work are metallurgists, heat-transfer specialists, computer modelers, hydrologists, geologists, planners, and engineers. The engineers are experts in branches of engineering such as mining, geotechnical, civil, chemical, mechanical, electrical, nuclear, and control.

To design the engineered barrier, the staff studies many pieces of information. For example, they decide how many years the Engineered Barrier System must last. The length of time then becomes a design requirement. Once this step has been completed, engineers create computer models to see how strong the barriers must be to keep highly radioactive materials from moving out of the tunnels. The data from these models is used to design the waste packages and the tunnels.

The team designing the waste packages studies the types of radioactive materials that will be disposed. These materials are in different forms and have different levels of radioactivity. As a result, the engineers study rare metals (such as titanium), corrosion-resistant steel, and concrete to gauge their ability to contain the radioactive materials. Using the information from all these studies and the computer models, the team designs packages to meet the design requirements. The data helps the designers decide how to build the tunnels to keep the packages intact.

Another team studies the elements that could affect the waste packages. One such element is the movement of water through the rock; another is the heat from the radioactive materials. Water can cause the waste packages to wear away (corrode) over time; on the other hand, heat from the materials vaporizes water that enters the tunnel. However, once the radioactive materials cool down, water becomes more of a concern. Protecting the packages from corrosion is very important. Designers consider many options to reduce water's effects. For example, they could backfill the tunnels, use drip shields, or both.

The Engineered Barrier System is essential to the Project's long-term goal of safely disposing of highly radioactive materials for hundreds of thousands of years. The experts planning for the different parts of the system not only cross-check one another's work, but also work closely with Repository Operations, Radiological Safety, and Repository Design.

 

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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