finding a space for waste

Finding a Space for WasteFinding a Space for Waste

¡noah!¡noah!

NCSS NCSS

7/27/067/27/06

Alternative Energy Sources

Alternative Energy Sources

Alternative Energy Sources

Alternative Energy Sources

On-Site Waste StorageOn-Site Waste Storage

“temporary” holding tanks at reactor sites are filling up. Some of the waste has been kept there over 3 decades!

Nuclear Reactor Fuel RodsNuclear Reactor Fuel Rods

Only <3% Only <3% 238238U actually U actually used in “once-through” used in “once-through” open fuel cycle.open fuel cycle.

Spent fuel (right) is a Spent fuel (right) is a form of HLW and is the form of HLW and is the primary concern for primary concern for permanent disposal.permanent disposal.

Yucca Mountain

• ~90 miles NW of Las Vegas, Nevada• Capacity: 77,000 tons--will be full by 2020 (scheduled

to open in 2017)

will only be part of the solution.

Under the seabedUnder the seabed

• Burial hundreds of meters under the middle of the Burial hundreds of meters under the middle of the tectonic platestectonic plates

• ~70% of Earth’s outer core = an essentially ~70% of Earth’s outer core = an essentially limitless storage capacitylimitless storage capacity

• Funding for research cut 20 years ago to focus on Funding for research cut 20 years ago to focus on Yucca MountainYucca Mountain

Considering a Disposal Area: Worst Case Scenarios

• For seabed: can sea creatures carry leaked waste to ocean surface?

• Experiments show that radionuclides would not travel more than a few meters through the seabed clay in 105 years!

WCS for Yucca Mountain Groundwater

contamination is the biggest concern

YM is 300 meters above the water table

Leaked waste could be transported by rain water to water table, so chemistry of the waste must be considered

Pros & Cons for Yucca Mountain’s WCS

PROS

•Volcanic Tuff contains zeolite

•Pu4+ (most abundant form) is insoluble and therefore settles as sediment in groundwater instead of being transported

CONS

•Possible for Pu4+ to transport by binding to natural colloids and microorganisms

•Np5+ is soluble and is not stopped very well by zeolite

Vitrification

Puts radioactive waste into glass or ceramic lattice

immobilized, can’t transport through water

Does not shield radiation, so canisters still have to be used

Enormous cost: special plants built/designed only to produce glass logs, can only build one log/day, and each log costs ~$1.4M

Acknowledgements:

me.