Finding a Space for Waste ¡noah!NCSS7/27/06

Alternative Energy Sources

On-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 Rods  Only <3% 238 U actually used in “once-through” open fuel cycle.  Spent fuel (right) is a form of HLW and is the primary concern for 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 seabed Burial hundreds of meters under the middle of the tectonic plates ~70% of Earth’s outer core = an essentially limitless storage capacity Funding for research cut 20 years ago to focus on Yucca 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 10 5 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 Pu 4+ (most abundant form) is insoluble and therefore settles as sediment in groundwater instead of being transported CONS Possible for Pu 4+ to transport by binding to natural colloids and microorganisms Np 5+ 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.