nuclear waste. high /low level waste low level waste: generated at hospitals, educational...
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Nuclear Waste
High /Low Level Waste
• Low level waste: generated at hospitals, educational facilities, nuclear power plants and industry.
• Examples: radio-chemicals, contaminated gloves, papers, machine parts etc.
• Usually disposed of in shallow trenches at privately owned sites in Nevada, South Carolina, Utah and Washington.
Low Level Waste disposal
High Level Radioactive Waste
• Two major categories:• 1) Fission Products: elements that result
from the fission process. A couple of important examples are 137Cs and 90Sr.
• 2) Actinides: Formed by neutron absorption by the original fuel. Elements with Atomic numbers greater than 88. Extremely toxic chemically as well as being radioactive. Example: 239Pu.
After 600 years, radioactivity has dropped by a factor of over 10,000.
A reasonable storage time is 1000 years.
• The largest producer of radioactive waste is the military defense programs
• 80,000,000 gallons of liquid waste are stored at Hanford, Washington. (500,000 gallons leaked into the ground over a number of years.)
• The waste from 1 years operation of a 1000MW plant is approximate 2 m3.
Spent nuclear fuel is currently stored on site in pools
Long Term Disposal
Yucca Mountain
• The Nuclear Waste Policy Act (1982) and its Amendment Act (1987) established a national policy for nuclear waste disposal.
• In 1987 the Yucca Mountain, Nevada site was selected as the primary candidate for the long term deposit site.
• The site was extensively evaluated
It just looks like a place to store nuclear waste.
Basic Characteristics
• The rock formation is 13 million year old volcanic tuff.
• Very dry climate (less than 6 in of rain per year.)
• The water table is 1700 feet down.
• Groundwater travel laterally about 1mile in 3400 to 8300 years.
• Nearest surface water is 30 miles away.
• Tuff can trap any radionuclides that may leak by adsorption within the rock.
• The government already owns the site.
• Funding ended for the site in 2011, and the site has been closed.
Plans called for multiple barriers
• Waste is first encapsulated in glass or ceramic beads.
• Waste is placed in stainless steel canisters
• Canisters are located in storage rooms in stable rock formations. Rooms are backfilled with material to retard penetration of water
Routes for Nuclear Waste
• Funding ended for the site in 2011, and the site has been closed.
• The Government Accountability Office (GAO) stated that the closure was for political reasons
• Non US governmental organizations currently have no long term storage sites for high-level waste
• The US government stores waste at the Waste Isolation Pilot Plant in New Mexico.
• Other waste is stored on-site.
Current Nuclear Waste Storage Sites