nuclear waste. high /low level waste low level waste: generated at hospitals, educational...

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