Energy: Nuclear Energy
Part 2

EVPP 111 Lecture

Dr. Largen

• Cautionary Tale of Chernobyl
• Nature of nuclear energy
• History of Nuclear Energy
• Nuclear reactors
• Nuclear fuel cycle
• Nuclear weapons
• Concerns about nuclear energy
• Waste disposal

• Nuclear fuel cycle
• series of actions/activities involved in using nuclear fuels to generate energy
• steps
• mining ore
• milling ore
• fuel fabrication
• installing and using fuel rods
• disposing of waste

• mining ore
• low-grade uranium ore
• contains ~0.7% fissionable U-235
• must be enriched
• milling ore
• extracts uranium from ore
• concentrates the U-235
• process
• "yellowcake"
• fuel fabrication
• pellets sealed in metal fuel rods ~4m long
• installing and using fuel rods
• raised or lowered to control reaction
• after ~3 years, considered "spent"
• disposing of waste
• both low- and high-level waste is generated
• must be stored

• each step
• involves transport of radioactive materials
• presents possibility of accident or mishandling
• poses health and environmental concerns

• Nuclear weapons
• nuclear power industry is outgrowth of nuclear weapons industry
• environmental contamination around facilities
• DOE is responsible for 8600 km² of properties
• contaminated sites
• underground storage tanks
• 55-gallon drums of radioactive, hazardous or mixed waste in storage
• sites where wastes are moving through soil
• low- and high-level radioactive wastes
• importance has been reduced
• disposal of nuclear weapons

• Concerns about nuclear energy
• human health and environmental impacts related to
• release of radioactive materials at a power reactor
• Three Mile Island
• Chernobyl
• accidents/mishaps during production and transportation of fuel
• disposal of waste
• text states
• not great cause for concern related to reactor operation
• area of most concern is storage facilities for spent fuel
• US Nuclear Regulatory Commission (NRC) estimates
• 15-45% chance of a complete core meltdown at a US reactor during next 20 years
• 39 US reactors have an 80% chance of containment shell failure from a
• meltdown
• explosion of gases inside containment structures
• nearly half of US plants failed mock terrorist attacks against them

• Three Mile Island
• near Harrisburg, PA
• 3/28/79
• cause of accident
• valve malfunction
• human error
• result
• intense radiation released to interior of containment structure
• small amount of radiation was released into environment
• consequence
• average radiation exposure in surrounding area
• ~ 0.012mSv (~1% of natural background radiation)
• radiation levels near site
• on day 3, 12 mSv/hr was measured at ground level (average American receives about 2 mSv/year)
• days following Chernobyl accident, ~24,000 people received an average dose of 430 mSv
• Concerns about nuclear energy
• thermal pollution
• addition of waste heat to environment
• nuclear power plants
• 2/3 of heat is waste
• fossil fuel power plants
• 1/2 of heat is waste
• nuclear power plants
• use water in cooling processes
• cooling towers
• water
• decommissioning
• power plant life expectancy is 30-40 years (nuclear or otherwise)
• fossil fuel power plants
• demolished at end of life
• nuclear power plants
• not demolished
• decommissioned
• decommissioning
• two-stage process
• stage 1
• stage 2
• utilities have three options
• decontaminate and dismantle "immediately"
• wait 20-100 years, then dismantle plant
• entomb plant
• Waste disposal
• problem was not fully appreciated when world entered atomic age
• waste produced at each step in nuclear fuel cycle

• low-level waste
• give off small amounts of radiation
• must be safely stored for 100-500 years
• sources
• storage/disposal
• 1940’s-1970, in US
• steel drums, dumped in oceans
• ~90,000 drums
• currently
• steel drums, buried in approved sites
• high-level waste
• give off
• large amounts of radiation for short time
• small amounts of radiation for long time
• must be stored safely for at least 10,000 years
• ~240,000 if plutonium-239 is not removed by reprocessing
• sources
• storage/disposal
• is any method safe method for storing these wastes
• storage/disposal - proposed methods
• bury it deep underground
• favored strategy
• under study by all countries producing nuclear waste
• shoot it into space or into the sun
• bury it under Antarctic or Greenland ice sheet
• dump it into subduction zones in deep ocean
• bury it in thick deposits of mud on deep ocean floor in areas that tests show have been geologically stable for 65 million years
• change it into harmless, or less harmful, isotopes
• storage/disposal - US sites
• current - Waste Isolation Pilot Plant
• near Carlsbad, NM
• began accepting high-level waste in 1999
• in development - Yucca Mountain, Nevada
• unpopulated region
• near Nevada Test Site where several nuclear devices were exploded
• very dry area
• water table 600m (1968ft) below surface
• geologically stable (although seismic activity has been witnessed since its selection as site)
• work has begun, considered exploratory
• complete ~2015
• Bush signed resolution in July 2002 to allow construction to proceed

The End