CURRENT USE STATISTICS

HISTORY OF NUCLEAR ENERGY

NUCLEAR POWER CYCLE

Basics of Nuclear Power

History

Ernest Rutherford – split the atom in 1917Enrico Fermi – nuclear fission in 1934Scientists realized fission reactions could be

self-sustainingFirst man-made reactor – Chicago Pile-1 in

1943 (later part of the Manhattan Project)Stricter government regulation after WWIIMovement against nuclear power driven by

fear and history of nuclear accidents

Current use statistics

Worldwide - 2.1% of the energy and 15% of electricity United States, France, and Japan 56.5% of nuclear-

generated electricity Economics – large initial investment ($6-10 billion),

most economical to run plants for as long as possible or add reactors to existing plants

From the 2003 MIT study, “The Future of Nuclear Power”: “In deregulated markets, nuclear power is not now cost

competitive with coal and natural gas. However, plausible reductions by industry in capital cost, operation and maintenance costs, and construction time could reduce the gap. Carbon emission credits, if enacted by government, can give nuclear power a cost advantage.”

Nuclear fuel cycle

Exploration

Two uranium isotopes U-235 (0.71%) and U-238 (99.29%)

U-235 is a fissile isotope – fissions when hit by a free neutron

U-238 absorbs the free neutron to become U-239

U-238 become Pu-239, a fissile isotope, though natural radioactive decay

Uranium mining and processing

Open-pit (surface), underground, and in situ leaching mining techniques

Uranium ore in the United States ranges from 0.05% to 0.3% uranium oxide (U3O8)

Trace quantities of uranium in domestic phosphate-bearing deposits of marine origin

Uranium ore is ground and the uranium is extracted though chemical leaching

The resulting product, yellowcake, is sold as uranium oxide

Uranium ore Yellowcake

Uranium mining and processing

Uranium conversion

Uranium oxide converted to uranium hexaflouride, form required by most commercial uranium enrichment plants Solid at room temperature, gas at 57°C Conversion of only natural uranium (not enriched) Most uranium converted to UF6

Also convert to uranium dioxide (UO2) for reactors that do not require enriched uranium

Enrichment

Natural UF6 enriched to fissionable isotope Light-water reactor fuel enriched to 3.5% U-

235Various methods of isotope separation –

gaseous diffusion, gas centrifuge96% of byproduct is depleted uranium95% of DU is stored as uranium hexaflouride

Fabrication

Enriched UF6 converted into UO2 powder, which is processed into pellets

Pellets fired in sintering furnace, processed to be uniformly shaped

Pellets stacked into tubes of metal alloy and sealed, creating fuel rods (specific to reactor core)

For BWR and PWR, fuel rods bundled, given unique identification numbers (trace from manufacture to disposal)

Transportation

Most transports of nuclear fuel material occur between different stages of the cycle

Minimize radiation exposureSpecial handling for spent fuel and high-level

wasteSpent nuclear fuel shipping casks, shielding

techniques

In-core fuel management and interim storage

Array of cells, each cell is fuel rod surrounded by coolant (water)

Water or boric acid provide cooling (decay heat from residual radioactive decay) and shielding

After operating cycle, spent fuel discharged and usually stored in spent fuel pool

When spent fuel pool is filled, store cool aged fuel in dry storage facility (ISFSI)

Reprocessing

Fissile and fertile materials, such as U-235, Pu-239, and U-238, can be chemically separated and recovered from the spent fuel to be recycled for use as nuclear fuel

Mixed oxide fuel (MOX) – blend of reprocessed uranium, plutonium, and depleted uranium; behaves similarly to the enriched uranium Alternative to low-grade uranium used by light-water

reactors

Waste disposal “the Achilles heel of the nuclear industry”

Disposal of spent fuel and disposal of wastes from processing plants

Nuclear Waste Policy Act (1982) – Department of Energy responsible for waste disposal system for spent nuclear fuel and high-level radioactive waste

Deep geological repository for solid wastes, burningHigh-level radioactive waste – spent fuel (spent fuel

pools casks) Proposed storage at Yucca Mountain, no longer harmful after

10,000 years (EPA)Low-level radioactive waste – contaminated items,

hand tools, water purifier resins, and the reactor materials

Three Mile Island Accident

March 28, 1979 Combination of equipment

failure and confused plant operators.

Partial melting of fuel rod cladding.

Release of 43,000 curies of radiation released

Very strong containment shell built over reactor thanks to activists

No deaths or injuries-exposure to people in a 10 mile radius was about the same as receiving a chest x-ray

Lots of unknowns and fear at the time of the accident

Chernobyl

April 26, 1986 Ukranian republic of the USSR Monitoring turbine generators during at low power Reactor design made it unstable at low power and operators didn’t

take proper safety precautions A power surge caused two explosions which destroyed the reactor

core and blasted a hole in the roof of the reactor building 100-150 million curies released into atmosphere radioactivity estimated to be about two hundred times that of the

combined releases in the bombing of Hiroshima and Nagasaki Evacuation zone of ~1,100 square miles Over 75,000 people relocated Fallout devastated farmland, increased rates of thyroid cancer in

children Possibility of birth defects in future generations Plant completely shut down in 2000

Nuclear Proliferation

Plutonium is a waste product of nuclear fission- this can be used as further fuel or to make nuclear bombs

International Atomic Energy Agency (IAEA)- responsible for monitoring the world’s nuclear facilities and

preventing nuclear proliferation. The agency has acknowledges that there is a large amount of uncertainties and its impossible to detect all diversions of nuclear material.

Hanford

Nuclear weapons production beginning in 1943

Built along the Columbia river

Released large amount of waste into river/air

Affected 75,000 square miles

Hanford continued

Secrecy surrounded the operationIncreased citizen pressure finally allowed for release of

19,000 page document regarding Hanford’s historyBetween 1944-1972 approximately 2 million people

exposedDoses of I-131 increases risk of thyroid cancer, children

most susceptibleCurrently Hanford is the most contaminated nuclear

waste site in the U.S. and focus of largest environmental cleanup

53 million gallons of high level radioactive waste = 2/3 of nations high-level radioactive waste by volume

Hard to find data correlating cancer and exposure

High Level Radioactive Waste

Shearon Harris

New Hill, NC in Wake County

Single ReactorUntil 2003 nuclear waste

from two other plants were being shipped in for temporary storage on trains

Currently houses nation’s largest spent fuel pools.

These rods are packed in high density-run the risk of going critical

Long Term Storage at Yucca Mountain

90 Miles northwest of Las Vegas33 known geological faults in the vicinity 1992-5.6 earthquake 8 mile from site center which

damaged DOE project officeStorage to be well above water table but DOE

underestimated the time for water to seep from the surface

The earliest Yucca Mountain could open would be 2017 and by this point the amount of commercial waste produced will have surpassed the legal limit allowed in Yucca Mountain…a second repository would be needed

Yucca Mountain

“Low-level” Radioactive Waste

Very poor classificationExample: Includes medical waste as well leakages

from the reactor coreMost medical waste is hazardous for less than 8

months but reactor waste in the same category could be hazardous for hundreds of thousands of years

Trend has been to downgrade high grade waste. Saves money as regulations only require 100 years of passive institutional control.

NRC has planned for allowed/acceptable leakages (life on container does not last radioactivity lifespan) which are deemed as acceptable risks