ENERGY NUCLEAR POWER

The Energy Of Atomic Fission Definitions Proton - a positively charged subatomic particle Neutron - a negatively charged subatomic particle Isotope - atom that exhibits variation in its mass number Mass number - sum of the neutrons plus the protons in an atom Atomic number - # of protons found in the nucleus Atomic weight - average of the atomic masses of all the element's isotopes Fission - the act or process of splitting into parts Fusion - a nuclear reaction in which nuclei combine to form more massive nuclei with the simultaneous release of energy

The Energy Of Atomic Fission Fuels for Nuclear Reactors Natural fuels U235 is the only natural isotope of any element that is spontaneously fissionable 92U238 - 99.283% of all U 92U235 - 0.711% 92U234 - 0.006% U235 is the initial fuel for all fission reactors 1 gram of U235 equals 2.7 metric tons coal or 13.7 bbls oil

The Energy Of Atomic Fission Fuels for Nuclear Reactors Man made fuels U238 and Th232, fertile materials, can be made to combine with a neutron to make a useful fuel 92U238 + neutron → 94Pu239 fuel 90Th232 + neutron → 92U233 fuel

The Energy Of Atomic Fission The Nuclear Fuel Cycle U235 must be enriched from 0.711% to 3.0% This is done with UF6 gas After enrichment the U is made into UO2 ceramic pellets These pellets become fuel rods which last 3 years They are then stored in water at the reactor site

The Energy Of Atomic Fission Types of Reactors The Light Water Reactor LWR This is a burner type reactor which simply consumes U235 and produces neutrons, heat, and waste Reactor ultimately produces steam to drive the turbine A typical LWR has 100 tons of enriched U fuel - 40,000 rods Control rods are neutron absorbing B or Cd

The Energy Of Atomic Fission Types of Reactors Breeder Reactors These reactors convert U238 and Th232 into fuel France, Japan, the United Kingdom, Germany and the USSR are developing breeders The United States started research in 1948 on the LMFBR Low U costs will probably delay breeders in the U.S. until after 2000

Problems Of Uranium Mining Lung Cancer among the Miners NRC and the U.S. Public Health Service found a higher incidence of lung cancer among miners Waste from Uranium Milling 865 gallons of toxic chemical waste form per ton of ore treated This waste was discharged into rivers or seeped into the Earth in the 1960's

Problems Of Uranium Mining The Problem of Tailings 100 million tons of radioactive sand exists at 30 mills in the western U.S. 5000 homes in Grand Junction, CO were built with this sand Tailings have washed into Lake Powell and Lake Meade

Problems At The Reactor Site Geological Problems Extremely extensive geological investigations are made Reactors still end up too close to fault zones Diablo Canyon - PG&E Bodega Bay

Problems At The Reactor Site Human and Mechanical Error Three Mile Island - March 28, 1979 The feed water pump to the reactor core was accidentally closed rods immediately went in and the reactor partly stopped Human error resulted in the emergency cooling system being shut off for 2 hours Core overheated to 1500ºC one billion dollars damage

Problems At The Reactor Site Human and Mechanical Error Chernobyl - April 26, 1986 Human errors resulted in a explosion and radiation release 100,000 people may be contaminated

The Disposal Of Nuclear Waste What the Waste Products are Fission products Over 30 elements form most have half lives of <100 years emit beta and gamma radiation Some are water soluble and biologically active Transuranium products heavier than U and form by neutron capture have half lives >1000 years act as heavy metal poisons Waste must be stored for 250,000 years

The Disposal Of Nuclear Waste How Much Spent Nuclear Fuel is there in the U.S.A. Remember that there is also military and medical waste By the year 2000 there will be 40,000 metric tons stored at 70 locations By 2035 the total will be 85,000 metric tons The Nuclear Waste Policy Act of 1982 selected Yucca Mountain, NV as the only depository site in the U.S.

The Disposal Of Nuclear Waste Criteria for a Storage Method isolation from the biosphere for 250,000 years sabotage and accident free for 250,000 years safe from natural disasters for 250,000 years must not involve large land areas or resources must be resistant to erosion, Earthquakes, and volcanism handling and transport must be fail safe economically and technically possible

The Disposal Of Nuclear Waste Possible Storage Methods Rocket transport of the waste dangerous and costly Continue present tank storage indefinitely leakage of dangerous waste has already occurred Placement in deep chambers of granite waste would boil, dehydrate, melt the surrounding rock and seal itself leakage along fractures is possible

The Disposal Of Nuclear Waste Possible Storage Methods Injection in Deep Wells Waste would be mixed with cement or injected directly under high pressure into impermeable layers Many dangers high pressure injection is dangerous high temperature could drive the waste out into other layers could lubricate faults Deposition in Trenches technically difficult to assure no leaks

The Disposal Of Nuclear Waste Possible Storage Methods Deposition under polar ice caps Waste containers melt to the bottom of the glacier and remain stationary Violates international treaties Salt Mine Waste Storage salt indicates a dry environment salt flows and seals fractures salt dissipates heat Element Transmutation Eventually gamma ray lasers will convert dangerous elements into safe ones

The Disposal Of Nuclear Waste What is to be done? Find a public repository for nuclear waste Because of public fear this is probably a doomed and costly effort Reprocess spent fuel to reduce the volume of waste This raises more fear because Pu may be diverted to nuclear weapons A permanent repository will still be needed

The Disposal Of Nuclear Waste What is to be done? Continue on-site, dry-tank storage This is the only reasonable political solution This can be done for a 100 years and will allow time for: improved technology decline of public fear