ENERGY

1. ENERGY NUCLEAR POWER

2. 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

3. 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

4. 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

5. 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

6. 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

7. 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

8. 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

9. 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

10. 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

11. 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

12. 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

13. 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

14. 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.

15. 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

16. 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

17. 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

18. 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

19. 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

20. 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