1. NUCLEAR ENERGY Historical:  Late 1800’s Pierre and Marie Curie determined that uranium minerals emitted invisible radiation capable of passing through solid objects.  Subsequently, it was determined that the radiation was a result of atomic disintegration as atoms of radioactive minerals break down spontaneously over time (DECAY)

2. RADIOACTIVE DECAY Parent radioactive material decays to daughter material. 238 U 4 He + 234 Th Radioactive decay is described in terms of half life – the time it takes for ½ of the radioactive atoms to decay = Fission (break apart and lose mass). Fusion is when atoms combine to form new atoms with less mass. 1 H + 1 H 2 He (Thermonuclear rxn in the sun)

3. FUSION VS. FISSION Atomic Mass HFe U (1)(26) (92) Atomic Number l Fusion Fission E=MC 2 “Lose mass to get more energy out”

4. How Can We Fuse? Need 1,000,000 degrees! Brookhaven National Labs has initiated fusion reactions,but can’t sustain them for more than 1 minute! BENEFIT: waste product is helium…the stuff you put in children’s balloons! No air pollution. We’re living in the BF years! We’re living in the years of fission nuclear power plants and mass consumption of fossil fuels and tremendous air pollution.

5. IONIZING RADIATION Definition: Emissions from radioactive nuclei collide with other atoms or molecules and hence ionizes that atom or molecule. Three types of ionizing radiation:  Alpha (  ) radiation – physically identical to the nuclei of He atoms 2P, 2N. They travel 10,000 mi/s and interact with other atoms. When alpha particles make contact with skin cells, the energy dissipates. Our skin protects us. We are at risk when these ions are inhaled, ingested, or absorbed in a wound.

6.  Beta (  ) Radiation – electrons that are emitted from a radioactive atom. Interaction with other molecules is less frequent than with  particles. They lose energy at a much slower rate and can penetrate human tissue. Internal organs are usually protected. Exposed organs such as eyes are very sensitive to  damage.  Gamma (  ) Radiation – invisible, electromagnetic rays emitted from the nucleus of radioactive atoms and are composed of photons. The dose of gamma radiation received by unprotected human tissue can be significant.

7. HOW DOES A NUCLEAR FISSION REACTOR WORK?

8. THERMAL REACTOR

9. PARTS OF THE REACTOR  Core – 35,000 – 40,000 long, thin fuel rods each packed with pellets of uranium oxide fuel. Each pellet is the size of a cigarette and is packed with 97% of 238 U (nonfissionable) and 3% 235 U (fissionable).  Control Rods – are moved in/out of the reactor core to absorb neutrons and regulate the rate of fission and the amount of power the reactor produces.  Moderator (liquid water, graphite, or deuterium) – slows down the neutrons emitted by the fission process so that the chain rxn can continue.

10. PARTS OF THE REACTOR  Coolant- Usually water, circulates through the core to remove heat to keep the fuel rods and other materials from melting and to produce the steam to turn the turbines for generating electricity.  After 3-4 years, the concentration of fissionable uranium ( 235 U) in the fuel rods becomes too low to continue the chain rxn OR the rods become damaged from ionizing radiation. They are removed and placed in large, concrete lined pools of water to act as a shield/coolant.

11. WHAT DO WE DO WITH NUCELAR WASTE? High Level Radioactive Waste – gives off large amounts of ionizing radiation for a short time and small amounts for a long time. It must be stored for a very long time, 240,000 years if plutonium ( 239 Pt) is not removed by processing. Reprocessing – removal of Pt from fuel rods. The remaining radioactive waste must be stored for at least 10,000 years. USA does NOT do this anymore due to high operating costs and ample supplies of uranium.

12. Long-Term Waste Storage Facilities Carlsbad New Mexico – Waste isolation Pilot Plant (WIPP); a government run underground storage facility for waste from nuclear weapons. Cost = 2 billion dollars. Yucca Mt. – 100 miles north of Ls Vegas. Will be designed to accept waste from commercial nuclear reactors. Problems: active fault zone, water seepage, non-uniform strata. 1996 USA accepted and manage highly spent fuel rods from 40 countries to prevent them from extracting highly enriched uranium for nuclear weapons! Terrorists only need 1kg of plutonium oxide to contaminate an are 3 mi 2 with dangerous ionizing radiation for 100,000 year!

13. LOW-LEVEL RADIOACTIVE WASTE Low –Level Radioactive Waste – gives off small amounts of ionizing radiation and must be stored safely for 100-500 years before decaying to levels that don’t pose a health risk to the public. 1940’s – 1970’s USA and most other countries put LLRW into steel drums and dumped it into the ocean. (Pakistan and UK, still do) Since 1970 – LLRW has been buried in government-run landfills (2 remaining) and in above ground storage containers.

14. OTHER PROPOSALS Bury it deep in the ground Shoot it into space or the sun - abandoned Bury it under Antarctic ice sheet or Greenland - abandoned Dump into descending subductions zones in the deep ocean – active study Change it into less harmful isotopes – not achieved yet

15. HOW SAFE ARE NUCLEAR POWER PLANTS? Case Study: Three Mile Island March 29, 1979 - #2 reactor in Harrisburg, PA lost its coolant water b/c of a series of mechanical failures and human operator errors for safety measure. The reactor core became partially exposed and 50% of it melted and fell to the bottom of the reactor. Unknown amounts of radiation was released into atm. 50,000 people evacuated, 1.2 billion in law suits, increase in cancer rates over the years (stress and radiation).

16. CHERNOBYL April 26, 1986 – Total meltdown of a graphite moderated nuclear fission power plant. Released enormous amounts of radiation due to loss of coolant around fuel rods and they melted through the core. Health Effects: Thyroid, skin, liver, ovaries, muscles, lungs, spleen, kidney, bone. Caused mutations and cancer.

17. LIFESPAN OF A REACTOR After 15-40 years, a nuclear reactor becomes dangerously contaminated with radioactive material. They can be decommissioned or retired by: 1.Dismantling and storing large volumes HLRW in appropriate storage facilities (don’t exist). 2.Construct a physical barrier for security for 30-100 years before the plant is dismantled. 3.Enclose plant in a tomb that must last for thousands of years.

18. NUCLEAR REGULATORY COMMISSION NRC assessed US reactors and concluded that there is a 15-45 % chance of a complete core meltdown. Public doesn’t trust NRC and DOE b/c they7 destroyed documents, obstructed investigations and gave advance notice to facility operators before “surprise inspection visits”

19. ADVANTAGES OF NUCLEAR POWER  No air pollutants emitted.  Land disturbance is low when no accidents are involved.  Construction and backup safety systems decrease the likelihood of a catastrophic event.  Chernobyl only caused the premature deaths of 32,000 people; coal burning causes premature deaths of 65,000 – 200,000 people in the USA each year!

20. DISADVANTAGES OF NUCLEAR ENERGY 1.Always the danger of a metldown 2.Waste disposal? 3.How do we effectively decommission the facilities after only 17 years of use? 4.Only 17% efficient 5.Extremely high costs associated with using “safe technology”.

21. WHAT IS THE FUTURE OF NUCLEAR? 1.Breeder Nuclear Fission Reactors – generate more nuclear fuel than they consume by converting non- fissionable 238 U to 239 Pt. 2.Liquid sodium is used as a coolant and is very explosive when it reacts with air. 3.Nuclear Fusion. Not yet! We’re still in the BF yras.