Nuclear Power Generation & Emergency Preparedness

1. Nuclear Power Generation& Emergency Preparedness Health Physics Society Power Reactor Section

2. 103 Nuclear Power Reactors

3. Steam Engines

4. Outline • Electric Power Generation • Why Nuclear? • What About Accidents? • Safety By Design and Operation • What About Drill Scenarios?

5. Electricity: A Vital Resource

6. Sources of Power (2002) Source: EIA - Updated 11/03

7. COAL HYDRO NATURAL GAS SOLAR & WIND cheap and abundant but source of greenhouse gases clean but seasonal and no new sources cleaner than coal but limited supply renewable but expensive, low energy density, and intermittent Pros & Cons

8. NUCLEAR high energy density no air pollution small, contained waste But what about… safety, security, and waste disposal ? Why Nuclear?

9. High Energy Density Each person in the United States uses either: 4 tons of coal or a few ounces of uranium • 1 pellet = 150 gallons gasoline • 1780 pounds coal • 16,000 ft3 natural gas • 2.5 tons wood

10. No Air Pollution

11. Waste Contained in Used Fuel Assemblies, Cooling-off In Pools

12. Loaded into Steel Containers, Stored in Concrete Casks

13. Steel Containers Buried Deep Underground

14. Waste Hazard Decreases Over Time

15. Nuclear Safety Record • 440 civil nuclear reactors in 30 countries sharing operating experiences (http://www.world-nuclear.org/index.htm) • Impressive safety record covering 12,000 reactor-years of operating experience • Two nuclear accidents: • TMI (1979) • Chernobyl (1986)

16. Three Mile Island (TMI) • March 28th 1979, Unit 2 reactor trips at 4 AM. (The movie “China Syndrome” is playing in theaters) • Pressurer relief value sticks open, lose of cooling accident (LOCA) begins. • Hampered by inadequate training and instrumentation, operators shut off emergency core cooling. • By 6:30 AM, blocking value is closed, shutting off the loss of coolant but … • The water level has fallen below the top of the reactor core. The fuel rods containing the uranium fuel pellets melt and release radioactive gas into the Containment Building.

17. TMI: Hydrogen “Bubble” • When the fuel rods melt, hydrogen gas is generated. • A “bubble” of hydrogen gas collects in the reactor head. • Fear that the hydrogen could explode result in confusion, panic. About 150,000 people evacuate. • However, the hydrogen explosion was never possible (not enough oxygen) • Major lessons: • Better operator training • Better emergency planning

18. TMI: Consequences • No one killed, no one injured. • Offsite radiation is minimal, a small fraction of natural background radiation. • Public confidence is severely damaged. • Many health effects studies have been conducted. In 1996, a U.S. District Court dismisses all lawsuits finding no evidence of harm. • Improvements to operator training, instrumentation, and emergency plans are now required.

19. Chernobyl

20. Chernobyl • April 1986 disaster at Chernobyl in the Ukraine was a result of a dangerous reactor design and weak operational controls. • Weak Operational Control: • Poorly trained operators were performing a dangerous and unauthorized “test”. • Dangerous Reactor Design: • A “positive” temperature coefficient of “reactivity” resulted in a huge power surge that cause water to flash to steam, blowing the cover plate off the top of the reactor… • Broken pipes spilled water onto the hot “graphite” moderator, which bursts into flames.

21. Flawed Reactor Design graphite core & unstable reactor

22. Environmental Pathways 82% of the iodine exposure was avoidable

23. Chernobyl: Consequences • 31 workers, mostly fire fighters are killed largely due to acute radiation exposure. • Huge release of radioactive material, distributed around Europe. • World confidence is severely damaged. • The Whole Health Organization has linked hundreds of child thyroid cancers to the accident (10 deaths), but no detectable increase in other cancers. • The greatest damage was from fear (psychological), NOT radiation.

24. Can Chernobyl Happen Here? • Reactor Design: Apples & Oranges • Positive temperature coefficients of reactivity • Graphite core that catches fire and burns for days • No containment building • Institutional Controls: Apples & Oranges • No strict operating license • No strict regulatory oversight • Lesson: Never Take Safety For Granted

25. Nuclear Safety • Design and Construction • Operation and Training

26. Safety By Design: Low “Enrichment” • Fission “chain reaction”: E = m * c2 • U-235 atoms fission. 5% in fuel, 95% in bombs.

27. Safety By Design: Fuel Rods Typical values: • The uranium fuel is made of solid ceramic pellets. • The fuel pellets are sealed inside 13’ long zirconium alloy rods. • 236 rods in each assembly • 217 assemblies in the reactor core

28. Safety By Design: Reactor Vessel Typical values: • Weight: 400 tons • Thickness: 8 inches Fuel Assemblies (Core)

29. Safety By Design: PWR Containment Initial Construction Completed Concrete Dome

30. Layers of Protection Against 9/11

31. Safety By Design: Reactor Control • Automatic shutdown system relies on gravity • Negative temperature & pressure coefficients of reactivity* • Controls rods maintain maximum shutdown potential

32. Safety By Design:Redundant Safety Systems • Reactivity Control • Core Heat Removal • “RCS” Inventory Control • “RCS” Heat Removal • Containment Isolation

33. Regulatory Control Nuclear Regulatory Commission Headquarters in Rockville, Maryland (www.nrc.gov)

34. NRC Regulatory Functions

35. This IS Rocket Science • Final Safety Analysis Report (FSAR) • Volume 15: Accident Analysis • Design Basis Accidents (Worst Case Scenarios): • Loss of Cooling Accident (LOCA) • Steam Generator Tube Rupture (SGTR)

36. What Can Get Released? • Noble gas fission products • Chemically inert (xenon) • Volatile fission products • Chemically reactive (iodine) • All other fission products • Remain in solid form

37. Beyond “Worst Case Scenarios” • EP drills must exercise the emergency plan, requiring an unbelievable sequence of events. • Nuclear Engineering uses the science of: • “Probabilistic Risk Assessment” • Probability of an typical “EP Scenario”: • “1 in 10 billion”

38. Summary • Benefits of nuclear power include no air pollution and low volume of contained waste. • We’re here today because of the lessons-learned at TMI. • Because of differences in design, the Chernobyl disaster has little relevance to the safety of U.S. nuclear power plants. • U.S. nuclear plants are safe through design, operation, and strict regulatory control. • EP Drills must use unrealistic scenarios to exercise our Emergency Plan.

39. Thanks …for your interest and patience !