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Understanding the Japanese Reactor Accident!

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  1. Understanding the Japanese Reactor Accident! Dr. James F. Wright HT3R Director University of Texas of the Permian Basin Japan Earthquake/Tsunami

  2. Japan Earthquake/Tsunami

  3. Understanding theJapanese Reactor Accident! • Background on Nuclear Power (GE Mark I BWR) • Chronology of Events • Effects • Historical Perspective • Lessons Learned Japan Earthquake/Tsunami

  4. Understanding theJapanese Reactor Accident! • Background on Nuclear Power (GE Mark I BWR) • Chronology of Events • Effects • Historical Perspective • Lessons Learned Japan Earthquake/Tsunami

  5. The “Natural”Advantage! The fission of one atom of Uranium produces 70-100 million times the energy produced from the combustion of one atom of Carbon! Japan Earthquake/Tsunami

  6. Requirementsfor a “Nuclear Power Reactor” • Provide cost-effective “base-line” electricity with a high duty factor (>90%) for up to 60 years • No noise, smoke, etc. • Respect the environment, health & safety of fellow-citizens Japan Earthquake/Tsunami

  7. Requirementsfor Nuclear Fuel • Cannot be made into fissile weapons by “reasonable” technology without harm • Can be readily mined, milled & manufactured • Fabricated into sturdy, stable fuel “pins” that are insoluble in hot water, contain fissile material, and inert to most common chemicals • Stand high-temperatures (clad “ceramic”) Japan Earthquake/Tsunami

  8. U.S. Nuclear Fuel Cycle US Version of Fuel Cycle Japan Earthquake/Tsunami

  9. GE Mark I Japan Earthquake/Tsunami

  10. GE Mark I BWR • Units in US: • First US unit completed: 1969 • Last US unit completed: 1986 • Units in US – 23 Japan Earthquake/Tsunami

  11. UO2Fuel Pellet Ceramic fuel (UO2) encased in a Zr alloy “cladding” Japan Earthquake/Tsunami

  12. ZirconiumCladding is the Solution • Relatively porous to neutrons • Insoluble in boiling water • No chemical reactions with UO2 at “standard” operating conditions • Survive in High Temperatures found in core of nuclear reactor (a few hundred degrees C) Japan Earthquake/Tsunami

  13. But, …Zirconiumis also the Problem! When Zr cladding reaches approximately 2,200o F in the presence of water it undergoes an exothermic chemical reaction: Zr + 2H2O → ZrO2 + 2 H2 + Heat Japan Earthquake/Tsunami

  14. Containment“5 Levels of Shielding” • Fuel – Zircaloy Cladding • Pressure Vessel – 6-in steel with 316L SS on both sides • Primary – 1-in thick steel • Secondary – Steel-reinforced, pre-stressed concrete 4 to 8 ft thick • Reactor Building – Steel-reinforced, pre-stressed concrete 1 to 3 ft thick Japan Earthquake/Tsunami

  15. Also,……. A Nuclear Reactor is a “heat source that keeps on heating” after it is turned off! Japan Earthquake/Tsunami

  16. Daiichi PlantDesign Basis Limits 1 1 1 1 1 1 1 1 1 * Reactors and backup power sources were 10m to 13 m high Japan Earthquake/Tsunami

  17. Simplein Concept • Keep it “safe” • Keep Temperature of both “spent fuel” and “existing fuel” < 2,200o F at all times Japan Earthquake/Tsunami

  18. Mark I Fuel 548 Fuel Assemblies in Mark I (4,734,720,000 Fuel Pellets!) Japan Earthquake/Tsunami

  19. Japan Earthquake/Tsunami

  20. Japan Earthquake/Tsunami

  21. Japan Earthquake/Tsunami

  22. Understanding theJapanese Reactor Accident! • Background on Nuclear Power (GE Mark I BWR) • Chronology of Events • Effects • Historical Perspective • Lessons Learned Japan Earthquake/Tsunami

  23. 2011 TōhokuEarthquake • March 11, 2011 • 2:46 PM Japan Standard Time • 9.0 magnitude (Richter Scale) • ~45 mi E of Oshika Peninsula of Tōhoku (near Sendai) • Hypocenter ~19.9 mi beneath sea surface Japan Earthquake/Tsunami

  24. Earthquake Japan Earthquake/Tsunami

  25. Japan Earthquake/Tsunami

  26. ImmediatelyAfter Earthquake • All reactors in Japan automatically shut down • Emergency power came from power grid if available, or else emergency backup generators, to operate emergency cooling systems (for cores and spent fuel pools) • Cooling Water was flowing • BU battery power was available (8 hr supply) Japan Earthquake/Tsunami

  27. Tsunami A huge Tsunami (up to 46 ft high!) hit the coast nearest the epicenter (with a perpendicular vector “view” of a “point source” impulse) Japan Earthquake/Tsunami

  28. Japan Earthquake/Tsunami

  29. STATION BLACKOUT!!! Japan Earthquake/Tsunami

  30. StationBlackout • Loss of all “off-site” Power AND • Loss of all “on-site” generating capability AND • Loss of all “on-site” battery power Japan Earthquake/Tsunami

  31. StationBlackout AND • Diesel Generators were destroyed AND • Emergency pumps were destroyed AND • Piping, valves, etc. were destroyed Japan Earthquake/Tsunami

  32. The nightmare started! Japan Earthquake/Tsunami

  33. Understanding theJapanese Reactor Accident! • Background on Nuclear Power (GE Mark I BWR) • Chronology of Events • Effects • Historical Perspective • Lessons Learned Japan Earthquake/Tsunami

  34. Primary Issues • Loss of power • No working pumps • No water Japan Earthquake/Tsunami

  35. Temperaturesstarting Rising • All fuel (in Reactors and spent fuel pools*) started overheating • H2 Production in cores • Vented Reactor to Primary containment • Vented to Primary to Secondary containment • Exploded! (in Operating Units 1, 3, & 2-SP) * All but 1 spent fuel pools inaccessible to humans! Japan Earthquake/Tsunami

  36. Japan Earthquake/Tsunami

  37. Status0700 CDT 4/1/2011 • Contaminated water in turbine buildings of Units 1, 2, 3, & 4 is being removed • Freshwater injections continue to cool Units 1, 2, and 3 • Freshwater is spraying cooling water on spent fuel • Instances of slightly contaminated milk are surfacing in the US (<1.0 pCi) – 50 mCi is “reportable level” in US • Japanese Government is taking over Fukushima sites (from TEPCO) Japan Earthquake/Tsunami

  38. Understanding theJapanese Reactor Accident! • Background on Nuclear Power (GE Mark I BWR) • Chronology of Events • Effects • Historical Perspective • Lessons Learned Japan Earthquake/Tsunami

  39. Past SignificantAccidents • Chernobyl 1986 (Level 7) • Kyshtym (Chelyabinsk) 1957 (Level 6) • TMI 1979 (Level 5) • Fukushima (Level ?) Japan Earthquake/Tsunami

  40. a Chernobyl - 1986 Chelyabinsk (Kystym) - 1957 TMI - 1979 A a Japan Earthquake/Tsunami

  41. Radiation Dose • rem – unit of “radiation dose equivalent for man” [absorbed dose (rads) x Weighting Factor] • Max dose for public: 100 mrem/yr • “Whole Body” Dose Equivalents • μrem to mrem: insignificant • <50 rem: subclinical except for minor blood changes • 50 to 200 rem: may cause illness but rarely fatal • 200 to 1,000 rem: serious illness , poor outlook at high end • > 1000 rem: almost invariably fatal • 1 Sievert = 100 rem Japan Earthquake/Tsunami

  42. Radiation DoseIn Context Average dose in US is ~300 mrem/year Japan Earthquake/Tsunami

  43. Understanding theJapanese Reactor Accident! • Background on Nuclear Power (GE Mark I BWR) • Chronology of Events • Effects • Historical Perspective • Lessons Learned Japan Earthquake/Tsunami

  44. Work In Progress! Japan Earthquake/Tsunami

  45. More to Learn… • Several National and International Panels will be convened to examine both the accident and the response to the accident • Little, if anything, will be changed in the US …. The NRC is still the Gold Standard in the world! Japan Earthquake/Tsunami

  46. “Lessons Learned” to Date • Absolute passive safety for cooling is ultimate solution and mandatory! • Stage Emergency Batteries, Generators, pumps, etc. nearby but “safe” • Reassess preparedness and training Japan Earthquake/Tsunami

  47. “Best” Factual Resource Nuclear Energy Institute (NEI): http://nei.cachefly.net/newsandevents/information-on-the-japanese-earthquake-and-reactors-in-that-region/ Japan Earthquake/Tsunami

  48. Pu Inventory • >4,000 Fuel Assemblies at Daiichi Site • Reactors • Spent Fuel Pools • Only 32 are MOX in Reactor 3 (<6% in reactor 3 and <1% for the site!) • ~4,734,720,000 “fuel pellets” in a Mark I core Japan Earthquake/Tsunami

  49. Fission Immediate: ~180 MeV per fission Delayed: ~20 MeV per fission Burning Coal: ~2-3 eV per atom Japan Earthquake/Tsunami

  50. GeneralNuclear Fuel Cycle Japan Earthquake/Tsunami