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Three Mile Island Case Study

It is a case study about Three Mile Island nuclear power plant accident which happened on 1979 in Pennsylvania(USA)

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Three Mile Island Case Study

  1. 1. NUCLEAR ENERGY • IN THE 1950S AND 1960S, NUCLEAR POWER PLANTS WERE SEEN AS THE POWER SOURCE OF THE FUTURE BECAUSE THE FUEL THEY USE IS CLEAN AND PLENTIFUL. • IN THE 1970S AND 1980S, HOWEVER, MANY PLANNED NUCLEAR POWER PLANTS WERE CANCELLED AND OTHERS UNDER CONSTRUCTION WERE ABANDONED. • TODAY, NUCLEAR POWER ABOUT 14% OF THE WORLD’S ELECTRICITY.
  2. 2. •AN ISLAND LOCATED ON THE SUSQUEHANNA RIVER NEAR MIDDLETOWN PENNSYLVANIA. LOCATION http://www.ki4u.com/three_mile_island.htm
  3. 3. 3 MILE ISLAND REACTOR
  4. 4. In1979atThreeMileIslandnuclear powerplantinUSAacooling malfunctioncausedpartof the core to meltinthe #2reactor.TheTMI-2 reactorwasdestroyed. Theoperatorsbelievedthe relief valvehadshutbecauseinstruments showedthemthat a"close" signal wassentto thevalve. Thisinturn causedthe reactorto shutdownautomatically. The mechanical failures were compounded by the initial failure of plant operators to recognize the situation as a loss-of-coolantaccident due to inadequate training and human factors, such as human-computer interaction design oversights relating to ambiguous control room indicators in the power plant's user interface... Plant staff took a series of actions that made the problem worse. These further starved the reactor core of water flow and caused it to overheat. WHAT HAPPENED ?
  5. 5. In particular, a hidden indicator light led to an operator manually overriding the automatic emergency cooling system of the reactor because the operator mistakenly believed that there was too much coolant water present in the reactor and causing the steam pressure release The nuclear fuel began to melt through its metal container—about half the reactor core melted. Trace amounts of radioactive gasses escaped into the surrounding community as a geyser of steam erupted from the top of the plant. The melting fuel created a large hydrogen bubble inside the unit that officials worried might cause an explosion, releasing even larger amounts of radioactive material. WHAT HAPPENED ?
  6. 6. • TWENTY-EIGHT HOURS AFTER THE ACCIDENT BEGAN, WILLIAM SCRANTON THE THIRD, THE LIEUTENANT GOVERNOR, APPEARED AT A NEWS BRIEFING TO SAY THAT METROPOLITAN EDISON, THE PLANT'S OWNER, HAD ASSURED THE STATE THAT "EVERYTHING IS UNDER CONTROL". LATER THAT DAY, SCRANTON CHANGED HIS STATEMENT, SAYING THAT THE SITUATION WAS "MORE COMPLEX THAN THE COMPANY FIRST LED US TO BELIEVE." THERE WERE CONFLICTING STATEMENTS ABOUT RADIOACTIVITY RELEASES. SCHOOLS WERE CLOSED AND RESIDENTS WERE URGED TO STAY INDOORS. FARMERS WERE TOLD TO KEEP THEIR ANIMALS UNDER COVER AND ON STORED FEED AFTERMATH
  7. 7. • GOVERNOR DICK THORNBURGH, ON THE ADVICE OF NRC CHAIRMAN JOSEPH HENDRIE, ADVISED THE EVACUATION "OF PREGNANT WOMEN AND PRE-SCHOOL AGE CHILDREN...WITHIN A FIVE-MILE RADIUS OF THE THREE MILE ISLAND FACILITY." THE EVACUATION ZONE WAS EXTENDED TO A 20-MILE RADIUS ON FRIDAY MARCH 30. WITHIN DAYS, 140,000 PEOPLE HAD LEFT THE AREA. MORE THAN HALF OF THE 663,500 POPULATION WITHIN THE 20-MILE RADIUS REMAINED IN THAT AREA. • THE CRISIS ENDED THREE DAYS LATER WHEN EXPERTS DETERMINED THE HYDROGEN BUBBLE COULD NOT BURN OR EXPLODE. • ACCORDING TO A SURVEY CONDUCTED IN APRIL 1979, 98% OF THE EVACUEES HAD RETURNED TO THEIR HOMES WITHIN THREE WEEKS. AFTERMATH
  8. 8. 3 MILE ISLAND IMPACT Someradioactive gaswas released a couple of daysafter the accident, but not enough to causeany dose above background levels to local residents. There were no injuries or adverse health effects from the ThreeMile Island accident. TheThree Mile Island accident caused concerns about the possibility of radiation-induced health effects, principally cancer,in the area surrounding the plant. Becauseof those concerns, the Pennsylvania Department of Health for18 years maintained aregistry of more than 30,000 people who lived within five miles of ThreeMile Island at the time of the accident. The state's registry was discontinued in mid 1997, without any evidence of unusual health trends in the area. Thecleanup of the damaged nuclear reactor system at TMI- 2 took nearly 12 years and cost approximately US$973 million. Thecleanup was uniquely challenging technically and radiologically. Plant surfaces had to be decontaminated. Water used and stored during the cleanup had to be processed.
  9. 9. 3 MILE ISLAND IMPACT 100 tonnes of damaged uranium fuel had to be removed from the reactor vessel-- all without hazardto cleanup workers or the public. Acleanup plan was developed and carried out safely and successfully by a team of more than 1000 skilled workers. It began in August 1979, with the first shipments of accident- generated low-level radiological waste to Richland, Washington. In the cleanup's closing phases,in 1991, final measurements were taken of the fuel remaining in inaccessible parts of the reactor vessel. Approximately one percent of the fuel and debris remains in the vessel. Also in 1991, the last remaining water was pumped from the TMI-2 reactor. Thecleanup ended in December 1993, when Unit 2 received alicense from the NRCto enter Post Defueling Monitored Storage(PDMS). In October 1985, after nearly six years of preparations, workers standing on aplatform atop the reactor and manipulating long- handled tools began lifting the fuel into canisters that hung beneath the platform. In all, 342 fuel canisters were shipped safely for long-term storage at the Idaho National Laboratory, aprogram that was completed in April 1990.
  10. 10. • THE THREE MILE ISLAND INCIDENT HELPED TO GALVANIZE THE ANTI-NUCLEAR MOVEMENT IN THE UNITED STATES. THE ANTI-NUCLEAR MOVEMENT EMERGED AS A SOCIAL MOVEMENT AGAINST THE GLOBAL NUCLEAR ARMS RACE IN THE EARLY 1960S AT THE HEIGHT OF THE COLD WAR. • HIGH PROFILE PROTESTS IN RESPONSE TO THE EVENTS AT THREE MILE ISLAND TOOK PLACE AROUND THE COUNTRY, INCLUDING ONE IN NEW YORK CITY IN 1979 INVOLVING 200,000 PEOPLE. ANTI-NUCLEAR MOVEMENT
  11. 11. 3 MILE ISLAND FLASHBACK
  12. 12. THE ADVANTAGES OF NUCLEAR ENERGY NUCLEAR FUEL IS A VERY CONCENTRATED ENERGY SOURCE. NUCLEAR POWER PLANTS DO NOT PRODUCE AIR-POLLUTING GASES. NUCLEAR POWER PLANTS RELEASE LESS RADIOACTIVITY THAN COAL-FIRED POWER PLANTS DO, WHEN OPERATED PROPERLY. COUNTRIES WITH LIMITED FOSSIL-FUEL RESOURCES RELY HEAVILY ON NUCLEAR PLANTS TO SUPPLY ELECTRICITY.
  13. 13. • BUILDING AND MAINTAINING A SAFE REACTOR IS VERY EXPENSIVE. • THIS MAKES NUCLEAR PLANTS UNCOMPETITIVE WITH OTHER ENERGY SOURCES IN MANY COUNTRIES. • THE ACTUAL COST OF NEW NUCLEAR POWER PLANTS IS UNCERTAIN, SO IT IS DIFFICULT TO PREDICT WHETHER INVESTORS WILL BUILD NEW PLANTS IN THE UNITED STATES. WHY AREN’T WE USING MORE NUCLEAR ENERGY?
  14. 14. STORING WASTE oTHE GREATEST DISADVANTAGE OF NUCLEAR POWER IS THE DIFFICULTY IN FINDING A SAFE PLACE TO STORE NUCLEAR WASTE. oTHE FISSION PRODUCTS PRODUCED CAN REMAIN DANGEROUSLY RADIOACTIVE FOR THOUSANDS OF YEARS. oSTORAGE SITES FOR NUCLEAR WASTES MUST BE LOCATED IN AREAS THAT ARE GEOLOGICALLY STABLE FOR TENS OF THOUSANDS OF YEARS. oSCIENTISTS ARE RESEARCHING WAYS TO RECYCLE THE RADIOACTIVE ELEMENTS IN NUCLEAR FUEL.
  15. 15. SAFETY CONCERNS THE ROOT CAUSE REVEALED TO THE TMI ACCIDENT AS IDENTIFIED IN KEMENY REPORT, (THE REACTOR SAFETY COMMISSION IN 1979) ARE: • INSTRUMENTATION MALFUNCTION STUCK OPEN VALVE WITH NO INDICATION IN THE CONTROL ROOM. • INACCURATE PROBABILISTIC RISK ASSESSMENT FOR THE RELIEF VALVES. • NEGLECT OF LESSONS LEARNED FROM OTHER SIMILAR NUCLEAR POWER PLANT INCIDENTS.
  16. 16. SAFETY CONCERNS IN ADDITION TO THAT, THE LACK OF SAFETY CULTURE AMONG THE REGULATORS, SITE MANAGEMENT, AND TECHNICAL EXPERTS BY THE NEGLECTING LESSON LEARNED FROM OTHER NUCLEAR PLANT INCIDENTS TO BE INCORPORATED INTO THE PLANT DESIGN LED TO THAT ACCIDENT. THE OPERATOR REACTION TO THE FAULTY INSTRUMENT WAS ANOTHER INDICATION OF ABSENCE OF THE HUMAN RELIABILITY ASSESSMENT DURING THE PRE-OPERATIONAL STAGE. FORTUNATELY, ONLY A SMALL AMOUNT OF RADIOACTIVE GAS ESCAPED. SINCE THAT ACCIDENT, THE U.S. NUCLEAR REGULATORY COMMISSION HAS PROVIDED NUMEROUS SAFETY IMPROVEMENTS TO NUCLEAR PLANTS.
  17. 17. 3 MILE ISLAND LESSON Training reforms are among the most significant outcomes of the TMI-2accident. Training became centred on protecting a plant's cooling capacity, whatever the triggering problem might be. At TMI-2, the operators turned to abook of procedures to pick those that seemed to fit the event. Now operators are taken through aset of "yes-no" questions to ensure, first, that the reactor's fuel core remainscovered. Training hasgone well beyond button- pushing. Communications and teamwork, emphasizing effective interaction among crew members, are now part of TMI's training curriculum. Closetohalf of the operators' training is in a full-scale electronic simulator of the TMI control room. The$18 million simulator permits operators to learn and be tested on all kinds of accidentscenarios. Disciplines in training, operations andevent reporting that grew from the lessonsof the TMI-2 accident have made the nuclear power industry demonstrably safer and more reliable. Thosetrends have been both promoted and tracked by the Institute for Nuclear Power Operations (INPO). Onthe reliability front, the median capability factor for nuclear plants - the percentage of maximum energy that aplant is capable of generating - increasedfrom 62.7 percent in 1980 toalmost 90 percent in 2000. (The goal for the year 2000 was 87 percent.)
  18. 18. 3 MILE ISLAND LESSON Applying the accident's lessons produced important, continuing improvement inthe performance of all nuclear powerplants. Theaccident fostered better understanding of fuel melting, including improbability of a "China Syndrome" meltdown breaching the reactor vesseland the containment structure. Public confidence in nuclear energy, particularly in USA, declined sharply following the Three Mile Island accident. It was amajor causeof the decline in nuclear construction through the 1980sand1990s. Thesafety provisions include aseries of physical barriers between the radioactive reactor core and the environment, the provision of multiple safety systems, each with backup and designed to accommodate human error. Safety systems account for about one quarter of the capital cost of such reactors. Aswell asthe physical aspects of safety, there are institutional aspectswhich are no lessimportant. Thebarriers in atypical plant are: the fuel is in the form of solid ceramic (UO2)pellets, and radioactive fission products remain largely bound inside these pellets as the fuel is burned. Thepellets are packed inside sealed zirconium alloy tubes to form fuel rods. All this, in turn, is enclosed inside arobust reinforced concrete containment structure with walls at least one metre thick. This amounts to three significant barriers around the fuel, which itself is stable up to very high temperatures.
  19. 19. COMMON SAFETY CULTURE THE COMMON SAFETY CULTURE THEME THAT CAN BE CONCLUDED FROM THE THREE MOST PROMINENT NPP(FCT) ACCIDENTS ARE: • A MINDSET OF THE MANAGEMENT THAT IGNORE SEVERE ACCIDENTS POSSIBILITY. • A FAILURE TO MAKE EFFECTIVE DESIGN MAKING BASE ON USE OF OPERATIONAL EXPERIENCE LESSONS LEARNED. • INEFFECTIVE SAFETY AND RISK ASSESSMENTS. • POOR SYSTEMATICAL RESPONSE TO SEVERE ACCIDENT. • INEFFECTIVE TRAINING. • FAILURE TO PREDICT AND MANAGE PLANT BEHAVIOR UNDER ABNORMAL CONDITIONS. • LACK OF A QUESTIONING ATTITUDE, AND • DEFICIENT WORK PROCESSES
  20. 20. NEED OF USING SAFETY CULTURE SAFETY CULTURE IS PROVEN TO BE THE ONLY RESORT TO ENHANCE THE SAFETY PERFORMANCE IN ANY COMPLEX TECHNOLOGICAL SYSTEMS SUCH AS NPPS.  THE SAFETY CULTURE STARTS RIGHT AT THE BEGINNING OF THE PROJECT PROPOSAL. ALL THE SEVERE NUCLEAR POWER PLANT ACCIDENTS RESULTED FROM DEFICIENCIES OF THEIR SAFETY CULTURE.  IT IS MERELY IMPORTANT FOR THE NEWCOMERS TO GIVE THE SAFETY CULTURE AND NAMELY THE HUMAN AND ORGANIZATIONAL FACTORS ENOUGH ATTENTION DURING THE PLANNING PHASE TO AVOID FUTURE ACCIDENTS.
  21. 21. THE FUTURE OF NUCLEAR POWER ONE POSSIBLE FUTURE ENERGY SOURCE IS NUCLEAR FUSION. NUCLEAR FUSION IS THE COMBINATION OF THE NUCLEI OF SMALL ATOMS TO FORM A LARGER NUCLEUS. FUSION RELEASES TREMENDOUS AMOUNTS OF ENERGY. IT IS POTENTIALLY A SAFER ENERGY SOURCE THAN NUCLEAR FISSION IS BECAUSE IT CREATES LESS DANGEROUS RADIOACTIVE BYPRODUCTS.
  22. 22. THE FUTURE OF NUCLEAR POWER •ALTHOUGH THE POTENTIAL FOR NUCLEAR FUSION IS GREAT, SO IS THE TECHNICAL DIFFICULTY OF ACHIEVING THAT POTENTIAL. •THE TECHNICAL PROBLEMS ARE SO COMPLEX THAT BUILDING A NUCLEAR FUSION PLANT MAY TAKE DECADES OR MAY NEVER HAPPEN. •POTENTIAL FUTURE FISSION NUCLEAR POWER TECHNOLOGIES INCLUDE LIGHT WATER REACTORS OR HIGH TEMPERATUREGAS REACTORS.
  23. 23. REFERENCES  http://www.world-nuclear.org/info/inf36.html  http://en.wikipedia.org/wiki/Three_Mile_Island_accident  https://www.history.com/topics/1970s/three-mile-island

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It is a case study about Three Mile Island nuclear power plant accident which happened on 1979 in Pennsylvania(USA)

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