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

2. 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.

3. •AN ISLAND LOCATED ON THE SUSQUEHANNA RIVER NEAR MIDDLETOWN
PENNSYLVANIA.
LOCATION
http://www.ki4u.com/three_mile_island.htm

4. 3 MILE ISLAND REACTOR

5. 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 ?

6. 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 ?

7. • 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

8. • 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

9. 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.

10. 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.

11. • 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

12. 3 MILE ISLAND FLASHBACK

13. 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.

14. • 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?

15. 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.

16. 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.

17. 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.

18. 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.)

19. 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.

20. 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

21. 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.

22. 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.

23. 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.

24. 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