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THE THREE MILE ISLAND ELECTRIC GENRATOR MISHAP

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laura villanueva

on 18 May 2011

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Transcript of THE THREE MILE ISLAND ELECTRIC GENRATOR MISHAP

Timeline of Events Occurring During the Three Mile Island Disaster 00:00:00 Pumps feeding water to the secondary loop shut down.
This was the first of two independent system failures that led to the near meltdown of the Three Mile Island Nuclear Reactor 00:00:01 Alarm sounds within the TMI control room.
At the time this alarm is disregarded by the operators. 00:00:02 Water pressure and temperature in the reactor core rise.
The failure of the secondary loop pump has stopped the transfer of heat from the Primary Loop to the secondary loop. The rise in temperature and pressure is considered to be part of the normal plant operations, and hence ignored. 00:00:03 Pressure Relief valve (PORV) automatically opens
When the pressure of steam in the reactor core rises above safe limits, the pressure relief valve is designed to automatically open, releasing the excess steam to a containment tank. 00:00:04 Backup pumps for the secondary loop water system automatically turn on.
Four seconds into the accident the secondary loop water pumps are automatically turned on. This is indicated to the operators by the presence of lights on the control panel. The operators are not aware that the pumps have been disconnected and are not functioning. 00:00:09 Boron and Silver control rods are lowered into the reactor. PORV light goes out, indicating valve is closed.
Lowering of the control rods into the reactor core slows down the rate of the reaction. The effect of which is also a reduction in the heat produced by the reactor. When the PORV light goes out the operators incorrectly assume that the valve is closed. In reality the valve is not only open but is also releasing steam and water from the core. This is now a LOCA (Loss of Coolant Accident) 00:02:00 Emergency Injection Water (EIW) is automatically activated.
The EIW is a safety device that causes water to flow into the reactor core. It is designed to ensure that when there is a LOCA the water in the core remains at a safe level. In the past the EIW system has turned itself on when there has been no leak so the operators are not unduly concerned by this. 00:04:30 Operators observe that the water level in the Primary System is rising while the pressure is decreasing.
When they observe that the water level in the core is rising the operators shut off the EIW system. 00:04:30 Water level in the core still appears to be rising.
In actuality the water level in the core is dropping and turning off the EIW increases the amount of steam being produced by the reactor core. The combination of steam and water is still being released through the PORV. 00:08:00 Operator notices that the valves for the secondary loop backup pumps are off.
8 minutes into the accident the closed valve is noticed by an operator. Once he turns the valves back on the Secondary Water loop is functioning correctly. 00:45:00 Water level in primary loop continues to drop.
At this point in the accident the operators still do not suspect a LOCA. The instrument checking the radiation has not registered an alarm, and the gauges in the control room are wrongly indicating that the water level is up. 01:20:00 Primary loop pumps start to shake violently.
Steam produced by the lack of cooling water in the core passes through the primary loop pumps and causes them to shake. Assuming they are not functioning correctly the operators turn off two of the four pumps 01:20:00 Remaining two pumps in the primary loop turn off.
The automatic shut down of the two remaining pumps in the primary loop causes the water within the nuclear core to stop circulating. This in turn causes the heated core to convert more water into steam, further reducing the transfer of heat away from the core 02:15:00 Water level drops below the top of the core.
Once the top of the core is exposed the steam is converted to super heated steam. This reacts with the control rods and produces hydrogen and other radioactive gases 02:15:00 Hydrogen gas is released through PORV.
Since the Pilot Operated Relief Valve is still in the open position it allows the hydrogen gas produced to be released along with the steam. 02:20:00 Operator from next shift arrives and closes PORV backup valve.
02:20:30 Operators receive first indication that the radiation levels are up.
02:45:00 Radiation alarm sounds and a site emergency is declared.
At this point half the core is uncovered and the radiation level of the water in the primary loop is 350 times its normal level. 03:00:00 Due to higher radiation levels a General Emergency is declared.
There is still confusion as to whether the core is uncovered or not. There are some that feel the temperature readings may be erroneous. 07:30:00 Operators pump water into the primary loop and open the PORV backup valve to lower the pressure. 09:00:00 Hydrogen within the containment structure explodes.
The explosion is recorded by the instruments in the control room. It is dismissed as just being a spike caused by an electrical malfunction. The sound of the explosion heard is thought by some to be a ventilator damper 15:00:00 Primary loop pumps are turned on.
By now a large portion of the core has melted and there is still hydrogen present in the primary loop. Water from the primary loop pumps is circulated and the core temperature is finally brought under control THE THREE MILE ISLAND ELECTRIC GENERATOR MISHAP The most serious nuclear reactor accident to date in the United States occurred at 4 a.m. on March 28, 1979, at the Three Mile Island nuclear power plant outside Middletown, Pennsylvania. Radiological Health Effects?
The Three Mile Island accident caused concerns about the possibility of radiation-induced health effects, principally cancer, in the area surrounding the plant. Because of those concerns, the Pennsylvania Department of Health for 18 years maintained a registry of more than 30,000 people who lived within five miles of Three Mile 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.

Indeed, more than a dozen major, independent health studies of the accident showed no evidence of any abnormal number of cancers around TMI years after the accident. The only detectable effect was psychological stress during and shortly after the accident. The studies found that the radiation releases during the accident were minimal, well below any levels that have been associated with health effects from radiation exposure. The average radiation dose to people living within 10 miles of the plant was 0.08 millisieverts, with no more than 1 millisievert to any single individual. The level of 0.08 mSv is about equal to a chest X-ray, and 1 mSv is about a third of the average background level of radiation received by U.S. residents in a year.

In June 1996, 17 years after the TMI-2 accident, Harrisburg U.S. District Court Judge Sylvia Rambo dismissed a class action lawsuit alleging that the accident caused health effects. The plaintiffs have appealed Judge Rambo's ruling. The appeal is before the U.S. Third Circuit Court of Appeals. However, in making her decision, Judge Rambo cited: Timeline December 31, 1978:
Unit 2 of Metropolitan Edison Company’s nuclear generating plant at Three Mile Island (TMI) on the Susquehanna River March 28, 1979 Day 1:
4:00 AM: Due to equipment failure and operator error, a partial nuclear core meltdown of the TMI’s Unit 2 reactor. March 28, 1979 Day 1:
4:00 AM: Due to equipment failure and operator error, a partial nuclear core meltdown of the TMI’s Unit 2 reactor March 29, Day 2:
Plant officials were still attempting to fully assess the damage to the plant March 30, Day 3:
A "bubble" in the reactor vessel that led to some venting of radioactive material and garbled communications March 31, Day 4:
A false rumor that a "bubble" that had formed in the reactor potentially could explode April 1, Day 5:
With television news in tow, President Jimmy Carter and Governor Richard Thornburgh visited the control room of the plant April 6, Day 10:
Operators having regained control of the plant, Governor Thornburgh lifted the evacuation advisory and declared the Three Mile Island "crisis had passed." The cleanup would take years. October 25, 1979:
The Nuclear Regulatory Commission recommended the maximum fine permitted under law for Metropolitan Edison’s violations that contributed to the accident. Ocotber 30, 1979:
The Presidential Commission (Kemeny Commission) issued its report 1980:
For their coverage of the Three Mile Island accident, the staff of the Philadelphia Inquirer was awarded the Pulitzer Prize June/July 1980:
In preparation for entry into the reactor building venting of radioactive gasses proceeded over an eleven day period July 23, 1980:
The first person since the partial reactor core meltdown entered the TMI-2 reactor building May 18, 1982:
Central Pennsylvania voters in three counties voted to oppose the restart of Three Mile Island Unit 1 January 1991-August. 1993:
Processing of 2.23 million gallons of accident-generated water was completed http://www.threemileisland.org/virtual_museum/index.html Local journalists, of course, followed events at the Three Mile Island plant from Wednesday on, with an increasing sense of urgency as the reactor situation failed to be resolved. Reporters for various media (newspaper, television, radio) converged on Harrisburg and Middletown by the weekend, creating the need for periodic press conferences, which were scheduled and effective after the arrival of Harold Denton, a reactor specialist from the Nuclear Regulatory Commission. Most of those reporting on the accident had to, first, learn for themselves the basics of nuclear energy production and, second, educate the public on that, radiation and the potential outcomes of the emergency. Within hours, both journalists and local residents had learned a whole new vocabulary and conversed knowingly about core over-heating, melt-downs, and rems.

Those who reflected on the media’s roll in the emergency afterward suggested that local media did a fine job without becoming alarmist. Central Pennsylvanians felt that national and international media organizations, however, sensationalized the accident. Governor Thornburgh's Twentieth Anniversary Address, given at Dickinson College, provides at least one view of the role the media played in the emergency. Other viewpoints can be heard and read in the interviews available in the Resource Center. The media The accident at the plant occurred 12 days after the release of the movie The China Syndrome. It featured Jane Fonda as a news anchor at a California television station. In the film, a major nuclear plant crisis takes place while Fonda's character and her cameraman (Michael Douglas) are at the plant producing a series on nuclear power. She proceeds to raise awareness of how unsafe the plant is. Coincidentally, there is a scene in which Fonda's character speaks with a nuclear safety expert, who says that a meltdown could render an area "the size of Pennsylvania permanently uninhabitable." Also, the fictional near-accident in the movie stems from plant operators overestimating the amount of water within the core.

After the release of the film, Fonda began lobbying against nuclear power; she was the only actor in the film to do so. In an attempt to counter her efforts, the nuclear physicist Edward Teller, "father of the hydrogen bomb" and long-time government science adviser, personally lobbied in favor of nuclear power The China Syndrome Emergency declared

At 6:56 am, a plant supervisor declared a site emergency, and less than 30 minutes later station manager Gary Miller announced a general emergency, defined as having the "potential for serious radiological consequences" to the general public Metropolitan Edison notified the Pennsylvania Emergency Management Agency (PEMA), which in turn contacted state and local agencies, governor Richard L. Thornburgh and lieutenant governor William Scranton III, to whom Thornburgh assigned responsibility for collecting and reporting on information about the accident.[23] The uncertainty of operators at the plant was reflected in fragmentary, ambiguous, or contradictory statements made by Met Ed to government agencies and to the press, particularly about the possibility and severity of off-site radiation releases. Scranton held a press conference in which he was reassuring, yet confusing, about this possibility, stating that though there had been a "small release of radiation comprehension check
when did the three mile island accident happen?
what cause the accident to happen?
what group protest against nuclear power plants?
according to the video who were told to stay away?
what was the invissible thing, that humans around the area were scared of? Activism and legal actions

Anti-nuclear protest at Harrisburg in 1979, following the Three Mile Island Accident.The TMI accident enhanced the credibility of anti-nuclear groups, who had predicted an acciden. and triggered protests around the world

Members of the American public, concerned about the release of radioactive gas from the TMI accident, staged numerous anti-nuclear demonstrations across the country in the following months. The largest demonstration was held in New York City in September 1979 and involved 200,000 people, with speeches given by Jane Fonda and Ralph Nader. The New York rally was held in conjunction with a series of nightly “No Nukes” concerts given at Madison Square Garden from September 19–23 by Musicians United for Safe Energy. In the previous May, an estimated 65,000 people—including California Governor Jerry Brown—attended a march and rally against nuclear power in Washington, D.C.

In 1981, citizens' groups succeeded in a class action suit against TMI, winning $25 million in an out-of-court settlement. Part of this money was used to found the TMI Public Health Fund. In 1983, a federal grand jury indicted Metropolitan Edison on criminal charges for the falsification of safety test results prior to the accident Under a plea-bargaining agreement, Met Ed pleaded guilty to one count of falsifying records and no contest to six other charges, four of which were dropped, and agreed to pay a $45,000 fine and set up a $1 million account to help with emergency planning in the area surrounding the plant.

According to Eric Epstein, chair of Three Mile Island Alert, the TMI plant operator and its insurers paid at least $82 million in publicly documented compensation to residents for "loss of business revenue, evacuation expenses and health claims". Also according to Harvey Wasserman, hundreds of out-of-court settlements have been reached with alleged victims of the fallout, with a total of $15m paid out to parents of children born with birth defects. However, a class action lawsuit alleging that the accident caused detrimental health effects was rejected by Harrisburg U.S. District Court Judge Sylvia Rambo. The appeal of the decision in front of U.S. Third Circuit Court of Appeals also failed Three Mile Island Nuclear Generating Station (TMI) is a civilian nuclear power plant (NPP) located on Three Mile Island in the Susquehanna River, south of Harrisburg, Pennsylvania. It has two separate units, known as TMI-1 and TMI-2. The plant is widely known for having been the site of the most significant accident in United States commercial nuclear energy, on March 28, 1979, when TMI-2 suffered a partial meltdown. http://abcnews.go.com/video/playerIndex?id=9625032 Timeline of Events Occurring During the Three Mile Island Disaster 00:00:00 Pumps feeding water to the secondary loop shut down.
This was the first of two independent system failures that led to the near meltdown of the Three Mile Island Nuclear Reactor. 00:00:01 Alarm sounds within the TMI control room.
At the time this alarm is disregarded by the operators 00:00:02 Water pressure and temperature in the reactor core rise.
The failure of the secondary loop pump has stopped the transfer of heat from the Primary Loop to the secondary loop. The rise in temperature and pressure is considered to be part of the normal plant operations, and hence ignored 00:00:03 Pressure Relief valve (PORV) automatically opens
When the pressure of steam in the reactor core rises above safe limits, the pressure relief valve is designed to automatically open, releasing the excess steam to a containment tank 00:00:04 Backup pumps for the secondary loop water system automatically turn on.
Four seconds into the accident the secondary loop water pumps are automatically turned on. This is indicated to the operators by the presence of lights on the control panel. The operators are not aware that the pumps have been disconnected and are not functioning. 00:00:09 Boron and Silver control rods are lowered into the reactor. PORV light goes out, indicating valve is closed.
Lowering of the control rods into the reactor core slows down the rate of the reaction. The effect of which is also a reduction in the heat produced by the reactor. When the PORV light goes out the operators incorrectly assume that the valve is closed. In reality the valve is not only open but is also releasing steam and water from the core. This is now a LOCA (Loss of Coolant Accident)

00:02:00 Emergency Injection Water (EIW) is automatically activated.
The EIW is a safety device that causes water to flow into the reactor core. It is designed to ensure that when there is a LOCA the water in the core remains at a safe level. In the past the EIW system has turned itself on when there has been no leak so the operators are not unduly concerned by this.

00:04:30 Operators observe that the water level in the Primary System is rising while the pressure is decreasing.
When they observe that the water level in the core is rising the operators shut off the EIW system.

00:04:30 Water level in the core still appears to be rising.
In actuality the water level in the core is dropping and turning off the EIW increases the amount of steam being produced by the reactor core. The combination of steam and water is still being released through the PORV. 00:08:00 Operator notices that the valves for the secondary loop backup pumps are off.
8 minutes into the accident the closed valve is noticed by an operator. Once he turns the valves back on the Secondary Water loop is functioning correctly.

00:45:00 Water level in primary loop continues to drop.
At this point in the accident the operators still do not suspect a LOCA. The instrument checking the radiation has not registered an alarm, and the gauges in the control room are wrongly indicating that the water level is up.

01:20:00 Primary loop pumps start to shake violently.
Steam produced by the lack of cooling water in the core passes through the primary loop pumps and causes them to shake. Assuming they are not functioning correctly the operators turn off two of the four pumps 01:20:00Remaining two pumps in the primary loop turn off.
The automatic shut down of the two remaining pumps in the primary loop causes the water within the nuclear core to stop circulating. This in turn causes the heated core to convert more water into steam, further reducing the transfer of heat away from the core.

02:15:00 Water level drops below the top of the core.
Once the top of the core is exposed the steam is converted to super heated steam. This reacts with the control rods and produces hydrogen and other radioactive gases 02:15:00 Hydrogen gas is released through PORV.
Since the Pilot Operated Relief Valve is still in the open position it allows the hydrogen gas produced to be released along with the steam.

02:20:00 Operator from next shift arrives and closes PORV backup valve.
02:20:30 Operators receive first indication that the radiation levels are up.
02:45:00 Radiation alarm sounds and a site emergency is declared.
At this point half the core is uncovered and the radiation level of the water in the primary loop is 350 times its normal level. 03:00:00 Due to higher radiation levels a General Emergency is declared.
There is still confusion as to whether the core is uncovered or not. There are some that feel the temperature readings may be erroneous.

07:30:00 Operators pump water into the primary loop and open the PORV backup valve to lower the pressure.
09:00:00 Hydrogen within the containment structure explodes.
The explosion is recorded by the instruments in the control room. It is dismissed as just being a spike caused by an electrical malfunction. The sound of the explosion heard is thought by some to be a ventilator damper. 15:00:00 Primary loop pumps are turned on.
By now a large portion of the core has melted and there is still hydrogen present in the primary loop. Water from the primary loop pumps is circulated and the core temperature is finally brought under control.
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