On
March 28, 1979, America experienced its worst nuclear accident - a partial
meltdown of the reactor core at the Three Mile Island nuclear power plant near
Middletown, Pennsylvania. During the tension-packed week that followed, sketchy
reports and conflicting information led to panic, and more than one hundred
thousand residents, mostly children and pregnant women, fled the area.
·
Early on the morning of March 28, several water-coolant pumps failed on the second reactor at Three Mile Island (TMI-2), causing the reactor to overheat.·
The reactor shut itself down eight seconds later, but the core temperature continued to rise because valves controlling the emergency cooling water were stuck closed.·
Sixteen hours later, the core was finally flooded and its temperature brought under control.
By
this time, half of the core had melted, and part of it had disintegrated,
although it was years before scientists actually discovered that a
meltdown had occurred. TMI-2 had only been in operation for 90 days when
the accident occured.
·
On March 30, later known as "Black Friday," rumors circulated about an uncontrolled release of radiation from the plant and Pennsylvania's governor ordered the evacuation of children and pregnant women living within 5 miles of the plant. Later, it was learned that the release had been planned to ease pressure within the system.·
On April 2, 1979, five days after the meltdown, the crisis at Three Mile Island was officially declared to be over.·
Although TMI-2's containment held and only minimal radioactive material was released, the reactor was heavily contaminated. No one could enter the plant for two years.·
The TMI-2 reactor was eventually entombed in concrete and TMI-1 was restarted in 1986.Impact of the Three Mile Island Disaster
A combination of equipment failure, human error, and bad luck, the nuclear
accident at Three Mile Island stunned the nation and permanently changed the
nuclear industry in America. Even though it led to no immediate deaths or
injuries to plant workers or members of the nearby community, the TMI accident
had a devastating impact on the nuclear power industry - the Nuclear Regulatory
Commission has not reviewed an application to build a new nuclear power plant in
the United States since. It also brought about sweeping changes involving
emergency response planning, reactor operator training, human factors
engineering, radiation protection, and many other areas of nuclear power plant
operations.
Health Effects of Three Mile Island
Various studies on health effects, including a 2002 study conducted by the
University of Pittsburgh, have determined the average radiation dose to
individuals near Three Mile Island at the time of the meltdown was about 1
millirem - much less than the average, annual, natural background dose for
residents of the central Pennsylvania region. Twenty-five years later, there has
been no significant rise in cancer deaths among residents living near the Three
Mile Island site. A new analysis of health statistics in the region conducted by
the Radiation and Public Health Project has, however, found that death rates for
infants, children, and the elderly soared in the first two years after the Three
Mile Island accident in Dauphin and surrounding counties.
Three Mile Island Today
Today, the TMI-2 reactor is permanently shut down and defueled, with the reactor
coolant system drained, the radioactive water decontaminated and evaporated,
radioactive waste shipped off-site to an appropropriate disposal site, reactor
fuel and core debris shipped off-site to a Department of Energy facility, and
the remainder of the site being monitored. The owner says it will keep the
facility in long-term, monitored storage until the operating license for the
TMI-1 plant expires on April 1, 2014, at which time both plants will be
decommissioned.