Incident Chronology at TMI from NRC: 1979-2012

March 28, 1979, 4:00 a.m. - Beginning of the Three Mile Island (TMI) Unit-2 loss-of-coolant, core melt accident. The plant came within 30 minutes of a full meltdown. The reactor vessel was destroyed, and large amounts of unmonitored radiation was released directly into the community.

March 28, 1979, 4:30 p.m. - Press conference of Lt. Governor William Scranton:
This is an update on the incident at Three-Mile Island Nuclear Power Plant today. This situation is more complex than the company first led us to believe. We are taking more tests. And at this point, we believe there is still no danger to public health. Metropolitan Edison has given you and us conflicting information. We just concluded a meeting with company officials and hope this briefing will clear up most of your questions. There has been a release of radioactivity into the environment. The magnitude of this release is still being determined, but there is no evidence yet that it has resulted in the presence of dangerous levels. The company has informed us that from about 11 a.m. until about 1:30 p.m., Three-Mile Island discharged into the air, steam that contained detectable amounts of radiation.

March 30, 1979 - Governor Richard Thornburgh recommended an evacuation for preschool children and pregnant women living within five miles of the plant. Out of a target population of 5,000, over 140,000 Central Pennsylvanians fled the area. Schools in the area closed...
The U.S. House of Representatives committee examining reporting information during the accident concluded:
The record indicates that in reporting to State and federal officials on March 28, 1979, TMI managers did not communicate information in their possession that they understood to be related to the severity of the situation. The lack of such information prevented State and federal officials from accurately assessing the condition of the plant. In addition, the record indicates that TMI managers presented State and federal officials misleading statements (i.e. statements that were inaccurate and incomplete) that conveyed the impression the accident was substantially less severe and the situation more under control than what the managers themselves believed and what was in fact the case.

May 22, 1979 - Former control room operator Harold W. Hartman, Jr. tells Nuclear Regulatory Commission (NRC) investigators that Metropolitan Edison- General Public Utilities (GPU) had been falsifying primary-coolant, leak rate data for months prior to the accident. At least two members of management were aware of the practice. NRC investigators do not follow-up or report the allegations to the Commission (See February 29, 1984, for first-ever criminal conviction of a nuclear utility for violating the Atomic Energy Act.)

June 22, 1979 - Governor Richard Thornburgh wrote to the NRC, expressing his "deeply felt responsibility for both the physical and psychological well being of the citizens of Pennsylvania." Thornburgh stated his "strong opposition to any plans to reactivate Unit -1 until a number of very serious issues are resolved."

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