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The cleanup of the damaged nuclear reactor system at Three Mile Island Unit 2 took nearly 12 years and cost approximately $973 million. The cleanup was uniquely challenging technically and radiologically. Plant surfaces had to be decontaminated. Water used and stored during the cleanup had to be processed. About 100 tons of damaged uranium fuel had to be removed from the reactor vessel — all without hazard to cleanup workers or the public.
After the March 28, 1979 event, a cleanup plan was developed and carried out safely and successfully by a team of more than 1,000 skilled workers.
The cleanup of the Unit 2 plant began in August 1979 with the first shipments of accident-generated low-level radiological waste to Richland, Wa. 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. The cleanup ended in December, 1993, when Unit 2 received a license from the Nuclear Regulatory Commission to enter Post Defueling Monitored Storage (PDMS).
Early in the cleanup, Unit 2 was completely severed from TMI Unit 1. TMI-2 today is in long-term monitored storage. No further use of the plant is anticipated. Ventilation and rainwater systems are monitored. Equipment necessary to keep the plant in safe long-term storage is maintained.
Removing the fuel from the TMI-2 reactor vessel was the heart of the cleanup. The damaged fuel remained underwater throughout the removal process. In October 1985 after nearly six years of preparations, workers standing on a platform 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, a program that was completed in April 1990.
TMI-2 cleanup operations produced more than 2.8 million gallons of cleanup-generated water that was processed, stored and ultimately evaporated safely from Unit 2. Evaporation began in January 1991 and was completed in August 1993.
In February 1991, the TMI-2 Cleanup Program was named by the National Society of Professional Engineers as one of the top engineering achievements in the United States completed during 1990.
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