Three Mile Island Restarts after Scram

Thursday, May 14, 2015 @ 04:05 PM gHale

Three Mile Island nuclear plant reopened Monday, after a five-day unplanned shutdown that occurred when a control rod and steam bypass valve malfunctioned.

Last Wednesday, the nuclear plant in Dauphin County, PA, ended up manually shut down after a control rod that controls the nuclear fission process dropped. There are dozens of control rods in the reactor.

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During the shutdown, a main steam bypass valve closed even though it was supposed to open. That resulted in a release of steam to the atmosphere multiple times, heard by residents surrounding the plant.

TMI owner Exelon said no radiation detectable by monitors released.

The Nuclear Regulatory Commission (NRC) said two resident inspectors at TMI were continuing to monitor Exelon’s evaluation of the problem, the repairs made and the restart.

“In general, the shutdown was safely carried out,” said NRC spokesman Neil Sheehan.

A relief valve on the coolant side of the reactor that operated opposite of what its design called for contributed to the partial meltdown of the core at TMI in the infamous 1979 accident.

Exelon reported that TMI returned to full power Monday after electrical repairs to the control rod drive mechanism.

TMI generates enough electricity to power 800,000 homes.

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