By Aaron Clark
“We have stopped work inside the reactor building while we investigate the cause of the contamination,” Beth Archer, a company spokesman said in a telephone interview. “There was no contamination outside the reactor building and there was no threat to public health and safety.”
A monitor near a temporary opening cut into the containment building created to move the new steam generators inside “showed a slight increase in a reading and then returned to normal” Exelon said in a statement yesterday. The 786-megawatt unit has been shut since Oct. 26 for refueling and maintenance during which workers will replace the steam generation.
About 150 workers inside the containment building were sent home at about 4 p.m. yesterday after an airborne radiological alarm sounded. One worker received 16 millirem of exposure, which is below the U.S. Nuclear Regulatory Commission’s limits. Exelon’s “annual occupational dose limit” for nuclear workers is 2,000 millirem.
A millirem is a unit of measurement for a radiation dose. The average person is exposed to about 360 millirems a year from naturally occurring radiation, according to the American Nuclear Society.
The U.S. Nuclear Regulatory Commission has sent a radiation specialist and a regional manager to the power plant to “follow-up on yesterday’s incident” the commission said in an e-mailed statement today.
Unit 2 at Three Mile has been shut since 1979 following a partial core meltdown. It was the biggest nuclear accident in U.S. history.