According to the Associated Press
the leak of radioactive dust occurred when maintenance workers were cutting a pipe at the plant near Middletown, Pennsylvania, which was the scene in 1979 of the worst nuclear accident in U.S. history.
The incident in March 1979 involved a partial meltdown of the second reactor on the site in Pennsylvania. That second reactor has not been in operation for the three decades since the accident took place, no workers at the site or members of the general public were injured as a result of the meltdown, and as Xinhua News Agency
reports no nuclear power plants have been built in the U.S. during the intervening years.
Once the operating license for the Unit 1 reactor, where Saturday's radiation leak occurred, expires both it and the redundant Unit 2 reactor will be decommissioned
confirms that the Unit 1 reactor is owned and operated by Exelon Corporation, which monitors the Unit 2 reactor for its owner FirstEnergy. Exelon Corporation has its headquarters in Chicago and FirstEnergy is based in Akron, Ohio.
As for the leak at Unit 1 on Saturday - the reactor has been shut down since late October to allow for maintenance work, refueling and steam generator replacement - there was no risk to the health of the public as the contamination did not spread beyond the building housing the reactor, the building was subsequently decontaminated, and the 12 workers who did receive low doses of radiation were decontaminated also.
The U.S. Nuclear Regulatory Commission (NRC) has confirmed that no worker received a dose of radiation that came close to exceeding the annual federal regulatory limit. One worker was exposed to 16 millirem
of radiation but the annual limit for workers is 2,000 millirem. A chest X-ray will typically expose a person to 6 millirem of radiation notes CNN
A spokesman for the Three Mile Island plant explained that radiation can be cleaned off external surfaces, safety suits for example, and any person inhaling radiation can expect to see it leave their body naturally within the space of two to three days.
Speaking on behalf of the NRC Diane Screnci said that when a nuclear plant is being refueled or its generators are being replaced small radiation leaks can be expected.
There were initially plans for the maintenance work at Three Mile Island to recommence on Sunday but that was not the case as the investigation in to the exact cause of the radiation leak continues, although the Associated Press
quotes plant spokesman Ralph DeSantis as saying:
We are back to work and back to normal right now
One person concerned that workers are returning to the plant before the cause of the leak has been identified is Eric Epstein, chairman of the watchdog group TMI-Alert. Established in 1977 TMI-Alert states on its website
that it is "a non-profit citizens' organization dedicated to the promotion of safe-energy alternatives to nuclear power and is especially critical of the Three Mile Island nuclear plant".
With coal-fired power plants criticized for the harm they cause to the environment nuclear reactors are seen by some as less harmful sources of power and the lifting of the moratorium on the construction of nuclear plants is a possibility. However, irrespective of the size of the radioactive leak in Pennsylvania on Saturday, there may now be fresh concerns about the safety of nuclear power plants.