NRC probes radiation at TMI

Posted on Mon., Nov. 23, 2009

By Jan Hefler

Philadelphia Inquirer Staff Writer

Investigators with the U.S. Nuclear Regulatory Commission yesterday found that a minimal amount of radiation had leaked inside a reactor at the Three Mile Island nuclear power plant Saturday afternoon but did not pose any health threats to the public.

However, some state and local officials, including Gov. Rendell, said they were upset that notifications were not made in a timely way to authorities.

Diane Screnci, NRC spokesperson, said that the leak had "no effect on public health or safety" because it was confined to a reactor building at the central Pennsylvania plant, about 10 miles south of Harrisburg. She also said about 20 of the 151 workers inside the building either inhaled radiation or touched contaminated surfaces, but said the amount was not harmful.


"The exposure was less than 1 percent of the NRC regulatory limit for workers," Screnci said.


Exelon Nuclear spokesman Ralph DeSantis said the incident occurred while the plant was shut down for refueling and the replacement of a massive steam generator. While workers cut the pipes from the old generator to remove it, a small amount of radiation was released, DeSantis said.


"A monitor with a very low threshold went off and we immediately took action," DeSantis said. "Nobody was hurt and no equipment was damaged."


DeSantis said investigators were still trying to narrow down the cause. "Workers were cutting pipes, or welding, or using an industrial-size vacuum when it happened. There was a fair amount of activity going on in the building at the time," he said.


Workers were checked on-site for radiation exposure and none required any further treatment, DeSantis said.


Tests showed the contamination was confined to surfaces and to the equipment inside the building.


The unit has been shut down since Oct. 26 for the refurbishing. DeSantis said that workers began decontaminating the reactor building yesterday and are expected to resume work soon.


Steve Letavic, manager of Londonderry Township, where the plant is located, said that Exelon notified him and township emergency officials very quickly after the incident. He said town officials were assured there was no threat to the public. A meeting with Exelon representatives is planned for today.


But Robert Reid, mayor of Middletown, the borough adjacent to Londonderry, said five hours passed before he learned of the release. "I would have liked to been told 15 minutes after the incident took place," he said, noting that people called him to ask what was going on.


Gov. Rendell feels the notification could have been more timely but at this point is not calling for a formal investigation, said his spokesman Gary Tuma. "The governor has concerns and would like to know what happened and why it took so long" to contact some local and state authorities, said Tuma.


The governor is writing a letter to Exelon, saying a five-hour delay is not appropriate, Tuma said. "They have no legal obligation to notify us, because the level of the radiation didn't meet that threshold; it would have been appropriate to notify us sooner."


Eric Epstein, with TMI Alert, a nuclear power watchdog group, said his organization wanted to make sure workers do not return "until the root cause has been isolated and defeated." "The sheer size of people who were being exposed in one swoop makes this a significant event," Epstein said.


A partial meltdown occurred in Three Mile Island's Unit 2 reactor on March 28, 1979. It was the nation's most serious nuclear event, though no one was killed. A simple malfunction in a valve drained water from the Unit 2 reactor. That led to a release of radiation - how much remains a matter of contention - a potentially explosive hydrogen bubble, and the partial meltdown of the radioactive core.


Contact staff writer Jan Hefler at 856-779-3224 or

Staff Writer Amy Worden contributed to this article.