By Roberta Rampton and Ayesha Rascoe
WASHINGTON (Reuters) - Democratic lawmakers warned a Pennsylvania nuclear power plant would be at risk of a meltdown in the case of a severe emergency, though top U.S. nuclear officials said the chances of such an event occurring were not likely.
The Peach Bottom nuclear plant, owned by utilities Exelon and Public Service Enterprise Group Inc's PSEG Power, has the same kind of reactor design as the failed Fukushima Daiichi plant, which Japanese authorities are still trying to bring under control since a March 11 earthquake and tsunami.
In worst-case computer modeling exercises done by the U.S. nuclear regulator, the Peach Bottom plant came "dangerously close to core damage," Democrats on a House Energy and Commerce subcommittee said at the hearing on whether changes are needed to make U.S. plants safer in the wake of the Japanese disaster.
Twenty-three other U.S. nuclear power plants use the same reactor design. The study was done on only two of the 104 U.S. nuclear plants.
"This is a frightening scenario for the American people, for sure," said Diana DeGette of Colorado, who noted the plant is less than 40 miles from the city of Baltimore, Maryland.
A top official from the Nuclear Regulatory Commission said that the computer modeling exercise ignored the probability of worst-case power loss events happening.
"You have to first consider how likely this is to occur," said Martin Virgilio, the deputy executive director for the NRC's reactor and preparedness programs.
"It doesn't give me concern," Virgilio said, responding to questions from DeGette about the results of the modeling exercise.
NRC-FUKUSHIMA VESSEL NOT BREACHED
At the hearing, Edward Markey, a prominent critic of the nuclear industry, said the NRC had warned that Fukushima's No. 2 reactor had likely melted through its vessel, a key part of the containment for radioactive materials.
But Virgilio said that had not happened yet, based on information from NRC staff in Tokyo.
"We get situation reports from our team multiple times during the day and so far we do not believe the core has actually breached" the vessel, Virgilio told reporters.
"We believe there is significant fuel damage at all three of the reactors, significant fuel damage in all four of the spent fuel pools. We don't believe at this point in time that that core has left the vessel," he said.
Virgilio also said there were differences in the designs of the reactors in the United States and Japan, both boiling water reactors designed by GE.
"We've done quite a bit to modify that design over the life of the facilities as a result of operating experience. We don't know for sure, but there are some evidence that the Japanese designs did not keep pace, they did not make the same modifications that we've made," he said.
The regulator is currently reviewing the 104 plants in the United States to see whether any changes are needed after assessing the Japan disaster.
GOP: FOCUS ON FACTS
Republican lawmakers said the review of U.S. plants needs to focus on facts.
"We should not confuse what is happening in Japan with our own preparedness and assume they are one and the same," said Cliff Stearns, a Florida Republican.
"If changes need to be made to our nuclear safety plants and regulations, then so be it. But, unfortunately sometimes in the past we've had a history of moving a little too quickly and letting our regulations get ahead of the facts," said Michael Burgess of Texas.
(Reporting by Roberta Rampton and Ayesha Rascoe; Editing by Lisa Shumaker)