CORRECTED – UPDATE 2-Democrats raise concern about nuclear plant

 (Corrects to show reactors were designed by GE, not
Westinghouse in paragraph 13)
 * Democrats: Simulation concerning for Peach Bottom plant
 * Worst-case disaster would bring plant close to meltdown
 * NRC official: Simulation is for highly improbable events
 * NRC says Fukushima reactor core has not breached vessel
 * Some signs Japan reactor design did not keep pace-NRC
 By Roberta Rampton and Ayesha Rascoe
 WASHINGTON, April 6 (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
(EXC.N: Quote, Profile, Research) and Public Service Enterprise Group Inc's (PEG.N: Quote, Profile, Research) 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. [ID:nL3E7F62A5]
 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
 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.
 Factbox of US plants similar to Fukushima [ID:nN24140384]
 US nuclear regulator meshes physics, politics
 "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 (64 km) from the city of Baltimore,
 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
 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 (GE.N: Quote, Profile, Research).
 "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.
 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)

CORRECTED - UPDATE 2-Democrats raise concern about nuclear plant