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Regional News
| Article published Thursday, June 20, 2002
Corrosion is seen as ‘serious
accident’
But no ruling yet by full
commission
By MICHAEL WOODS
BLADE SCIENCE
EDITOR
ROCKVILLE, Md. - The staff of the U.S. Nuclear
Regulatory Commission has termed the reactor corrosion at
FirstEnergy Corp.’s Davis-Besse Nuclear Power Station a "serious
accident," although the full commission has not decided on how to
categorize the incident, an official said yesterday.
Edwin M.
Hackett denied a report that an NRC panel already had concluded that
the incident carried only minor safety significance.
Mr.
Hackett, a leader of an NRC task force investigating the incident,
said no decision has been made in NRC’s significance determination
process. He made the comments during a task force meeting at NRC
headquarters here.
The NRC ranks seriousness of problems at
nuclear power plants on a color-coded scale. The scale ranges from
green for a finding of minor significance, through white and yellow
to red, for a finding of high safety significance.
In a
presentation at the task force meeting, David Lochbaum said he
learned that NRC already has made a green determination.
Mr.
Lochbaum, a nuclear safety engineer with the Union of Concerned
Scientists, said the finding usually implies that operators of a
nuclear power plant acted in an acceptable fashion.
The
Davis-Besse incident involved unprecedented rusting of the
protective steel vessel that keeps radiation safely inside the
reactor. A years-long leak of acidic water from inside the reactor
caused the corrosion.
Despite numerous red flags, the leak
went undetected until March, when plant workers discovered that it
had eaten a half-foot hole about the size of a football in the
carbon steel on the reactor head. Only a thin stainless steel liner
kept the radiation inside, preventing a possible
catastrophe.
The liner is NRC’s basis for the green
determination, Mr. Lochbaum said.
FirstEnergy and NRC staff
have calculated that the liner was strong enough to continue holding
back the more than 2,000 pounds per square inch of pressure inside
the reactor.
Mr. Lochbaum said the calculations are
irrelevant.
The liner, he argued, is not intended as a
pressure-tight safety system, and never has been tested as
such.
NRC staff gave the Davis-Besse incident a ranking of 3
on the International Nuclear Event Scale, developed by the
International Atomic Energy Agency. The scale runs from 0 (no safety
significance) to 7 (a major accident).
A 3 signifies a
"serious accident." The 1986 accident at the Chernobyl nuclear power
plant in the Ukraine got a 7.
Thomas Koshy, an NRC official
familiar with the ranking systems, said INES is based on different
considerations than the NRC’s own rating scale. He suggested it
would be possible for Davis-Besse to receive a rating different than
the INES rating.
A green finding, Mr. Lochbaum contended,
would severely damage NRC’s credibility.
He noted that
numerous agencies now investigating FirstEnergy - ranging from NRC’s
own criminal division to the U.S. Congress - suspect the company’s
performance was unacceptable.
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