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Home > The Blotter from Brian Ross

Fukushima: Mark 1 Nuclear Reactor Design Caused GE Scientist To Quit In
Protest

Damaged Japanese Nuclear Plant Has Five Mark 1 Reactors

127 comments

By MATTHEW MOSK

March 15, 2011

Thirty-five years ago, Dale G. Bridenbaugh and two of his colleagues at
General Electric resigned from their jobs after becoming increasingly convinced
that the nuclear reactor design they were reviewing -- the Mark 1 -- was so
flawed it could lead to a devastating accident.

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Questions persisted for decades about the ability of the Mark 1 to handle the
immense pressures that would result if the reactor lost cooling power, and today
that design is being put to the ultimate test in Japan. Five of the six reactors
at the Fukushima Daiichi plant, which has been wracked since Friday's earthquake
with explosions and radiation leaks, are Mark 1s.

"The problems we identified in 1975 were that, in doing the design of the
containment, they did not take into account the dynamic loads that could be
experienced with a loss of coolant," Bridenbaugh told ABC News in an interview.
"The impact loads the containment would receive by this very rapid release of
energy could tear the containment apart and create an uncontrolled release."

The situation on the ground at the Fukushima Daiichi plant is so fluid, and
the details of what is unfolding are so murky, that it may be days or even weeks
before anyone knows how the Mark 1 containment system performed in the face of a
devastating combination of natural disasters.

But the ability of the containment to withstand the events that have cascaded
from what nuclear experts call a "station blackout" -- where the loss of power
has crippled the reactor's cooling system -- will be a crucial question as
policy makers re-examine the safety issues that surround nuclear power, and
specifically the continued use of what is now one of the oldest types of nuclear
reactors still operating.

GE told ABC News the reactors have "a proven track record of performing
reliably and safely for more than 40 years" and "performed as designed," even
after the shock of a 9.0 earthquake.

Still, concerns about the Mark 1 design have resurfaced occasionally in the
years since Bridenbaugh came forward. In 1986, for instance, Harold Denton, then
the director of NRC's Office of Nuclear Reactor Regulation, spoke critically
about the design during an industry conference.

"I don't have the same warm feeling about GE containment that I do about the
larger dry containments,'' he said, according to a report at the time that was
referenced Tuesday in The Washington Post.

"There is a wide spectrum of ability to cope with severe accidents at GE
plants,'' Denton said. "And I urge you to think seriously about the ability to
cope with such an event if it occurred at your plant.''

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