This is why Japan should have chosen the Canadian CANDU reactor design
over the USA GE design:
Mark 1 Nuclear Reactor Design Caused GE Scientist To Quit In Protest
Damaged Japanese Nuclear Plant Has Five Mark 1 Reactors
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.
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 1's.
"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.''
Bridenbaugh told ABC News that he believes the design flaws that
prompted his resignation from GE were eventually addressed at the
Fukushima Daiichi plant. Bridenbaugh said GE agreed to a series of
retrofits at Mark 1 reactors around the globe. He compared the retooling
to the bolstering of highway bridges in California to better withstand
"Like with seismic refitting, they went back and re-analyzed the loads
the structures might receive and beefed up the ability of the
containment to handle greater loads," he said.
When asked if that was sufficient, he paused. "What I would say is, the
Mark 1 is still a little more susceptible to an accident that would
result in a loss of containment."
ABC News asked GE for more detail about how the company responded to
critiques of its Mark 1 design. GE spokesman Michael Tetuan said in an
email that, over the past 40 years, the company has made several
modifications to its Mark 1 reactors in the U.S., including installing
"quenchers" and fortifying the steel structures "to accommodate the
loads that were generated." He said that GE's responses to modifications
ordered by the Nuclear Regulatory Commission were also shared with the
Japanese nuclear industry.
Bridenbaugh told ABC News that he is watching the events in Japan with a
mix of anxiety and deep reflection. Many years have passed since he and
fellow GE colleagues Gregory C Minor and Richard B. Hubbard publicly
resigned, joined the anti-nuclear movement, and became known as the "GE
Undoubtedly, he said, the containment structures at that Fukushima
Daiichi plant are facing significant amounts of pressure -- and testing
the very questions he was studying on paper more than three decades
earlier. While he knew then that the Mark 1 had design limits, he said,
no one knows now whether those limits will be surpassed.
- posted 9 years ago