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 Three."
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.