March 21, 2011 -- General Electric has released a paper defending the performance of its nuclear reactor in Japan, and said the "station blackout" caused by the massive 9.0 earthquake and tsunami went beyond anything they had contemplated when the plant's containment system was designed four decades ago.
"Coincident long-term loss of both on-site and off-site power for an extended period of time is a beyond-design-basis event for the primary containment on any operating nuclear power plant," says the paper, which was produced by the Nuclear Energy Institute, an industry trade group.
GE emailed the 21-page paper to reporters over the weekend after a series of unflattering reports about the history of the Mark 1 reactor that was in use at the Fukushima Daiichi plant in Northeast Japan. Questions have persisted for decades about the ability of the Mark 1 to handle the immense pressures that would result if the reactor lost cooling power. The design is being put to the ultimate test in Japan, where a series of explosions and the partial melting of radioactive fuel has brought the country to the brink of a nuclear disaster. Five of the six reactors at the Fukushima Daiichi plant are Mark 1s.
CLICK HERE to read the paper.
In the 1970s, concerns about the design of the Mark 1 led three top GE scientists to resign in protest and join an anti-nuclear campaign to publicize the dangers of nuclear power. One of those scientists, Dale G. Bridenbaugh, told ABC News that even after a series of modifications aimed at strengthening the Mark 1, that particular design was still less suited to handle the pressures of an emergency similar to the one in Japan.
"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 said. "The impact loads the containment would receive by this very rapid release of energy could tear the containment apart and create an uncontrolled release."
Mark 1 Reactors 'Appear To Have Held Pressure'
It may still be weeks before anyone knows how the Mark 1 containment system performed in the face of this challenge, but the NEI paper says the Mark 1 containment vessels "appeared to have held pressure to well above the design pressure."
The manner in which the reactors have responded, the company says, "in general agree[s] with severe accident management studies performed in the 1980s and early 1990s."
Most of the paper is highly technical, but it describes how the company developed a plan to upgrade and strengthen the containment systems once it had officially been warned by the Nuclear Regulatory Commission that it needed to be stronger.
The paper does not say whether the Japanese plants were subject to the same retrofits.
GE spokesman Michael Tetuan said, "We understand that all of the BWR Mark I containment units at Fukushima Daiichi ... implemented modifications in accordance with Japanese regulatory requirements."