In the wake of the Japanese nuclear emergency spawned by last week’s devastating earthquake and tsunami, questions are being raised about the design of a General Electric nuclear reactor known as the Mark 1. Nuclear opponents have criticized the Mark 1 as inferior to other reactor designs, USA Today reported, saying that its containment systems are smaller and more vulnerable to rupturing under high pressure. The Mark 1 design was used at five of the six nuclear reactors located at Japan’s troubled Fukushima Daiichi plant.
According to an ABC News report, 35 years ago, three nuclear scientists went so far as to resign from their positions at General Electric because of their concerns over the Mark 1 nuclear reactor design.
“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,” Dale G. 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.”
However, Bridenbaugh went on to tell ABC News that he believes the design flaws that prompted his resignation from General Electric were eventually addressed at Japan’s Fukushima Daiichi plant, and added that GE agreed to a series of retrofits at Mark 1 reactors around the globe. How effective such retrofitting might have been is questionable though, with Bridenbaugh admitting that “the Mark 1 is still a little more susceptible to an accident that would result in a loss of containment.”
Over the years, others have also expressed concerns over the Mark 1 nuclear reactor design. According to the USA Today report, U.S. Atomic Energy Commission official Stephen Hanauer said in a 1972 memo that the type of system used in the Mark 1 was vulnerable and should be discontinued. According to ABC News, in 1986, Harold Denton, then the director of the Nuclear Regulatory Commission’s Office of Nuclear Reactor Regulation, raised doubts, saying he did not “have the same warm feeling about GE containment that I do about the larger dry containments.”
General Electric, for its part, insists the Mark 1 nuclear reactor design is safe. In a statement to USA Today, the company said Mark 1 is an industry “workhorse” with a proven safety record for more than 40 years.
According to The New York Times, 23 reactors at 16 locations in the U.S. use the Mark 1 design, including the Oyster Creek plant in central New Jersey, the Dresden plant near Chicago and the Monticello plant near Minneapolis. Those reactors have undergone a variety of modifications since the initial concerns were raised, the Times said.