- Unheeded warning of the day: The Mark 1 Nuclear Reactor’s containment system, produced by General Electric in the 1960s, has been the subject of pointed safety concerns for nearly forty years. Stephen Hanauer, then an official with the Atomic Energy Commission, wrote in 1972 that the Mark 1’s pressure systems posed an unacceptable risk of hydrogen explosion, and should be discontinued. You probably know where this is going- the Fukushima Plant in Japan uses the Mark 1, as do twenty-three American reactors. A critical difference between these and the more highly regarded pressurized water reactors? The Mark 1’s containment vessel is “physically less robust.” So, because apparently this needs saying, don’t skimp on nuclear reactor containment. source