"Five years before the crucial emergency vents at the Fukushima Daiichi nuclear plant were disabled by an accident they were supposed to help handle, engineers at a reactor in Minnesota warned American regulators about that very problem.
Anthony Sarrack, one of the two engineers, notified staff members at the Nuclear Regulatory Commission that the design of venting systems was seriously flawed at his reactor and others in the United States similar to the ones in Japan. He later left the industry in frustration because managers and regulators did not agree.
Mr. Sarrack said that the vents, which are supposed to relieve pressure at crippled plants and keep containment structures intact, should not be dependent on electric power and workers’ ability to operate critical valves because power might be cut in an emergency and workers might be incapacitated. Part of the reason the venting system in Japan failed — allowing disastrous hydrogen explosions — is that power to the plant was knocked out by a tsunami that followed a major earthquake."