An aerial view of the Fort Calhoun Nuclear Power Plant in eastern Nebraska, surrounded by Missouri River flood waters June 24, 2011. Credit: Reuters/Lane HickenbottomThe Omaha World-Herald reports that the "Aqua dam" protecting vital areas at the Fort Calhoun nuclear power plant against the historic flood on the Missouri River 20 miles north of Nebraska's largest city has collapsed. The 8 foot tall, berm shaped rubber wall, filled with water, has failed. It had been looked to as a major last line of defense to protect vital "systems, structures, and components" at the atomic reactors and its auxiliary buildings -- including the high-level radioactive waste storage pool. But even worse flooding is expected in the future. Meanwhile, as reported by Reuters, the Chairman of the U.S. Nuclear Regulatory Commission, Greg Jaczko, was scheduled to visit the Cooper atomic reactor south of Omaha today, followed by a helicopter survey of flooding on the Missouri and countermeasures upstream of the two Nebraska nuclear power plants. Jaczko is scheduled to visit Fort Calhoun on Monday. As the Nebraska Watchdog reports, just last year NRC busted Omaha Public Power District for vulnerability to flooding on the Missouri River; this likely has enhanced response capability in the current crisis, but as flood waters continue to rise, and with the failure of the Ft. Calhoun anti-flood rubber berm, the question remains, did it do so well enough?