A berm holding the flooded Missouri River back from a Nebraska nuclear power station collapsed early Sunday, but federal regulators said they were monitoring the situation and there was no danger. 
 
 The Fort Calhoun Nuclear Station shut down in early April for refueling, and there is no water inside the plant, the U.S. Nuclear Regulatory Commission said. Also, the river is not expected to rise higher than the level the plant was designed to handle. NRC spokesman Victor Dricks said the plant remains safe. 
 
 The federal commission had inspectors at the plant 20 miles (32 kilometers) north of Omaha when the 2,000-foot (610-meter) berm collapsed about 1:30 a.m. Sunday. Water surrounded the auxiliary and containment buildings at the plant, it said in a statement. 
 
 The Omaha Public Power District has said the complex will not be reactivated until the flooding subsides. Its spokesman, Jeff Hanson, said the berm wasn't critical to protecting the plant but a crew will look at whether it can be patched. 
 
 "That was an additional layer of protection we put in," Hanson said. 
 
 The berm's collapse didn't affect the reactor shutdown cooling or the spent fuel pool cooling, but the power supply was cut after water surrounded the main electrical transformers, the NRC said. Emergency generators powered the plant until an off-site power supply was connected Sunday afternoon, according to OPPD. 
 
 NRC Chairman Gregory Jaczko said the loss of the berm at Fort Calhoun nuclear plant doesn't threaten the safety of the plant. 
 
 "There are other structures and systems in place that can ensure they will continue operating safely," Jaczko said. 
 
 Jaczko will tour the Fort Calhoun plant Monday. His visit was scheduled last week. On Sunday, he toured Nebraska's other nuclear power plant, which sits along the Missouri River near Brownville. Cooper nuclear power plant is about 75 miles (120 kilometers) south of Omaha and run by the Nebraska Public Power District. 
 
 Jaczko said he can't predict what the river will do this summer but that NPPD and OPPD seem to be taking appropriate steps to defend against flooding. 
 
 Jaczko spent much of his tour of Cooper asking NPPD officials and the NRC's local inspectors questions about the plant and this year's flooding. He said his visit was designed to gather information. 
 
 NPPD officials have been monitoring river levels closely during the flooding, and they have already brought in more than 5,000 tons of sand to build barricades protecting the Cooper plant, the onsite power substations and the plant's access roads. 
 
 Accessing critical parts of the plant requires visitors to use ladders or steel stairs to climb over sandbag barriers both outside and inside the doors. When the Jaczko saw one of Cooper's two back-up diesel generators, he had to climb over three different sandbag barriers to get there. 
 
 The Cooper plant remains dry because it sits at an elevation above the river level. The base of Cooper and its storage area for used nuclear fuel is 903 feet (275.23 meters) above sea level while on Sunday the river was just above 899 feet. 
 
 Cooper would be shut down if the river rose to 902 feet (274.93 meters) above sea level, but officials say that is unlikely. 
 
 "This plant is designed to deal with a flood much higher than we are seeing _ 906 feet," Jaczko said. 
 
 Both nuclear plants issued flooding alerts earlier this month, although they were routine as the river's rise has been expected. Cooper has been operating at full capacity. 
 
 Flooding remains a concern all along the Missouri because of massive amounts of water the U.S. Army Corps of Engineers has released from upstream reservoirs. The river is expected to rise as much as 7 feet (2 meters) above flood stage in much of Nebraska and Iowa and as much as 10 feet (3 meters) over flood stage in parts of Missouri. 
 
 The corps expects the river to remain high at least into August because of heavy spring rains in the upper Plains and substantial Rocky Mountain snowpack melting into the river basin. 
 
 ___ 
 
 Josh Funk Associated Press Writer Timberly Ross contributed to this report from Omaha and can be reached at http://twitter.com/timberlysross. ||||| The head of the Nuclear Regulatory Commission has been dispatched to a nuclear power plant in Fort Calhoun, Neb., where a berm collapsed Sunday, but the public is in no danger, officials said. 
 
 The breach allowed Missouri River flood waters to reach containment buildings and transformers and forcing the shutdown of electrical power. 
 
 Backup generators are cooling the nuclear material at the Fort Calhoun Nuclear Station. 
 
 The plant has not operated since April, and officials say there is no danger to the public. 
 
 Jeff Hanson, a spokesman for the Omaha Public Power District, told The Associated Press that the breached berm wasn't critical to protecting the plant, although a crew will look at whether it can be patched. 
 
 "That was an additional layer of protection we put in," Hanson said. 
 
 Nevertheless, federal inspectors are on the scene. 
 
 Meanwhile, there was no protecting thousands of homes in Minot, N.D., where flooding of the Souris River hit its peak today, flooding more than 4,000 homes, including Leslie Dull's. 
 
 "When you actually see your house," Dull said, "and you know it's not just your basement, it's your whole house, it's ... 
 
 "I'm sorry," she said, as she broke down crying. 
 
 There is some good news: The river in Minot peaked two feet lower than expected. But it is nearly 13 feet above flood stage and it is expected to stay near that level for days. 
 
 "It could be two to four to six weeks, or more, before the water actually goes back into its banks ... [and] before [residents] get to come and see their houses," Brig. Gen. Bill Seekins of the North Dakota National Guard told ABC News during a tour through the flooded areas. 
 
 Seekins described the scene as "almost apocalyptic." 
 
 Sgt. Dave Dodds of the North Dakota National Guard said heavy rains from Saturday will keep the river at its historic crest for longer than expected. 
 
 "Authorities were hoping for maybe a day or two before it started to recede, but you can add maybe an additional 24 hours onto that," Dodds said. 
 
 Minot Mayor Curt Zimbelman said the devastation may be even greater than expected. 
 
 "I think we're going to reach probably 4,500 [homes] before this is all done, where we've got a lot of water on these homes," Zimbelman said. 
 
 Randy Nelson and his wife just bought a camper, knowing their house is flooded. They are living in a shopping center parking lot, powerless to do anything but wait. 
 
 He said the hardest part is "patience ... not knowing where you are going to live. It's tough." 
 
 But there have been victories. ABC News watched Koni Aho race to build a berm around her restaurant down river from Minot. Twenty-four hours later there was still no water in the restaurant. 
 
 "I was bound and determined," she said. "I don't care. I said, 'It's just dirt. We can move it.'" 
 
 Forecasters said scattered storms were in today's forecast, but the worst part of the storm will likely to be south and east of the Souris River Basin. 
 
 Neighbors Helping Neighbors 
 
 Officials were building and re-enforcing levees in the towns of Sawyer and Velvenau in fear that all the water that has been coming through Minot will swamp the two towns. 
 
 As residents and officials brace for the worst, acts of generosity were seen throughout the community. 
 
 Garages were turned into storage units for flood victims and families and churches opened their doors to other displaced community members. 
 
 "For the rest of the country, that is kind of mind-boggling. But ... that's how we are in North Dakota," Sen. John Hoeven told the Associated Press. 
 
 Evangelical Lutheran pastor Mike Johnson said he was too preoccupied with helping other people that he wasn't sure about the condition of his belongings after being evacuated from the flood zone the previous week. 
 
 But Lutherans in a neighboring town stepped in and took care of his files and equipment in his office. 
 
 "They just showed up on Tuesday and carted stuff off for us," Johnson told the Associated Press. 
 
 ABC News' Gerard McNiff and the Associated Press contributed to this report.
– Floodwaters have poured over a berm surrounding a Nebraska nuclear power plant, forcing a shutdown of electricity used to control cooling systems. Emergency generators were used until an off-site power supply could be connected to the Fort Calhoun plant, and officials say there has been no danger to the public, reports ABC News. Federal authorities, including the head of the Nuclear Regulatory Commission, are on the scene. The berm was considered an "additional layer of protection" at the plant, and a work crew will attempt to patch it, said a spokesman for the Omaha Public Power District. The plant, near Brownville, has been closed for refueling since April, and the operation won't be restarted until the floodwaters recede, according to AP. Nebraska's other nuclear power plant, some 75 miles south of Omaha, was threatened by flooding earlier this month and will be shut down if floodwaters exceed a specific level. Federal officials are continuing to monitor the situation. The Fort Calhoun berm breach was the latest trouble in flooding of the Missouri River that has inundated some 4,500 homes. It could be up to six weeks before the river falls back to its pre-flood stage.