Unfortunately, the berm at Fort Calhoun has now broken. As the New York Times notes:
Fort Calhoun, took two steps backward on Sunday. In the pre-dawn hours, a piece of heavy equipment nicked a temporary rubber berm, 8 feet high and 2,000 feet long, and it deflated. And water there began to approach the switchyard, where grid power enters the complex, so operators started up their diesel generators.
Similarly, CNN reports:
A water-filled berm protecting a nuclear power plant in Nebraska from rising floodwaters collapsed Sunday, according to a spokesman, who said the plant remains secure.
Some sort of machinery came in contact with the berm, puncturing it and causing the berm to deflate, said Mike Jones, a spokesman for the Omaha Public Power District (OPPD), which owns the Fort Calhoun plant…
The 6 to 12 inches of rainfall in the upper Missouri basin in the past few weeks is nearly a normal year’s worth, and runoff from the mountain snowpack is 140% of normal, according to forecasters.