OMAHA, Neb (Reuters) - About 120 Fort Calhoun Nuclear Station employees moved back into the flooded plant's administration building on Monday.

The plant, which was idled April 9 for routine refueling and maintenance, remained shut down this summer after Missouri River floodwater spread across the riverside site near Blair, Nebraska, in June.

The river has dropped about two feet since its crest, allowing workers to dismantle elevated walkways and parking lots to reopen at the 478-megawatt plant.

The river was more than four feet above flood stage Monday at Blair. It is expected to be back in its banks in September.

Omaha Public Power District, which operates the plant, has sent plans for restarting the reactor to the federal Nuclear Regulatory Commission.

(Reporting by David Hendee; Editing by James Kelleher and Jerry Norton)