OMAHA, Neb. (AP) — The troubled Fort Calhoun nuclear power plant in Nebraska is improving, but regulators said Tuesday that significant work remains ahead as the utility works to address previous deficiencies and structural problems discovered last year.

Omaha Public Power District CEO Gary Gates said the utility is strengthening its oversight of the plant, and Exelon — the company OPPD hired four months ago to run Fort Calhoun — is improving the safety culture at the idle plant while overseeing the repairs.