OMAHA, Neb. (AP) — The Fort Calhoun nuclear power plant has been shut down for repairs roughly a month after a planned outage for maintenance and refueling. The Omaha Public Power District shut down the nuclear plant Monday after a water leak was discovered in one of Fort Calhoun’s four reactor coolant pumps after a seal failed.

The utility says the coolant water that leaked was contained inside the plant and treated. A spokeswoman says Nuclear Regulatory Commission inspectors are monitoring the repairs. Fort Calhoun sits along the Missouri River about 20 miles north of Omaha.

OPPD says the length of this outage will be determined by the repairs. If needed, the utility will buy electricity from other sources to maintain service. OPPD has more than 360,000 customers in 13 counties in southeast Nebraska.