A nuclear power plant in New Jersey declared an alert Monday from mega-storm Sandy as water passed a minimum level but no safety concerns were reported, the US nuclear regulator said.

The Oyster Creek nuclear power plant, in Ocean County just north of the resort of Atlantic City, was already on a scheduled outage as the massive storm made landfall nearby on the Atlantic Coast.

The Nuclear Regulatory Commission said the plant sounded an alert -- one notch above the lowest of the watchdog's four categories for action levels -- as the facility recorded a designated high mark for water inside.

"Water level is rising in the intake structure due to a combination of a rising tide, wind direction and storm surge," the commission said in a statement.

"It is anticipated water levels will begin to abate within the next several hours," it said.

The regulator said that all plants in the storm's way were in safe condition and that inspectors were working to verify independently that operators underwent proper procedures.

Concerns about nuclear power spiked in March 2011 in Japan's massive earthquake and tsunami caused a meltdown at the Fukushima plant, triggering clouds of radiation and forcing tens of thousands of people to flee their homes -- perhaps permanently.

Sandy has ravaged the eastern United States, plunging hundreds of thousands into darkness and flooding the subway and the usually bustling streets underneath New York's iconic skyline.