By Mike DeNardo

SALEM, N.J. (CBS) – The Salem Unit-One nuclear plant in South Jersey remains shut down, after radioactive water leaked in a containment building Thursday night.

Salem’s Unit-One nuclear plant was shut down around 7:30 p.m., when radioactive water started to leak, says Nuclear Regulatory Commission spokeswoman Diane Screnci:

“They had a valve on one of the systems within the containment. And that valve was leaking, and it reached what are called their technical specification limits, and caused them to begin a shutdown.”

The leak was measured at four gallons a minute — above the one gallon per minute threshold to force a shutdown.

Screnci says the spill of radioactive water was confined in a containment unit and posed no threat to PSEG, Nuclear workers or the public. She says NRC inspectors are on hand to monitor the efforts to fix the leak and give the green light to restart when it’s safe.