ST. PAUL -- No radiation leaked and there were no injuries this morning when 522 gallons of chlorine bleach leaked out of a broken pipe at the Prairie Island nuclear power plant near Red Wing, Minn.

"This is a non-radioactive event," state Emergency Management Director Kris Eide said.

Eide and Dennis Koehl of Xcel Energy said the public faces no threat, even though this morning's alert is believed to be the highest-ever emergency level declared at either of Minnesota's nuclear power facilities.

Koehl said Xcel is investigating why the PVC pipe sprung a leak, releasing bleach into an area surrounded by cement berms. He said the bleach did not get into the Mississippi River or anywhere else behind the contained area.

Xcel workers were pumping the bleach into another container today and Koehl said he expects the clean-up to be complete by 6 p.m.

Workers discovered the leak at 3:53 a.m., and Xcel immediately reported the incident to state officials, as required by law. The state opened its Emergency Operations Center in St. Paul, staffed by up to 60 workers from state departments and some private organizations.

The leak occurred in what is called a "screen house," a facility where water pumped from the Mississippi River is treated so it can be used to cool two nuclear reactors. Koehl said bleach is used to kill bacteria in the water.

The pipe that leaked is connected to one of two bleach tanks, and Koehl said the second tank can be used to keep both reactors functioning. The nuclear facilities were not affected, he added, and power was not interrupted.

Koehl said air near the leak of what formally is known as sodium hypochloride was safe, and Xcel workers did not need breathing apparatus to work around the bleach.

Eide said the public was in no danger. Minnesota and Wisconsin officials said the public does not need to take any action.

"We are not asking for any kind of protective action," Eide said.

While Prescott and Ellsworth, Wis., schools delayed their start today, Eide said that was up to individual school district superintendents, not on the recommendations of state officials.

In the Minnesota Emergency Operations Center, the atmosphere was calm with few people working on the spill incident. However, officials said, the center was staffed with a variety of state and private agencies just in case something was needed.

Goodhue County, Minn., and Pierce County, Wis., emergency operations centers were activated. The Mississippi separates Minnesota and Wisconsin.

The alert issued after the leak was discovered was the second-lowest emergency notification category for nuclear plants. Xcel officials said they did not think that either the Prairie Island or Monticello plants ever have declared an alert or higher emergency.

State and Xcel officials annually train for such emergencies.

The Prairie Island Plant, next to an American Indian community of the same name, is 28 miles southeast of St. Paul and six miles northwest of Red Wing. The two reactors in the plant produce enough electricity to power a million homes.