BRACEVILLE, Ill. (Aug. 2, 2009) - Operators at Braidwood Generating Station Unit 2 early Sunday terminated an "unusual event" that had been declared Thursday evening at the nuclear power plant.
The Unit 2 reactor, one of two at the plant, had been shut down since about 9 p.m. Thursday when power coming into the plant was lost because of a transformer issue. The unusual event officially ended at approximately 12:30 a.m. Sunday after plant personnel completed inspections and work to restore electrical service. Unit 2 remained shut down Sunday morning. Unit 1 remained at full power.
As part of the plant shutdown, systems were depressurized and steam was released into the atmosphere, creating a loud noise. Such releases are typical of plant shutdowns when there is a disruption to incoming power and are allowed under the station's operating license, which is regulated by the Nuclear Regulatory Commission. The steam release, which went up about 100 feet from the release valves and dispersed into the atmosphere, contained expected levels of tritium ranging from 11,500 to 38,000 picocuries per liter of water. The amount released was less than .1 percent of all airborne radionuclide releases through normal plant operations over the course of a year.
"We appreciate the patience of our neighbors during the initial outage in which plant noise may have been loud and startling," said Braidwood Station Site Vice President Bryan Hanson. "It's also important that people realize that this kind of steam venting is part of the plant design and poses no environmental, health or safety impact to workers or to the public."
An unusual event is the lowest of four emergency classifications as defined by the Nuclear Regulatory Commission.
Braidwood Generating Station is approximately 60 miles southwest of Chicago.