WARRENVILLE — Elevated levels of radioactive tritium have been found in water leaked at two more Exelon Corp. nuclear power plants, the utility announced Wednesday.
The leaks occurred at the Dresden Generating Station in Grundy County and Byron Nuclear Generating Station, about 25 miles southwest of Rockford.
Exelon also operates the nuclear power plant in Clinton.
Exelon recently has come under fire in Will County, where the state's attorney's office began an investigation last week into why the company did not disclose until recently a series of tritium-containing wastewater leaks between 1996 to 2003 at its Braidwood Generating Station, about 60 miles southwest of Chicago.
Tests last week confirmed the Dresden plant leak, Exelon said in a statement, which was discovered within a few weeks after it began. Tests also were conducted last week at the Byron station. Exelon officials said neither leak poses a health or safety threat.
Tritium is a radioactive substance commonly found in groundwater, but is more concentrated in water used in nuclear reactors. Studies have shown long-term exposure through drinking or bathing can lead to cancer and birth defects.
Levels of tritium about 25 times higher than the safe drinking water limit set by the U.S. Environmental Protection Agency were found in a test well near the center of the Dresden property, officials said. Surrounding test wells found levels at or lower than the EPA limit, apparently indicating a localized concentration.
At Byron, water with tritium levels about four times the EPA limit was found standing inside concrete vaults in the ground where several valves are located. Environmental samplings and engineering work is being done to determine if tritium has leaked into the ground outside the vaults.
Exelon said it plans this year to assess all its nuclear power generating facilities in three states to minimize the risk of inadvertent tritium discharges.
"We realize that inadvertent releases are unacceptable and we are committed to eliminating them," Exelon Nuclear chief operating officer Charles Pardee said in the statement.
Exelon has 17 nuclear power units at six sites in Illinois, three in Pennsylvania and one in New Jersey.