Groundwater Contamination
There are two underground aquifers within the first 230 feet (70.1 m) below the power station: the upper aquifer is known as the Galena-Platteville Aquifer and the lower aquifer is known as the St. Peter Sandstone Aquifer. The two bodies of water are separated by a layer of shale and thus not connected.
In February 2006, Exelon reported elevated tritium levels in the groundwater beneath the site. Tritium levels were elevated in two of six test wells, according to an Exelon release in February which noted that tritium concentrations of 86,000 pCi/L were detected in standing water in underground concrete vaults along the plant's blowdown line. The company iterated that the levels posed no risk to public or employee safety. The report coincided with ongoing tritium concerns at the Exelon-owned Braidwood Nuclear Generating Station near Braceville, Illinois. In September, elevated tritium levels were found at Byron in three monitoring wells adjacent to vacuum breaker vaults along the blowdown line. Two of the areas with elevated tritium were found in the shallow portions of the Galena-Platteville Aquifer, while the third location contained elevated tritium levels at the bottom of the same aquifer. None of the September levels exceeded the 20,000 pCi/L U.S. Environmental Protection Agency drinking water standard.
On April 12, 2006 the Illinois Environmental Protection Agency (IEPA) issued a violation notice to Exelon concerning Byron Nuclear Generating Station. The notice cited the company for violations of state environmental laws related to the "impairment of resource groundwater", discharging waste-containing contaminants from areas other than the permitted points, and violations of other requirements of the plant's discharge permit.
Due to the tritium contamination at Byron, Braidwood and Dresden nuclear power plants in Illinois, the state government passed a law requiring power plants to report the release of radioactive contaminants into the soil, surface water or ground water to the state within 24 hours. Before the law was passed, companies operating nuclear plants were only required to report such releases to the federal NRC. The law was introduced by Illinois State Representative Careen Gordon and State Senator Gary Dahl, and was signed by Illinois Governor Rod Blagojevich on June 11, 2006 and became effective immediately upon his signature. The state government only found out about the tritium releases at the Exelon-owned plants after local officials near the Braidwood plant informed them. Following that revelation, other information about spills at Braidwood, Byron, and Dresden came to light. The state of Illinois contended that it was not informed of the leaks by Exelon in a timely manner. The law also required all Illinois nuclear power plants to submit to quarterly inspections by the IEPA and the Illinois Emergency Management Agency.
Read more about this topic: Byron Nuclear Generating Station