Groundwater contamination
Radioluminescent 1.2 curie 4" x .2" tritium vials are tritium gas filled thin glass vials whose inner surfaces are coated with a phosphor. Tritium contamination has been a problem at the Byron plant.
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.[8]
In February 2006, Exelon reported elevated tritium levels in the groundwater beneath the site.[9] 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.[10] The company iterated that the levels posed no risk to public or employee safety.[10] The report coincided with ongoing tritium concerns at the Exelon-owned Braidwood Nuclear Generating Station near Braceville, Illinois.[9] 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.[8] None of the September levels exceeded the 20,000 pCi/L U.S. Environmental Protection Agency drinking water standard.[8]
On April 12, 2006 the Illinois Environmental Protection Agency (IEPA) issued a violation notice to Exelon concerning Byron Nuclear Generating Station.[11] 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.[11]
The water facility that brings water to and from the Byron Plant from the Rock River.
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.[12] 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.[12] 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.[12] The state of Illinois contended that it was not informed of the leaks by Exelon in a timely manner.[12] The law also required all Illinois nuclear power plants to submit to quarterly inspections by the IEPA and the Illinois Emergency Management Agency.[12]
Safety
A closer view of Byron Nuclear Generating Station, including both containment buildings, in August 2005
As of the second quarter of 2007, Byron Nuclear Generating Station scored in the "green" in every NRC inspection category but one. The NRC has four levels of inspection findings, the levels are color-coded and the colors equate with risk levels. Green inspection findings represent very low risk significance. Higher levels, from white, to yellow, to red, show increasing levels of risk. For any inspection findings greater than green, the NRC conducts follow-up inspections.[13] Unit One scored "green" in every category, while Unit Two scored "white," a step down from "green," on the inspection of the heat removal system.[14][15] The inspection covered several other significant areas, including unplanned scrams, the alert and notification system and the emergency AC power system.[14] From 2001–2005, no inspections of Byron Nuclear Generating Station found any condition that merited a greater than "green" designation, during the same time period inspection found 71[16] green conditions at the Byron plant.[17]
Byron, like most U.S. nuclear plants, has been the subject of various actions by the NRC. Escalated Enforcement Actions represent one type. From 1997–2007 the Byron plant has received five such actions, two of which resulted in a total of $150,000 in fines.[18] A $100,000 fine was issued on February 27, 1997 due to problems with excessive silt build up in two separate locations at the Byron facility; the NRC fined the plant $50,000 for each problem.[18][19] The NRC levied an additional $55,000 in fines in October 1997 when the plant failed technical specifications surveillance guidelines. Specifically, they violated rules that require the Emergency Core Cooling System (ECCS) pump casing and discharge piping high points be vented once every 31 days.[20] The potential safety consequence of the violation affiliated with the second fine was considered "low."[20] As of 2007, the last NRC Escalated Enforcement Action against the Bryon Station came in 2005 when an engineer deliberately falsified surveillance reports to show he had completed work that was incomplete, though the plant could have been fined up to $60,000 the NRC chose not to impose the fine.[18][21]
A small fire occurred at the plant on the morning of February 24, 2006.[22] The fire was confined to the Unit 1 Refueling Water Storage Tank (RWST) heater. Initial attempts to extinguish the fire were unsuccessful, following those attempts a breaker was opened and the heater was allowed to deenergize which extinguished the fire. Units 1 and 2 were operating at 100%, but neither reactor was shut down as a result of the fire.[22] As a result of the fire the plant declared an "unusual event," the least serious of the four categories of emergency declarations by the Nuclear Regulatory Commission.[23]
On January 30, 2012, the Byron Unit 2 was shutdown and depressurized after suffering a power outage affecting power generation at the unit. Steam was vented to prevent over-pressure of the reactor core, while the turbines remained offline. A small amount of radioactive tritium was released into the local environment during the initial venting procedure. [24] [25]
Source: http://en.wikipedia.org/wiki/Byron_Nuclear_Generating_Station
