The United States Nuclear Regulatory Commission (NRC) released a study last week which considered how different power loss scenarios at two U.S. based nuclear power plants would compromise reactor integrity. The two plants considered for the study are the Peach Bottom Atomic Power Station near Lancaster, PA and the Surry Power Station in Virginia. These two sites were selected according to the study because each one has a different reactor design which is similar to designs in the other nuclear power stations throughout the nation. Peach Bottom uses a boiling water reactor (BWR) and the Surry station uses a pressurized water reactor (PWR).
According to the Nuclear Regulatory Commission “There are currently 104 licensed to operate nuclear power plants in the United States (69 PWRs and 35 BWRs), which generate about 20% of our nation's electrical use.”
The study, called the State-of-the-Art Reactor Consequence Analyses (SOARCA), considered several accident scenarios which could trigger reactor damage including what it known as a Station Black Out (SBO) or total loss of power. One event that could trigger such a scenario from the study was an earthquake. The study concluded that if a prolonged loss of power occurred with no back up power generation capability, core damage could begin after one hour with reactor vessel failure at around 9 to 16 hours for a scenario involving the Peach Bottom plant. For the Surry, VA plant in the same power loss scenario, the times were doubled roughly to reach the same level of failure because the design of that reactor allows a longer time for on-site engineers to provide cooling water to the core.
NRC: The State-of-the-Art Reactor Consequence Analyses (SOARCA) project, conducted by the U.S. Nuclear Regulatory Commission (NRC), is a research effort to realistically estimate the outcomes of postulated severe accident scenarios that might cause a nuclear power plant to release radioactive material into the environment.
The importance of the study became even more critical following an April 2011 earthquake in Japan. The quake triggered a Tsunami which severed power to the Fukushima One Nuclear Power Plant. Three of the plants nuclear reactors melted due to prolonged loss of cooling water. The resulting failure spewed radiation over a large area surrounding the plant and forced the evacuation of thousands of residents.
Peach Bottom Atomic Power Station is operated by Exelon Generation Company. The study did not include acts of terror as a scenario because the study focused on accidental triggers. NRC officials have allowed a comment period on the study. According to a NRC press release this week:
The SOARCA team will meet with the public on Tuesday, Feb. 21 from 5 to 9 p.m. at the Surry County Courthouse, 45 School St. in Surry, Va. The team will also meet with the public on Wednesday, Feb. 22 from 5 to 9 p.m. at the Peach Bottom Inn, 6085 Delta Road in Delta, Pa. The team will present the project’s findings, answer questions and take comments on the draft report.
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