Earthquake prompts inspections at Fermi 2 nuclear power plant; NRC virtual meeting planned
The earthquake felt throughout Metro Detroit on Friday did not trigger seismic alarms at the Fermi 2 nuclear plant in Monroe County, but it did prompt safety inspections, according to DTE Energy.
The 3.2-magnitude earthquake was recorded Friday evening south-southeast of Detroit Beach near Monroe by the U.S. Geological Survey. Officials said the plant was unaffected by the tremor and is operating normally.
The Nuclear Regulatory Commission will host a previously scheduled virtual meeting on the plant's performance at 5:30 p.m. Thursday. Those who wish to participate must register online.
The earthquake, rare for Michigan, occurred at 6:55 p.m just off the shoreline of Sterling State Park, according to USGS and about two miles from the nuclear reactor that went online in 1988.
The depth was determined to be 9.2 km, or about 5.71 miles. The USGS initially reported the quake as reaching 3.4 magnitude.
In a statement Saturday, DTE Energy spokesman Stephen Tait said the seismic activity did not compromise the safety of the plant.
"There were no alarms or indicators at the plant associated with the seismic activity. Our seismic monitors are designed to alert operators if the certain seismic activity level is reached; that did not occur during this event due to the low-level activity.
"The plant is in a safe, stable condition and we are at 100 percent power. All plant systems are operating normally and as expected."
A magnitude 3.2 quake is considered minor and generally does not cause damage, said Dongdong Yao, a postdoctoral research fellow affiliated with the University of Michigan who has studied seismic activity in the region.
Downriver residents and those as far away as Bowling Green, Ohio, reported feeling the quake. The intensity rippled throughout Downriver, including Trenton, La Salle, Grosse Ile, south to northern Ohio, as far north as Waterford Township and in Macomb County. However, it left the Fermi plant unfazed, officials said.
Tait said following the seismic activity, the plant followed pre-planned inspections and procedures to ensure safety. His statement did not specifically indicate if those inspections were complete or found any irregularities.
"The plant informed the Nuclear Regulatory Commission (NRC) of those procedures taking place. No further reporting to the NRC is required," Tait said.
Ben van der Pluijm, a University of Michigan professor in the Department of Earth and Environmental Sciences, said reactivations — when dormant faults become active again — are common, but are not typically large enough in Michigan to create damage.
"Nuclear power plants are engineered to withstand earthquakes greater than M3 (and plane attacks). I am not sure about the exact seismic specs of Fermi, but it is in a low-risk seismic location," van der Pluijm said.
The plant was operating at 100% Friday and Saturday after earlier this month completing a refueling operation that was prolonged by the coronavirus pandemic, according to reports from the Nuclear Regulatory Commission.
The NRC had not posted an event notification report regarding the earthquake by Saturday evening.
Friday's quake came more than a year after the agency recorded a temblor with a magnitude of 4.0 in Lake Erie, just off the shoreline of northeast Ohio, in June 2019. That was considered an "intra-plate" earthquake, USGS officials said at the time.
In April 2018, a magnitude 3.6 quake originated near Amherstburg, Ontario, across the Detroit River, some 15.5 miles south of Detroit. It was felt at least 40 miles away in parts of Downriver and Dearborn.
The USGS website says that most earthquakes in North America east of the Rockies "occur as faulting within bedrock, usually miles deep."
"Few earthquakes east of the Rockies, however, have been definitely linked to mapped geologic faults, in contrast to the situation at plate boundaries such as California's San Andreas fault system, where scientists can commonly use geologic evidence to identify a fault that has produced a large earthquake and that is likely to produce large future earthquakes."