Quake Causes Nuke Alert

Thursday, October 18, 2012 @ 02:10 PM gHale

An earthquake about 50 miles away from the Seabrook nuclear power plant Tuesday forced the facility to declare an unusual event, the lowest of four levels of emergency classifications.

The unusual event was the result of on-site ground motion resulting from the earthquake centered near Hollis, ME, said officials at the Nuclear Regulatory Commission (NRC).

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The earthquake struck Maine on Tuesday shortly after 7 p.m., according to the U.S. Geological Survey (USGS). It first reported as a 4.5 magnitude quake centered near Lake Arrowhead, but USGS revised the quake’s magnitude to 4.6 and finally down to 4.0.

The Seabrook plant is already down for a scheduled refueling and maintenance outage. Following procedures used when there is seismic activity affecting the plant, NextEra workers conducted initial walkdowns, i.e., visual inspections, and confirmed all key safety systems were functioning properly and that there was no significant structural damage. The company will subsequently gather more seismic data and perform more detailed inspections.

The NRC resident inspector assigned to Seabrook responded to the site to confirm the plant was stable and that there were no immediate safety issues. NRC inspectors will inspect key safety systems to confirm the company’s post-earthquake evaluations, including the more detailed reviews.

“This evening, by procedure, Seabrook Station declared an unusual event due to the seismic activity felt throughout the region,” NextEra Energy officials said in a statement.

“There has been no impact to the plant from the earthquake and our outage activities have not been affected in any way. We expect to exit from the unusual event shortly,” said NextEra, which owns the plant.

“By way of background, Seabrook is designed to withstand the strongest earthquake ever experienced in New England, and then some,” NextEra said.

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