When people in the southeastern part of York County hear a three-minute-long siren blast Wednesday morning and then another alarm Thursday, don't worry, according to the company that operates the Peach Bottom Atomic Power Station and Muddy Run Pumped Storage.

One of the nuclear plant's warning sirens is undergoing maintenance, after which, about 10 a.m., the siren will sound for three minutes so the company knows it still works, according to a release from Exelon Generation, which owns and operates the plant.

The nuclear power plant is at 1848 Lay Road in Peach Bottom Township, right on the Conowingo Reservoir in the Susquehanna River, but the siren being tested Wednesday is across the river in Lancaster County.

This is not part of the semi-annual test that the Delta-area plant is mandated to conduct. During that test, which is scheduled for June and December each year, the company tests its full alert system, which consists of 97 sirens scattered around a 10-mile radius surrounding the plant, according to the release.

If an emergency were to happen, those sirens are supposed to alert area residents to tune to an emergency alert broadcast station, where they'll be able to hear information from state officials. During Wednesday's test, the emergency broadcast system won't be activated.

Then on Thursday, the quarterly test for the Muddy Run hydroelectric facility's emergency warning system will occur about 10 a.m., according to a news release from Exelon, which also owns that facility.

According to a news release, a brief tone will sound, followed by the words “This is a test, this is a test.” The whole thing will take about two minutes.

The hydroelectric facility's warning system consists of six sets of loudspeakers mounted atop poles upstream and downstream from the facility, the news release states. These poles were installed in Lower Chanceford and Peach Bottom townships in York County, as well as Drumore Township across the river in Lancaster County, where the facility is located.

No action by the public is necessary for either test, according to the releases.

— Sean Cotter covers York City for The York Dispatch. Contact him at or on Twitter at @SPCotterYD.

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