About 50 workers were exposed to airborne contamination at the Peach Bottom Atomic Power Station on Tuesday morning, according to a notification from the U.S. Nuclear Regulatory Commission.

Outage workers taking apart the Delta plant's Unit 2 reactor were exposed when steam discharged from the flange, "causing a small but detectable amount of airborne contamination that was contained in the building," the report said.

The affected employees were wearing proper protective equipment, and no significant exposure has been reported, according to the NRC.

Workers were asked to temporarily leave the area as a precaution and were evaluated onsite while radiation protection technicians conducted an investigation, the report said.

Radiation monitors, which initially identified the contamination, have returned to normal levels, and the event resulted in "no significant impact to the health and safety of our workers or the public," according to the NRC.

Experience and commitment to safety were important factors early Tuesday morning as outage workers on the Unit 2 refuel floor responded quickly and effectively to a detectable level of airborne contamination, according to David Tillman, spokesman for Exelon Corp., Peach Bottom's parent company.

"The discharge was small, brief and contained," he said.

All 138 outage workers in the area responded appropriately, and each person was closely monitored by radiation protection technicians with highly sensitive equipment, Tillman said.

"Of the 138 workers, only 47 required any additional monitoring and not one received significant exposure. No threat to public health or safety existed," he said.

Exelon is currently investigating the cause of the steam discharge and will share any lessons learned with its fleet of nuclear generation companies and industry partners, Tillman said. Peach Bottom also made courtesy notifications to the NRC, the State Bureau of Radiation Protection, and state and local stakeholders in keeping with the company's proactive outreach policy, he said.

NRC officials were not immediately available to confirm if they would be hosting follow-up inspections or any other safety measures at the site.

- Candy Woodall can also be reached at cwoodall@yorkdispatch.com.