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Alert

The NRC is shutdown due to the lapse in appropriations. Exempted activities to maintain critical health and safety activities and progress on critical activities, including activities outlined in Executive Order 14300, as described in the OMB Approved NRC Lapse Plan will continue.

Terrestrial radiation

The portion of the natural background radiation that is emitted by naturally occurring radioactive materials, such as uranium, thorium, and radon in the earth.

Page Last Reviewed/Updated Tuesday, March 09, 2021

Page Last Reviewed/Updated Tuesday, March 09, 2021