Boston Police officer John Quinn walks with, Miller, his bomb detection canine, over the finish line while sweeping the area in preparation for the Boston Marathon, Wednesday, April 16, 2014, in Boston. (AP Photo/Charles Krupa)
The Boston Marathon finish line is one area along the route being monitored by a helicopter for radiation tests by the National Nuclear Security Administration.
AP

This week, you may have noticed a helicopter buzzing around the city. The aircraft belongs to the National Nuclear Security Administration, which is conducting radiation tests around the Boston Marathon area to protect against a potential nuclear terror attack on Monday.

The Boston Globe reported:

The establishment of background radiation is done so that if radiation is detected during the Marathon, authorities can distinguish between normal levels and possible terrorist activity.

Advertisement - Continue Reading Below

The twin-engine Bell 412 helicopter is equipped with radiation sensing technology, according to the National Nuclear Security Administration, and will be conducting flyovers multiple times a day this week.

The helicopter will be low-flying and fast-moving, The Weekly Standard reported.

The twin-engine helicopter out of the military's Joint Base Andrews in Maryland will fly a grid pattern as low as 150 feet above the ground at 80 miles per hour, though only during daylight hours.

The radiation monitoring is “a normal part of security and emergency preparedness,” according to NNSA.

The operation started Thursday and will last through Sunday.