JOINT BASE ANDREWS, Md. — The Department of Energy took delivery of three new radiation monitoring aircraft recently and put them on display here Wednesday at one of two home bases for the airborne leg of the agency’s counterterrorism office.

The three new King Air 350ER airplanes provided by Textron Aviation [TXT] of Wichita, Kan., will replace three 1980s-vintage aircraft the agency’s semiautonomous National Nuclear Security Administration (NNSA) used for decades to scan for traces of potentially harmful radiation.

Textron’s contract, which included the procurement of aircraft and integration of gamma ray spectrometers and other equipment, cost $32 million, an NNSA spokesperson wrote in an email Thursday.

One plane will be based at Joint Base Andrews near Washington, another at Nellis Air Force Base near Las Vegas. The third is a spare that will remain at Andrews. Aside from the flight to Andrews for Wednesday’s event, the three planes had mostly been airborne only during test flights in Wichita.

The NNSA deploys the Aerial Measuring System fleet, which includes a pair of helicopters in addition to the fixed-wing craft, both proactively and reactively. The aircraft are routinely sent to sweep for illicit nuclear materials at the sites of major public events such as presidential inaugurations or big-ticket sports games, but may also be sent out on call if local, state, or federal law enforcement suspect a radiological threat.

“These are fairly regularly used,” Jay Tilden, the NNSA’s associate administrator for counterterrorism and counterproliferation, said in an interview here. “Luckily, I can tell you that for a real world kind of a threat, like a malevolent threat, that has been very, very rare.”

The Aerial Measuring System planes could, if necessary, reach all 50 states, Tilden said. The new aircraft add creature comforts for crew members, such as larger seats, a makeshift head, and more space for large-monitor computer workstations. They also have five seats, compared with three in the old fixed-wing fleet, allowing more NNSA or other personnel to tag along on flights.

Both Lisa Gordon-Hagerty, the NNSA administrator, and Rep. Ron Estes (R-Kan.), whose district includes Wichita, were on hand to debut the new aircraft to a select audience of current and former agency employees, contractors, Capitol Hill staffers, and media.