Tune in to CNN tonight at 9 ET for special editions of "In the Arena," "Piers Morgan Tonight" and "AC360º." Anderson Cooper, Dr. Sanjay Gupta and Soledad O'Brien report live from Japan on the quake and tsunami's catastrophic effects.

(CNN) -- Tests detected low levels of radioactivity on 17 U.S. Navy helicopter crew members when they returned to the USS Ronald Reagan after conducting disaster relief missions in Japan, the military said Monday.

No further contamination was detected after the crew members washed with soap and water, the Navy said.

In addition, the Navy said the U.S. 7th Fleet has temporarily repositioned its ships and planes away from the Fukushima Daiichi nuclear power plant after detecting low-level contamination in the air and on its planes in the area, the Navy said.

One ship was operating about 100 miles northeast of the power plant when "airborne radioactivity" was detected, the Navy said.

The Navy's statement, however, provided some perspective, noting that the maximum potential radiation dose received by personnel when the ship passed through the area was "less than the radiation exposure received from about one month of exposure to natural background radiation from sources such as rocks, soil, and the sun."

On Sunday, the USS Ronald Reagan started delivering aid in the coastal regions of Japan's Miyagi prefecture.

Crew members, in conjunction with the Japan Maritime Self Defense Forces, conducted 20 sorties delivering aid pallets.

Eight U.S. and Japanese helicopters were used to distribute the pallets, according to Sgt. Maj. Stephen Valley of U.S. Forces Japan.

Workers are scrambling to cool down fuel rods and prevent a full meltdown in three reactors at the earthquake-hit plant. Radioactive steam has been released, intentionally to lessen growing pressure in the reactors.