Infrared cameras on a boat accompanying the rig as it was being towed detected no signs of leakage early Monday, according to the unified incident response command, which includes the Coast Guard, Alaska's state environmental conservation department, a drilling company and Kodiak Island officials.

CNN: Alaska drilling rig towed to harbor off Kodiak Island

In order to do this the company needs to hermetically seal the drives to prevent He gas leakage over the life of the drive no mean feat.

FORBES: Rare Gases and Fine Lines