RICHLAND, Wash. (AP) - A worker at the Hanford Nuclear Reservation got radioactive contamination on his clothing during an incident at an underground waste storage tank.

Contractor Washington River Protection Solutions says the worker was pulling a robotic device out of the space between the double walls of Tank AZ-101 on Thursday evening.

Monitors detected radiation at three times the expected level and the workers left the area.

The contractor says contamination was found on one worker's protective clothing, which was removed. Monitors showed no further contamination on that worker, and all members of the crew were cleared for normal duty.

Last week, a tunnel collapsed at the nuclear reservation. Workers scrambled to fill the hole left behind, but the area remained restricted.

More: Hole filled at Hanford tunnel collapse

Hanford is located near Richland and for decades made plutonium for nuclear weapons. Much of the waste produced by that work are stored in 177 underground tanks.

Welcome to Hanford: 'The most toxic place in America'