It's unusual to find a news release as fascinating as a thriller. But this is the case with this story about the adventures of 'Mighty Mouse,' a robot used at Sandia National Laboratories to free a stuck deadly radioactive source and to safely return it to its insulated base. It took four days to M2, as this robot is also called, and its operators, to achieve the task. During these four days, the 600-pound, five-foot-long robot M2 was frozen by radioactivity and some of its components have been replaced by parts found at Home Depot.
Let's first look at the cause of the incident.
Alarms were blaring, warning lights flashing, and personnel were monitoring the stricken site around the clock in late October at the White Sands' Gamma Irradiation Facility. The cause was a stuck cylinder the size of a restaurant salt shaker but considerably more deadly: Gamma rays from the cobalt-60 it contained could kill a man in half a minute. Its radiation field was too deadly for a human, even in a protective suit, to get near enough to free it.
Usually, a small pressure of 20 psi (1.4 bar) is enough to move the container. But this time, even after applying an air pressure of 1,000 psi (69 bars), the technicians could not budge the cylinder. So they decided to call the local NNSA RAP team -- the Radiological Assistance Program -- which had a robot able to do the job.
The 600-pound, five-foot-long robot, which became unofficially known as M2, rolled on treads, could maneuver around obstacles, and had a long, multi-jointed gripper arm with the dexterity to reach into awkward places and apply force to drills and screwdrivers. It could remember positions, important in starting with tools at the right height and depth. It was intended as a bomb-disabling unit.
On the photograph below, an engineer demonstrates the capabilities of the robot affectionately known as the M2, for Mighty Mouse (Credit: Randy Montoya for Sandia). And here is a link to a larger version of this picture (1.38 MB).
But please keep in mind that M2 was not intended to face radioactivity: it was estimated that M2 could withstand intense radiation for only 50 minutes.
Now, here is a brief summary of this four-day effort.
On the first day, M2 tried to drill some holes in the steel plate of the radioactive cylinder to insert a probe inside. After four different attempts lasting one hour and a half, the robot's lower portion was no longer responding to commands. So it was pulled by a rope.
The next day was even worse. The engineers had to replace a damaged fiber optic line and to modify M2's tools after a visit at Home Depot.
It took two more days of effort before solving the problem and stopping the warning lights and horns that annoyed the personnel at White Sands during three weeks.
I guess that 'Mighty Mouse' is now enjoying a well-deserved rest.
Sources: Sandia National Laboratories news release, via EurekAlert!, December 15, 2005; and various web sites
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