I think the reason they were trying to use water cannons was because of the great range they offer in shooting water. They needed that range because humans cou

I think the reason they were trying to use water cannons was because of the great range they offer in shooting water. They needed that range because humans couldn't go near the pools containing the spent fuel rods because of the radiation. But if a robot could get very close, they might not need to use a water cannon, and could use just a regular water hose. Or they might be able to use a water cannon but with water coming out at a much lower pressure. And I'm not sure that the hose dragging is an unsolvable engineering task either. They could, for instance, erect a tower with a spool of hose on it. As the robot moved away from the tower and towards its destination, it could unravel the hose from the spool and have most if not all of the hose be suspended in the air behind it. Another solution could be to have a second robot following the first, to support a portion of the hose. They could even use a third or a fourth robot behind the first two, if needed. Those are just off-the-cuff ideas.. I'm sure professional engineers could easily think of dozens of other methods to solve the hose-dragging problem.