Completely robotically maintaining a complex machine sounds like a hard robotics problem to me. Of course it can be designed for machine manipulation but that seems like a pretty complex fusion of robotics and nuclear reactor design. So I think it would be a lot of work.

It seems to me that the simplest reactors tend to be the most dangerous. I'm thinking of the Windscale fire and SL-1 in particular. One of the theories for what went wrong at SL-1 is that it was a murder-suicide, caused by the man tasked with physically manipulating the control rods of the reactor. I think robotic control is better for something like that. Robots are more predictable.

One of the aggravating factors at Windscale was their inability to perform maintenance tasks behind the reactor. They had canisters of radioactive material smashing open behind the reactor and it took them ages to even notice. That was a very simple reactor design; basically a nuclear pile. It was also an awful design that was irradiating England even before it caught fire.

The Windscale reactors were built in a hurry in 1950 to produce nuclear weapons after Russia managed to test it's first atom bomb in 1949 and are not really representative of modern power generating technology.

Obviously Windscale wasn't modern and SL-1 certainly wasn't either. My point was that simple designs are poor designs, that modern designs are complex for good reason. The added system complexity of automation is well worth it when it comes to nuclear power.

Mostly hard robotics side. This is about replacing people and you don’t send people into heavy radiation areas. It’s like cleaning skyscraper windows, the overhead of keeping people safe is significantly more of an issue than just washing windows.

Decontamination and radiation mostly make it more expensive rather than more difficult.