[chimera]

Embrittlement of metal generally requires displacement damage and gamma radiation is not terribly efficient for doing that. You generally need high-energy neutrons, and you aren’t going to have those in any kind of fuel residue, at least not in significant quantities. Gammas cause ionization and eventually heat, and can damage junction devices, but the metal itself is not likely to be degraded by exposure to gamma sources.

[flamberge]

After the engineers have worked out better shielding methods for remote control systems, the robots will have long enough life spans that embrittlement will become an issue. This is particularly true for machines that must be designed to work on the melted core elements.

They will also need very clever mechanical designs that allow field replacement of major working elements by remote-controlled repair robots.

Think of a remote-controlled earth mover or front loader that is fueled, maintained and serviced by remote-controlled mechanics.

None of these machines will ever leave their work areas until they are removed by remote-controlled disposal vehicles, and transported to a dump zone.

It will be a very complex mechanical ecosystem requiring very smart people to build and operate it over many decades.