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Comment by GTP | Hacker News Reader

There are a few things I don't get of the fifth point: why do we need to be able to operate nuclear fusion plants remotely? Wouldn't it be not just possible, but maybe even preferable, to have staff on site to manage the plant, like it is the case for fission plants? And if we still want remote control, why is this such a big challenge? With a background in computer engineering and cybersecurity, this seems to me the smallest challenge of the list.

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I think they mean that we shouldn't have to send a guy inside the reactor to clean and reset it up every time you fire it. I don't really know why they listed this point.

Seeing it from this perspective, maybe I now see it: the residual radioactivity inside the reactor may be strong enough to mess with the electronics of a robot you're sending inside. Maybe there are challenges in getting enough shielding while keeping the robot reasonably sized and maneuverable.

A major challenge is getting the robot into the place you need it, along with other objects it needs like replacement parts, in between the other infrastructure like coils and cooling blankets. You mustn't damage the delicate reactor structures, you can't have rails and so on always in the reactor vessel, the vessel has to be vacuum tight, and most of all you must not allow the robot to fail and be unextractable, because humans can't go in an pull it out.

ITER seems to have a project called the Agile Robot Transporter which you can see some renders of that demonstrate how fiddly this problem is.

This presentation has some useful illustrations about the ART:

https://indico.iter.org/event/45/contributions/1090/attachme...

Maybe because of security, and the entire thing needs to be airgapped.

Remote handling might refer to robotics or remote control done on site. Fusion does produce neutrons that will generate some radio activity in structures and so on. Minimising humans needing to be close these is reasonable move.

> like it is the case for fission plants

Fission plants are operated remotely. IE, that's what the stereotypical "control room" of a fission plant is.

It's more to the point that disruptions tend to be very disruptive, too frequent, not well understood, and the reset takes a really long time. But you're right that this does not quite belong. If we solve the technological problems, the maintenance should resolve itself.

Making the reactor sufficiently maintainable is a technology problem.

There was a group that tried to analyze the expected uptime of DEMO, the pre-commercial follow on to ITER. With the expected MTBF (mean time between failure) and MTTR (mean time to repair) they estimated it would be working just 4% of the time. That's too low even for a research machine.

RAMI (reliability/availability/maintainability/inspectability) is one of the major issues for fusion, and even if nothing else stops fusion it alone will make the development process very long and iterative. Good RAMI requires long iterative improvement of individual components and processes.

is it remote from the reaction chamber? i.e. if people have to go in to wipe/re-coat stuff, it takes longer to do it safely, but it's cheaper/faster if you can get a machine to do it with the people controlling it from a distance. still, doesn't seem terribly hard, when surgery has been done with remote controlled robots.

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