Nobody wants to be that guy who has to rewrite the nuclear power plant software.

I do wonder what they use. I assume off-site computers aren't really an option for networking reasons, so Stratus, NonStop, z mainframes, etc probably. I wonder if they have a backup mainframe, or if the redundancy in one of those things is enough.

>Nobody wants to be that guy who has to rewrite the nuclear power plant software.

Nobody is allowed to rewrite the nuclear power plan software. My first job was at Westinghouse Nuclear Division. Those Fortran libraries were off-limits in terms of changes.

No surprise, same story in energy balance circle management to calculate the optimal schedule.

> energy balance circle management

WTF? What is energy balance circle management?

When you are creating a schedule for all the power plants taking into consideration predictions for home and industrial users and trading as well. There can be domestic and foreign trading involved as well. Not sure how it is called in English.

Is there a good move here? Update or not?

I used to work at a computer museum and we had an old computer from the 60s that was used in a plant and they came back and took it because they were upgrading their main computer and they wanted to keep redundancy I.E a backup for their backup.

In short, yes. They always have two machines running ready to swap in. I have heard some also run multiple live mainframes to check that the results agree, and discard and restart calculations if they don't.

For example systems like RC 4000.

http://brinch-hansen.net/papers/1967b.pdf

Also I heard part of the reason is that those systems are trivially maintainable on-site; if something breaks, you take out a soldering iron and a box of spare capacitors, and go fix it.