Nope, pretty sure I'm not. I'm well aware that LFTRs run at low (even sub-atmosphere) pressures.

>We built and ran LFTRs commercially in the 1950s in New York State and Pennsylvania

We never ran LFTRs commercially. If you know otherwise, please cite. I only know of two experimental reactors at the Oak Ridge facility: the Aircraft Reactor Experiment and the Molten-Salt Reactor Experiment.

> I don't know where you got that idea.

I got that idea from some pretty simple facts about nickel alloys (like Hastelloy N) under neutron bombardment.

When you bombard nickel with neutrons, you produce helium. When the helium builds up irregularly, the alloy becomes brittle. You can dope Hastelloy N with titanium or niobium to even out the distribution of helium deposits (this is what ORNL did) but that brings the maximum temperature down to 650C.

As well, tellurium (one of the fission products of a LFTR reactor) corrodes the grain boundaries of Hastelloy N. You can reduce this effect by doping it with niobium and keeping the UF4/UF3 ratio to less than 60.

You have to trade off lower temperatures with whether or not you want to deal with beryllium toxicity. You can replace BeF2 with a eutectic lithium fluoride/thorium fluoride composition, but that requires an increased temperature of the reactor salts. There are other problems with using beryllium, though - it produces lithium-6, which is a strong neutron poison.

You also have to filter out noble element deposits, because they don't form fluorides.

There are also serious design challenges with modifying current turbines to work with supercritical CO2 or helium. You can use supercritical steam instead, but it isn't nearly as efficient.

You also have to worry about tritium diffusion. It's small enough that it leaks through the heat exchangers.

There are issues with the rapid expansion/contraction the graphite moderator, but some are working on graphite pebble designs.

Once you throw the corrosive salts, strange reaction byproducts, and neutron bombardment into the mix, I highly doubt that 'the average body shop' could pull off the fabrication of a LFTR style molten salt reactor that could run safely for longer than a week.