Multiscale Mechanistic Insights into Hydrogen Production from Microalgae via Molten Hydroxide-Mediated Thermochemical...

[John ONeill]

2. Sodium hydroxide as a neutron moderator

The Danish small reactor company Seaborg Industries (named after the great Swedish-American chemist) was working on using molten NaOH as a low-pressure, high-temperature moderator for their molten salt reactor design. They must have hit a roadblock, as they've now reverted to more conventional graphite, and also changed their name to Saltfoss Energy.
Similarly, Transatomic Power a few years ago proposed zirconium hydride (maybe stabilised with yttrium hydride) as a moderator. Eventually they had to admit that their neutronics calculations were way too optimistic, and they're now out of business. Aalo Atomics, more recently, were going to use uranium zirconium hydride fuel, like the TRIGA research reactors, but in a sodium-cooled reactor. There was some doubt about how soon the hydrogen would migrate out of the fuel at high temperature; in the end Aalo went for UO2 and graphite, mainly because supply could be guarranteed sooner. At least they'll be well set up to switch to a fast spectrum sodium design, if they're successful.