The largest unit demonstrated in this video output 35 watts. Not quite 5 megawatts, lest anyone get the wrong idea. That's mentioned in the paper linked in the description.
https://sci-hub.hkvisa.net/10.2514/3.48057
> It is found that the Nitinol heat engine
capital costs per unit power generating capacity are approximately $0.15/W, and that the cost of produced
energy for the Nitinol heat engine portion of the power plant is approximately 0.74C/kWh, including operation,
maintenance, Nitinol replacements and the cost of capital for the heat engine. It is concluded that Nitinol power
plants for the conversion of low grade thermal energy may have a significant economical advantage over conventionally fueled power plants.
It seems like it has a huge potential in nuclear plants
That paper was analysing the system with a temperature difference of 40C (a temperature difference which doesn't allow you to extract energy efficiently anyway). Nuclear power plants at minimum produce steam at about 300C (all the way up to 900C). It doesn't seem like it the paper would particularly support its use for nuclear power. (Basically all plausible uses for this involve using low-grade power. But any system which attempts to do this needs to be really, really cheap compared to conventional systems to be worthwhile).