Nuclear is significantly more efficient today than many years ago. The amount of Nuclear waste that the U.S. has produced since the 1950's is the size of a football field and 10 feet deep. It's really not that much.
The bigger looming problem is climate change, and Nuclear is the only true way to produce clean consistent power in the short term. Wind and Solar are great, but they don't produce on-demand power. Especially when the power grid will start seeing significantly more electric cars on the grid in the next decade. Nuclear is the technology we have today, which can do the work we need.
The only real drawback of Nuclear are safety concerns, and localized nuclear waste(not atmospheric). As well as the price tag to build a nuclear plant. It's not really economically viable in the U.S. because electricity prices are so cheap. Once you start charging 30-40 cents per kwh, then nuclear plant financials make more sense.
In this article, I guess this power company has found a way to make their Nuclear plant more economically viable, using crypto to supplement income from unused capacity.