Amazon today became the latest major tech company to throw its weight behind nuclear power, joining Microsoft and Google, which earlier this year both announced long-term promises to buy nuclear power from startups to power their data centers.

The company unveiled three deals, including an investment in startup X-Energy and two development agreements that will add capacity to around 300 megawatts each in the Pacific Northwest and Virginia, two of the hottest data centers markets.

The two development deals describe the building of small modular reactors. These produce a fraction of the power produced by contemporary nuclear power plants but which proponents say will be faster and cheaper to build. Amazon expects that the reactors will start generating electricity in the early 2030s.

In the Pacific Northwest, the deal with the Energy Northwest consortium of state public utilities will underpin four SMRs that will generate around 320 megawatts combined. Expansion could push the total generating capacity up to 960 megawatts -- enough to power about 1 million homes. In Virginia, Amazon and Dominion have agreed to "explore the development" of 300 megawatt's worth of SMRs near the North Anna located between Washington, D.C., and Richmond.

Those will probably be using the X-Energy technology-a Small Modular Reactor startup based in Rockville, Maryland. Amazon's Climate Pledge Fund led a new $500 million Series C-1 in the company and invested alongside Citadel founder Ken Griffin, NGP, and the University of Michigan. Add that to the $385 million the company has raised so far, according to PitchBook.

X-Energy specializes in high-temperature gas-cooled reactors-an approach that fell out of favor in the U.S. and Europe but, as new designs emerged, was more recently revived in Japan and China.

When constructed, X-Energy's Xe-100 reactor will produce 80 megawatts of power. Its fuel is uranium, three layers of carbon coat the kernels, and 18,000 of those grains the size of poppy seeds are then loaded into a "pebble" the size of a billiard ball, and 200,000 of those pebbles are used in each reactor. Helium flows between the pebbles, where it's heated to 750 degrees C. That heat is then transferred to water, which generates steam to spin a turbine.

The system, known as TRISO, represents a much safer nuclear fuel than the designs of nuclear fuel currently used, wherein the particles containing the uranium are kept at extremely high temperatures.

The first reactor is to be built at a Dow chemical plant outside Corpus Christi, Texas. The company hasn't said when the project will be completed. The company said that it plans to develop as much as 5,000 megawatts of new nuclear power throughout the U.S. by 2039.

And just like the deal that Google announced on Monday with Kairos, the new deals with Amazon give a boost to nuclear fission amidst fast growth on nuclear fusion and the steady march of power from renewable sources, such as solar and wind, which have made considerably cheaper during the last ten years. In truth, nuclear power is pervasive, though new reactor designs remain commercially unproven; their timeline pits them in competition with other carbon-free sources of power that promise to commit to decarbonizing the electrical grid in the coming decade.