Amid the AI boom, nuclear power is in vogue, with venture capitalists lining up to plow hundreds of millions into small modular reactor (SMR) startups to make their datacenter energy headaches go away.

On Wednesday, Radiant, an El Segundo, California-based startup founded in 2020, said it raised more than $300 million in a funding round led by Draper Associates and Boost VC to commercialize its semi-trailer-sized microreactors.

The company expects to break ground on an SMR manufacturing plant in Oak Ridge, Tennessee next year.

[1]

"This funding enables us to build our factory and keep to our DOME schedule, where we will achieve a self-sustained chain reaction on a reactor designed by, built by, fueled by, and operated by Radiant alongside our partners at the Idaho National Lab," Radiant CEO Doug Bernauer said in a canned [2]statement .

[3]

[4]

DOME refers to Idaho National Laboratory's Demonstration of Microreactor Experiments project, where Radiant says it's on track to flip the switch on its first reactor, the Kaleidos Demonstration Unit (KDU), sometime next year.

Unlike other SMR designs we've discussed over the past year, Radiant's Kaleidos reactors are tiny, capable of producing about a megawatt of power each. However, the actual mechanism for energy generation isn't too far off from the designs we've seen from [5]X-Energy , which use TRISO fuel pellets and helium gas as a coolant.

[6]

Thanks to their size, Radiant says they can be transported using standard semi-tractors and refueled up to four times over their 20-year lifespans.

[7]

Radiant says its Kaleidos reactor design can be transported via semi-trailer and is capable of producing up to a megawatt of power - Click to enlarge

However, from a datacenter standpoint, a megawatt just isn't that much power anymore. Modern rack systems from Nvidia are pushing 140 kW each with next-gen designs targeting 600 kW, beginning in late 2027. As such, datacenter operators would need at least two Kaleidos for every three Nvidia Kyber racks deployed.

But that's not stopping datacenter operators including Equinix from going all in on the tech. In August, the colocation giant [8]revealed it'd preordered 20 of Radiant's Kaleidos reactors.

[9]US freezes $42B trade pact with UK over digital tax row

[10]Trump's AI 'Genesis Mission' emerges from Land of Confusion

[11]US Navy pledges $448 million to test if Palantir is seaworthy

[12]Meta and Google turn to NextEra to feed insatiable datacenter power hunger

Equinix is one of several large bit barn operators that've thrown their weight behind backyard atomics. Amazon is investing in both conventional nuclear and SMRs in order to unburden itself from relying on US grid operators. Google and Oracle are also investing in SMR startups, while Microsoft is funding the re-ignition of the Three Mile Island Unit 1 reactor — you know the one that didn't partially melt down in the late 70s.

However, the jury is still out on whether SMRs will ever be cost effective. In September, analysts at the Centre for Net Zero (CNZ) [13]estimated it would cost 43 percent less to power a 120 MW data facility with renewables and a small amount of gas-generated energy, compared to using SMRs. ®

Get our [14]Tech Resources



[1] https://pubads.g.doubleclick.net/gampad/jump?co=1&iu=/6978/reg_specialfeatures/futureofthedatacenter&sz=300x50%7C300x100%7C300x250%7C300x251%7C300x252%7C300x600%7C300x601&tile=2&c=2aUM2C1NhMxPmj56lBUIhOAAAARg&t=ct%3Dns%26unitnum%3D2%26raptor%3Dcondor%26pos%3Dtop%26test%3D0

[2] https://www.radiantnuclear.com/blog/series-d-announcement/

[3] https://pubads.g.doubleclick.net/gampad/jump?co=1&iu=/6978/reg_specialfeatures/futureofthedatacenter&sz=300x50%7C300x100%7C300x250%7C300x251%7C300x252%7C300x600%7C300x601&tile=4&c=44aUM2C1NhMxPmj56lBUIhOAAAARg&t=ct%3Dns%26unitnum%3D4%26raptor%3Dfalcon%26pos%3Dmid%26test%3D0

[4] https://pubads.g.doubleclick.net/gampad/jump?co=1&iu=/6978/reg_specialfeatures/futureofthedatacenter&sz=300x50%7C300x100%7C300x250%7C300x251%7C300x252%7C300x600%7C300x601&tile=3&c=33aUM2C1NhMxPmj56lBUIhOAAAARg&t=ct%3Dns%26unitnum%3D3%26raptor%3Deagle%26pos%3Dmid%26test%3D0

[5] https://www.theregister.com/2025/10/17/amazon_nuke_washington/

[6] https://pubads.g.doubleclick.net/gampad/jump?co=1&iu=/6978/reg_specialfeatures/futureofthedatacenter&sz=300x50%7C300x100%7C300x250%7C300x251%7C300x252%7C300x600%7C300x601&tile=4&c=44aUM2C1NhMxPmj56lBUIhOAAAARg&t=ct%3Dns%26unitnum%3D4%26raptor%3Dfalcon%26pos%3Dmid%26test%3D0

[7] https://regmedia.co.uk/2025/12/17/kaleidos_reactor.jpg

[8] https://www.theregister.com/2025/08/14/equinix_signs_deals_for_nukes/

[9] https://www.theregister.com/2025/12/16/us_uk_trade_deal/

[10] https://www.theregister.com/2025/12/11/doe_genesis_mission_funding/

[11] https://www.theregister.com/2025/12/10/palantir_navy_448_million_contract/

[12] https://www.theregister.com/2025/12/08/nextera_meta_google_datacenter_power/

[13] https://www.theregister.com/2025/09/26/renewables_vs_smr_datacenter/

[14] https://whitepapers.theregister.com/