Antares Mark-0 has achieved initial criticality! ⚛️

I am so proud of the @AntaresNuclear and @INL staff who executed this. I want to reiterate how this fits into our larger roadmap to mature our technology to its commercial potential. This should be obvious, but the goal of a reactor is to sell electricity to customers. Now that Mark-0 is critical, the real work is just beginning. Following our reactor physics experiments, we will execute the next phase of our roadmap — sustained electricity production. We are able to move fast towards this milestone because we’ve already completed over 6 months of full-power thermal testing in an electrical prototype. We will perform version 2.0 of this in 2026. This is an easier, more iterative way to test, because there is no regulatory process, and you can disassemble to examine material effects. All of our iterative testing sets us up to produce electricity for 6+ months. Hundreds of days, not hundreds of hours. We’re able to test for longer and faster because we’ve designed our reactor around a proven, fully qualified fuel spec developed under Project Pele.

Amazing. Congrats Jordan and Antares team!

Thank you, Tom!

Congrats to the Antares team!

Thank you! We’re working to 6 months of full power producing electricity fyi. 150hrs is only 6 days.

Next steps - 1) power conversion testing w/o reactor connected in the next couple months, then 2) power conversion with reactor connected in 2026 (?), then 3) operate at full power for 6 months and produce electricity, then 4) move onto Mark-1?

Yes exactly could combine steps 2 and 3 though.

@jordanbramble tremendous work to you and the team. From all of us @ENERGY, thanks for leading the charge!

@annasofialesiv Congrats Jordan

@annasofialesiv Thank you sir!

Amazing accomplishment, great job! It was such a thrill to share the moment with you.

Congrats!!!!!

@AntaresNuclear Congratulations, @jordanbramble and @AntaresNuclear. Awesome achievement! 🇺🇸 💪

Congratulations!! Awesome

let's gooooo, can't believe how much you've done in three years

@AntaresNuclear Congratulations to you and the team!

Congratulations!!!

Congratulations! Huge milestone. Here’s many more criticality successes!

lfg

LFG

Can you tell us about the reactor? What are some of the features that distinguish it from other designs? And what are the advantages over conventional nuclear?

Awesome stuff. Congrats!

Never doubted this team for a second! Couldn't be prouder!

@shaheersan This is amazing

what a day to remember with so much more ahead. keep going! usa usa usa 🇺🇸⚛️🚀💪

Huge congrats to the entire Antares team!

Boom

LFGG!! congrats!!

Congrats, Jordan, Julia, and the rest of the Antares team! Well done!

Congratulations!!

goo @jordanbramble !

@AvvocatoAtomico @GiZollino @KersevanRoberto @Amphsicora

Congrats team!! Fantastic work.

@chadbyers LFG!!!

We are so back. 🇺🇸☢️

a brilliant young man with clearly a brilliant team!

Wish more people knew this was happening right now!

Way to go Jordan And team. !!