It's legit cool and inspiring that Valar obtained old General Atomics TRISO fuel and built it into an assembly that was brought critical using LANL infrastructure. This shows that they have great connections and can get things done. Big congrats! Of course, these are not the first VC-backed atoms to be split. TerraPower was splitting far more atoms at high power and high temperature using INL infrastructure (the ATR) more than 5 years ago. Whether enriched uranium will go critical is not interesting from an engineering point of view (of course it will). With a new fuel form, you want to run at high power and temperature so you can learn how it behaves in prototypic reactor conditions. Valar may indeed be the first VC-backed startup to put old General Atomics fuel in their own critical assembly and bring it critical at a LANL critical facility. Still cheering them on! The faster we get hardware running at commercially-relevant prototypic conditions, the faster we learn how to iterate and improve in nuclear power. Valar is showing everyone how to move fast, and it is impressive. I've heard engineers are larger, more established nuclear firms point to Valar's progress to beg their management to move faster.