Four advanced reactor projects hit zero-power fueled criticality by 4 July 2026 — beating the Trump administration's goal of at least three — and House Science, Space, and Technology's Energy Subcommittee put that receipt on the record on 2 September under the hearing title "Powering the Nuclear Renaissance."

Randy Weber chaired the Energy Subcommittee frame. Antares, Valar, and Aalo were among the industry witnesses tied to the criticality set. HALEU fuel-supply gaps sat in the same oversight conversation. This is the criticality-and-hearing story, not the six nuclear bills that cleared Energy and Commerce the same week.

Criticality, defined for a civilian paper: a reactor is critical when it sustains a nuclear chain reaction. Zero-power fueled criticality means fuel is loaded and the chain reaction is demonstrated at negligible power — an engineering gate, not a commercial operating licence and not a grid megawatt claim. The administration's Reactor Pilot Program goal, rooted in executive-order language on reforming nuclear reactor testing, asked for at least three advanced reactor concepts outside national-lab-only pathways by Independence Day 2026. Four made the cut by that date.

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Name the four as the hearing charter and DOE colour name them. Antares Nuclear's Mark-0. Valar Atomics' Ward 250. Deployable Energy's Unity (Nuclear Energy Launch Pad context in the charter). Aalo Atomics' Aalo-X, timed in early hours of 4 July in the committee materials. A fifth — Oklo's Groves Isotope Test Reactor — reached criticality in early August on the same oversight narrative, after the July 4 scoreboard. The headline four are the Independence Day exceedance. Report the fifth as later colour, not as rewriting the July tally.

Witness table on 2 September 2026 in 2318 Rayburn: Oak Ridge's Joe Hoagland; Valar's Isaiah Taylor; Aalo's Matt Loszak; North Carolina State's Steven Shannon; Antares' Jordan Bramble. Three of the companies that hit the summer milestones sat in the chairs. Weber's opening statement called the four zero-power fueled criticality demonstrations a goal met and exceeded by America's 250th birthday, with DOE support through the Reactor Pilot Program and related launch-pad pathways.

HALEU — high-assay low-enriched uranium — is the fuel noun that keeps showing up when advanced reactors leave slideware. Hearing materials and trade coverage note supply-chain pressure for HALEU as a deployment bottleneck even when criticality demos succeed. Note the gap. Don't invent a tonnes-per-year figure the hearing didn't settle on the public summary. Fuel availability is a parallel industrial story to the criticality scoreboard.

Separate from the six nuclear bills. Energy and Commerce's early-September markup advanced bipartisan permitting reforms toward the House floor — REFUEL, enrichment deployment, licensing hearings, advisory and pay alignment, DOE transparency. That's legislative process. This Science hearing is oversight of hardware milestones and DOE's role in advanced reactor demonstration. Same renaissance vocabulary. Different committee, different verb.

Numbers. Goal: at least three advanced reactor zero-power fueled criticalities by 4 July 2026. Result: four by that date — Antares, Valar, Deployable Energy Unity, Aalo among the named set. Hearing: House SST Energy Subcommittee, 2 September 2026, "Powering the Nuclear Renaissance." Chair frame: Randy Weber. Witnesses include Antares, Valar, Aalo CEOs and founders. HALEU supply gap: noted in oversight context. Sources: House SST hearing pages and charter, September 2026; Weber opening statement; DOE and trade criticality tallies.

Why zero-power matters without overselling. A criticality demo proves physics and assembly quality under a controlled test protocol. It doesn't prove years of high-power operation, a licensed commercial plant, or a data-centre power purchase agreement. Weber's renaissance language and the witness list are political and industrial attention. The gate is still a gate. Readers who conflate criticality with "online megawatts" get corrected in the second breath.

Reactor Pilot Program geography. DOE's 2025 selections put a roster of advanced developers into an expedited demonstration pathway; the September charter recounts that selection history as backdrop. National-lab sites and partner test beds hosted several of the 2026 demos. The goal language emphasised concepts located outside a pure national-laboratory-only story even when lab facilities supported the tests — read the charter's own wording when you need the legal nuance. I'm staying with the public scoreboard: four by 4 July.

China competition and AI load language showed up in preview coverage of the hearing week as the political weather around firm clean power. Useful climate for why a Science subcommittee booked a renaissance title. Not a substitute for the criticality facts. Keep the weather in one paragraph and the reactors in the rest.

No invented thermal megawatts. No claim that any of the four is selling power to ERCOT tomorrow. No conflation with the Energy and Commerce permitting six. No HALEU tonnage invented from a think-tank PDF. No fifth-reactor-on-July-4 rewrite. Antares, Valar, Aalo as hearing witnesses — yes. Deployable Energy Unity as part of the four — yes on the charter tally.

Abundance register, American. Four private-developer-linked criticality demos before a national birthday is the kind of dated hardware progress oversight hearings exist to certify in public. Pair it with the honest constraint: fuel supply, licensing after the pilot pathway, and capital for first-of-a-kind plants remain open problems. Progress is four cores that went critical. Policy is what Congress and DOE do next.

Dates again. Goal deadline: 4 July 2026. Four criticalities by then. Hearing: 2 September 2026. Committee: House Science, Space, and Technology — Energy Subcommittee. Title: Powering the Nuclear Renaissance: Accelerating U.S. Leadership in Advanced Nuclear Reactors. Weber in the subcommittee chair's opening frame. Babin on the full-committee opening slate per the hearing page. Witnesses as named above.

International readers get the same spine without the parade language. United States advanced-reactor developers demonstrated four zero-power fueled criticalities by the administration's July 4 target of three; Congress held a renaissance-titled oversight hearing on 2 September with three of those firms in the room; HALEU supply remains a noted constraint. That's the exportable paragraph.

Close. Trump administration goal of at least three advanced reactor zero-power fueled criticalities by 4 July 2026 was exceeded with four — Antares, Valar, Deployable Energy Unity, and Aalo among the named set — and House SST's 2 September hearing, Randy Weber in the Energy Subcommittee frame, put Antares, Valar, and Aalo among the witnesses under "Powering the Nuclear Renaissance." HALEU supply gap noted. Distinct from the Energy and Commerce permitting bills. Sources: House SST September 2026; Weber opening statement; DOE and trade tallies. Four hit criticality. The hearing read the receipt.