DOE Awards Three Nuclear Energy Vouchers to Constellation, NANO Nuclear, NuCube

Six weeks after closing a $13 million funding round, Idaho Falls microreactor startup NuCube Energy landed Argonne National Laboratory access to prove its solid-state DeccaCell reactor can start, monitor itself, and run without an operator on site. The same DOE voucher round, announced April 2, also paired Constellation Energy and NANO Nuclear Energy with Oak Ridge National Laboratory for analyses each company needs before its next NRC interaction.

The three awards came from the second round of FY2026 nuclear energy vouchers through the Gateway for Accelerated Innovation in Nuclear program, hosted at Idaho National Laboratory. The vouchers do not cut checks: "GAIN voucher recipients do not receive direct financial awards. Vouchers provide funding to DOE laboratories to help businesses overcome critical technological and commercialization challenges." Each recipient carries a minimum 20 percent cost share obligation. What the awards buy is dedicated time with national lab staff, access to validated simulation codes, and technical documentation that carries regulatory weight.

Constellation's project targets a specific operational question in boiling water reactors: moisture carryover behavior during power uprate and under normal operating conditions. Excess moisture in BWR steam degrades turbine performance and accelerates component wear. Answering the uprate question through ORNL's modeling resources is substantially faster and cheaper than an instrumented in-reactor test campaign, and the results feed directly into any uprate license amendment the Kennett Square, Pennsylvania-based operator submits to the NRC.

NANO Nuclear's ORNL engagement sits deeper in the pre-licensing stack. The New York-based company will use the SCALE/TSUNAMI code suite to run uncertainty quantification and sensitivity analysis on its reactor design. TSUNAMI is the criticality safety toolkit NRC reviewers lean on when stress-testing criticality claims in license applications. Having clean, ORNL-validated UQ results in hand means NANO Nuclear can answer that question before it arrives as a Request for Additional Information during formal review.

NuCube's DeccaCell is a solid-state fission design producing up to 15 megawatts for seven to 30 years before refueling, sized to ship by road or rail and operate autonomously at remote industrial sites and data centers. Argonne will construct a digital twin of the reactor and use it to verify NuCube's autonomous control architecture through simulated automated startup, remote monitoring, and predictive maintenance scenarios. For a reactor explicitly designed to run without on-site operators, demonstrating that autonomous capability to NRC satisfaction is not a peripheral requirement. It is the licensing question.

GAIN exists at Idaho National Laboratory precisely to fund this kind of work: too applied for basic research allocations, too expensive for early-stage companies to staff unassisted. Each voucher converts a technical unknown into a documented deliverable before a formal license application is filed, which is how DOE compresses the timeline between a promising reactor concept and an NRC-ready filing.

Watch for ORNL deliverables from the Constellation moisture carryover study and NANO Nuclear's SCALE/TSUNAMI analysis in the months ahead. On the NuCube side, any NRC pre-application meeting notices or early license filings referencing Argonne's autonomous control verification data will signal how quickly that $13 million raise is translating into regulatory momentum. The third FY2026 GAIN voucher round closes April 30.