Hadron Energy Submits Principal Design Criteria Whitepaper to U.S. Nuclear Regulatory Commission, Marking Pivotal Licensing Milestone for Halo Microreactor

Submission Advances Formal 10 CFR Part 52 Licensing Pathway for 10 MWe Passive Safety Reactor Ahead of Company’s Planned Public Listing

NEW YORK, NY —April 22, 2026— Hadron Energy, Inc. (“Hadron” or “Company”), a developer of advanced nuclear microreactors, announced the submission of its Principal Design Criteria (PDC) White Paper for Hadron’s Halo Modular Microreactor (Halo MMR) to the U.S. Nuclear Regulatory Commission (NRC) as part of the formal pre-application engagement process under 10 CFR Part 52 (Project No. 99902144). The submission, dated April 10, 2026, formalizes the technical and safety framework that will govern all future license applications for the Halo MMR, including a Manufacturing License (ML) and a combined Construction Permit and Operating License (COL). It builds upon the Company's prior regulatory filings including its Quality Assurance Program Description and Regulatory Engagement Plan.

The submission follows a productive pre-application meeting with NRC Staff on December 17, 2025, during which the NRC’s New Reactor Division, including senior technical reviewers from multiple branches, provided positive feedback on Hadron’s proposed regulatory approach. The NRC’s openness to Hadron’s PDC framework provides early validation of the Company’s licensing strategy and meaningfully de-risks the path to commercialization. The White Paper is submitted in direct fulfillment of the action item from that meeting.

A Licensing Strategy Built on Proven Regulatory Foundations

Hadron has selected 10 CFR Part 52 as its licensing pathway, which provides a combined COL process specifically designed for new reactor builds. Part 52 builds on the foundational regulatory principles established under Part 50 while offering a streamlined, design-oriented framework that resolves key licensing questions before construction begins. This approach reduces late-stage regulatory risk and aligns with the Halo MMR’s standardized deployment model.

Hadron's PDC approach is grounded in well-established NRC regulatory precedent for integral pressurized water reactor (iPWR) designs that rely on inherent passive safety rather than active engineered systems. The NRC has previously approved exemptions from certain General Design Criteria for this class of reactor, recognizing that prescriptive requirements designed for large active-safety plants are unnecessary — and in some cases inapplicable — when the underlying safety functions are achieved through passive physics alone. Building on this established regulatory precedent and favorable NRC feedback during early engagement, Hadron is well-positioned to demonstrate compliance with applicable regulatory requirements and rigorous safety standards.

The PDC White Paper addresses nine General Design Criteria (GDC) exemption areas, including Electric Power Systems, Control Room and Shutdown, Combined Reactivity Control, Reactor Coolant Makeup, Passive Fluid Systems, Containment Heat Removal Testing, Containment Leakage Rate Testing, and Containment Isolation. An additional eight non-GDC regulatory exemptions with an established precedent are also addressed. In every case, Hadron’s proposed PDC meets or exceeds the underlying safety objectives of the applicable requirement while reflecting the unique passive physics of the Halo MMR.

The Halo MMR: A New Standard in Passive Nuclear Safety

The Halo MMR is a 10 MWe integral pressurized water reactor (iPWR) of the “reactor-in-a-pool” configuration. The reactor core, steam generators, pressurizer, and all primary coolants are housed within a single integral reactor pressure vessel (RPV), enclosed within a close-fitting cylindrical containment vessel (CV). Both are partially submerged in a dedicated, below-grade, stainless-steel-lined flooded pool that serves as the module’s passive ultimate heat sink. The entire system is factory-fabricated and semi-truck transportable.

The Halo MMR’s safety philosophy centers on passive systems requiring no electrical power, no operator action, and no external water sources to achieve and maintain safe shutdown. Its key safety features include:

Passive Emergency Core Cooling (ECCS): Two independent vent paths automatically cool the core via gravity-driven natural circulation, satisfying single-failure requirements without pumps, diesel generators, or operator action.

Passive Containment Heat Removal: Decay heat transfers passively from the RPV through the containment vessel to the surrounding reactor pool by using conduction and convection needing no power or active components.

Elimination of Large-Break LOCA from the Design Basis: The integral design removes large-bore primary coolant piping eliminating the potential for large-break loss-of-coolant accidents.

10-Year Once-Through Fuel Cycle: Operating on Low-Enriched Uranium Plus (LEU+) fuel at no more than 8.0wt% U-235, the Halo MMR is designed for a 10-year fuel cycle, minimizing operational complexity and long-term fuel costs.

The Halo MMR’s thermal output produces lower decay heat loads, smaller fission product inventories, and reduced source terms, all of which enhance safety margins relative to larger light-water reactor designs and strengthen the technical basis for the proposed PDC exemptions.

Accelerating Momentum Ahead of Public Listing

The NRC submission arrives amid an accelerating period of technical and commercial progress for Hadron. The SEC on April 15, 2026 declared effective the Form S-4 registration statement filed by GigCapital7 Corp (Nasdaq: GIG) in connection with the proposed business combination with Hadron. GigCapital7 has scheduled its special shareholders meeting to approve the business combination for May 7, 2026. The PDC submission directly strengthens the technical credibility and licensing risk reduction profile that will underpin the Company’s capitalization and commercialization roadmap.

Hadron continues to accelerate on multiple fronts — advancing critical subsystem partnerships while simultaneously laying the regulatory foundation for commercial deployment — positioning the Company to lead the next generation of nuclear energy in the United States.

“Submitting the PDC White Paper to the NRC is the most consequential technical milestone in Hadron’s history. We have defined the regulatory framework for the Halo MMR, grounded in established NRC regulatory pathways, and earned early favorable feedback on the planned licensing path from NRC Staff through our pre-application engagement. The combination of our fully passive design, our proven licensing strategy, and our growing commercial pipeline puts Hadron in a position of real strength as we approach the public markets”, stated Samuel Gibson, Founder and CEO of Hadron.

See the full press release here: BusinessWire