Summary

Ultra Safe Nuclear Corporation (USNC) was a Seattle, Washington microreactor developer founded to commercialize the Micro Modular Reactor (MMR) — a high-temperature gas-cooled reactor (HTGR) producing 15 MWe / 45 MWt using TRISO fuel in prismatic graphite blocks. The MMR was designed for remote power, industrial heat, and data center applications. USNC also developed the Pylon reactor for space applications.

USNC filed for Chapter 11 bankruptcy in 2024 after failing to secure sufficient commercial capital. In December 2024, NANO Nuclear Energy Inc. won a court-supervised bankruptcy auction, acquiring the MMR and Pylon reactor IP assets for $8.5 million. The acquisition closed March 2025, and NANO Nuclear rebranded the MMR as the KRONOS MMR.

Status as of April 2026: NANO Nuclear is an early-stage public company (NASDAQ: NNE) that acquired USNC’s IP but has limited resources to advance the technology to commercialization. The INL DOME demonstration (Pylon reactor, targeting 2027) is the key near-term milestone. No data center customers have signed binding agreements.

⚑ Key risk: NANO Nuclear is a very small company with limited capital. The $8.5M acquisition price reflects distressed-asset pricing, not commercialized technology. Advancing the KRONOS MMR to commercial deployment requires tens to hundreds of millions in additional capital, regulatory approval, and execution capability that NANO Nuclear has not yet demonstrated.

USNC Background (Pre-Bankruptcy)

Ultra Safe Nuclear Corporation was founded in 2011 by Dr. Francesco Venneri (a leading expert in TRISO fuel and HTGR technology from Los Alamos National Laboratory and Georgia Tech). The company was headquartered in Seattle, Washington, with offices in Oak Ridge, Tennessee, and Atlanta, Georgia.

USNC received early-stage DOE Advanced Reactor Demonstration Program (ARDP) funding, partnered with Ontario Power Generation (OPG) for potential Canadian deployment, and was progressing a Pylon demonstration at the INL DOME facility. However, the company struggled to attract sufficient private capital as the microreactor investment landscape became crowded.

Key USNC people (historical):

  • Francesco Venneri — Founder & CEO: PhD nuclear engineering; former Los Alamos National Laboratory senior scientist; leading expert on TRISO fuel and HTGR technology; co-authored foundational HTGR safety analysis papers
  • Previously held faculty positions at Georgia Tech
  • Departed USNC upon or before bankruptcy proceedings; not confirmed at NANO Nuclear

MMR Technology: What Was / Is the KRONOS MMR

Reactor Design

The original USNC MMR (now KRONOS MMR under NANO Nuclear) is a high-temperature gas-cooled reactor (HTGR) using:

  • Fuel: TRISO fuel compacts embedded in prismatic graphite blocks (same fuel type as Kairos Power and X-energy Xe-100; BWXT is the U.S. TRISO fuel supplier)
  • Coolant: Helium gas (inert, no activation products; clean operation)
  • Moderator: Graphite blocks (slows neutrons to thermal energies)
  • Output: 15 MWe / 45 MWt (thermal-to-electric conversion via Brayton cycle or steam turbine)
  • Operating temperature: ~700–800°C (high temperature enables both high-efficiency electricity generation and process heat applications — hydrogen production, industrial heat)
  • Safety: Passive safety via negative temperature coefficient of reactivity (as temperature rises, fission rate drops); graphite moderator has large thermal mass (slow to heat up, allowing passive cooling)

MMR Energy System

The full MMR “Energy System” (USNC’s commercial product concept) integrated:

  1. One or more MMR reactor modules
  2. A heat storage unit (molten salt buffer for load-following)
  3. Adjacent power conversion and utilization plant

This system was designed to produce up to 45 MWt, scalable by clustering units, with the heat storage buffer enabling time-shifting of electricity output to match data center demand curves.

Pylon Reactor (Space Application)

The Pylon is a separate, smaller reactor design (originally for space and defense applications) that was also acquired by NANO Nuclear. A Pylon demonstration at the INL DOME facility was advancing before USNC’s bankruptcy.

NANO Nuclear Acquisition & KRONOS MMR

NANO Nuclear Energy Inc. (NASDAQ: NNE) is a New York-based advanced nuclear company focused on microreactor commercialization. In late 2024, NANO Nuclear acquired USNC’s IP through the bankruptcy court process:

  • Agreement announced: December 24, 2024
  • Purchase price: $8.5 million (cash; court-approved auction process)
  • Assets acquired: USNC’s patented MMR technology, Pylon space reactor technology, and “worldwide demonstration partnerships” (including INL DOME arrangements)
  • Acquisition closed: March 2025
  • Rebranding: USNC MMR → KRONOS MMR under NANO Nuclear

NANO Nuclear context:

  • NANO Nuclear was founded in 2022 as a next-generation microreactor company
  • Listed on NASDAQ (NNE) as a development-stage company
  • Had its own internal microreactor development programs (ZEUS solid-core reactor; ODIN liquid-cooled reactor) before acquiring USNC’s technology
  • The USNC acquisition added proven TRISO-fueled HTGR technology to NANO’s portfolio — a more mature design than NANO’s internal projects

⚑ Financial position: NANO Nuclear is a development-stage company. As of 2025, revenue is near-zero; the company is funded through equity capital raises. The $8.5M acquisition required significant cash relative to NANO’s balance sheet. Continued development of the KRONOS MMR requires large capital infusions that are not yet secured.

INL DOME Demonstration

Prior to bankruptcy, USNC was advancing the Pylon reactor for a demonstration at the Idaho National Laboratory DOME (Demonstration of Microreactor Experiments) facility. This DOE-funded facility was designed to provide fast-track demonstrations of advanced microreactor designs.

Under NANO Nuclear’s ownership, the DOME demonstration pathway remains intact in principle — the worldwide demonstration partnerships acquired include the INL DOME arrangement. However:

  • The demonstration requires NRC licensing
  • USNC had begun pre-application NRC interactions; NANO Nuclear must continue (or restart) these
  • Target for Pylon demonstration: 2027 (carried over from USNC’s schedule; subject to slippage)

The Pylon demonstration, if achieved, would provide operational data for the underlying HTGR technology platform — supporting the longer-term commercial pathway for the KRONOS MMR.

Data Center Positioning

NANO Nuclear markets the KRONOS MMR for data center and AI applications:

  • High-temperature output (700–800°C) can provide both electricity and high-grade process heat — enabling absorption cooling or hydrogen production co-located with a data center
  • TRISO fuel (shared with Kairos and X-energy) has a stronger supply chain than HALEU (used by Oklo)
  • Modular clustering enables scaling from 15 MWe to 150+ MWe by deploying multiple units on a campus

However, as of April 2026, no data center customers have signed binding agreements with NANO Nuclear for KRONOS MMR power.

Realistic timeline to first commercial deployment: Mid-to-late 2030s, assuming:

  1. NANO secures additional capital (tens to hundreds of millions)
  2. NRC pre-application and COLA process completes (5–8 years typical for first-of-a-kind)
  3. Pylon INL DOME demonstration validates HTGR technology (2027 target, may slip)
  4. Commercial-scale units ordered and manufactured

This timeline is behind Oklo (first criticality 2027–2028), Kairos (first commercial unit 2030), and Radiant Kaleidos (demonstration 2026, production 2028+).

TRISO Fuel Supply Chain Note

The KRONOS MMR uses TRISO fuel — the same fuel type as Kairos Power (FHR) and X-energy (Xe-100). BWXT Technologies is the sole U.S. TRISO fuel manufacturer, with a newly expanded TRISO-X facility in Lynchburg, Virginia. As Kairos and X-energy both scale production, TRISO supply may become constrained. NANO Nuclear (KRONOS MMR) would compete with these larger, better-capitalized developers for TRISO fuel supply contracts.

Regulatory Status (April 2026)

  • USNC had engaged in NRC pre-application interactions under both 10 CFR 50 and the new 10 CFR 53 framework
  • These interactions transferred to NANO Nuclear as part of the acquisition
  • No Combined License Application (COLA) has been submitted
  • The technology is in early pre-licensing phase; several years of NRC engagement required before formal license submission

Key People (NANO Nuclear)

James Walker — CEO, NANO Nuclear Energy

  • Co-founder of NANO Nuclear; nuclear engineering background
  • Previously at various nuclear consulting and technology firms
  • Overseeing KRONOS MMR integration and commercialization strategy

Francesco Venneri — USNC Founder (not confirmed at NANO Nuclear)

  • The technical architect of the original MMR; his involvement at NANO Nuclear post-acquisition is not publicly confirmed
  • ⚑ If Venneri is not involved in NANO Nuclear’s KRONOS MMR development, a significant institutional knowledge gap exists

People — Last Reviewed: 2026-04-25

Watch List

  • Pylon INL DOME demonstration (target 2027): Critical early milestone for HTGR technology validation
  • NANO Nuclear capital raises: Monitor equity raises; insufficient capital = technology stalls
  • COLA submission: No COLA yet; submission date is key indicator of commercialization seriousness
  • Data center customer LOIs: Any announcement of even a nonbinding LOI would signal market traction
  • TRISO fuel supply agreement with BWXT: Securing a supply arrangement would de-risk the fuel path
  • BTM overview: /research/datacenters/behind-meter-power/
  • Westinghouse eVinci (competing microreactor): /research/datacenters/behind-meter-power/westinghouse-evinci/
  • Oklo BTM profile (leading microreactor/SMR for data centers): /research/datacenters/behind-meter-power/oklo-btm/
  • Energy section — nuclear overview: /research/energy/nuclear/