RX, a Korean small modular reactor engineering startup, has raised 10 billion won ($7.5 million) in a pre-Series A bridge round to speed up development of an industrial heat reactor that supplies carbon free heat to industrial sites. The company announced the round on Wednesday 14 October 2026, with the state backed Korea Development Bank, Smilegate and Kiwoom among the investors, and the round qualifies RX for the next phase of a government deep tech programme.
The round and what it unlocks
| Item | Detail |
|---|---|
| Round | 10 billion won ($7.5 million), pre-Series A bridge |
| Named backers | Korea Development Bank (state backed), Smilegate, Kiwoom |
| Purpose | Speed up development of a reactor that supplies carbon free heat to industrial sites |
| Effect | Qualifies the company for the next phase of a government deep tech programme |
The programme is the Ministry of SMEs and Startups’ Deep Tech Challenge Project. In July 2026 RX was selected as a finalist and as the lead organisation in the energy sector, and selected organisations can receive research and development funding of up to 20 billion won after preliminary research and stage evaluations. At the exchange rate implied by the 10 billion won and $7.5 million figures, 20 billion won is about $15 million, so the private bridge round equals half of the maximum public funding it opens the way to.
The structure of the public funding is worth reading closely. The up to 20 billion won follows preliminary research and stage evaluations, so it is a ceiling that is reached in steps and not a commitment on day one. That makes the private round useful in two ways: it funds work between evaluations, and it shows evaluators that outside investors are willing to put money behind the same plan.
A reactor aimed at heat, not only power
RX is developing a light water cooled small modular reactor for heat supply. The Korea District Heating Corporation joined the programme as the demand side company, and Mirae Asset Venture Investment is its funding and commercialisation partner, so the project has a heat customer and a financing route named from the start. The company’s chief executive, Lee Kang-heon, said industrial heat accounts for a significant portion of global final energy consumption and remains highly dependent on fossil fuels, and that the company aims to decarbonise industrial heat and district heating with a light water reactor that is both economically viable and safe.
The company is a researcher founded spin off from the SMR Design Division of the Korea Atomic Energy Research Institute and bases its heat reactor on proven light water technology. A venture investor reported in January that the research institute had selected RX as one of three nuclear deep tech companies for its core company support, which includes use of research facilities, staff secondment and global marketing, and that RX’s engineering base includes a spiral steam generator design platform.
What a bridge round signals
A pre-Series A bridge sits between early seed funding and a larger priced round, and here it also has a specific job: to meet the condition for the next phase of the public programme. Pairing a state backed bank, a games developer and a brokerage with a ministry programme and a district heating operator widens the circle around a company that is still early. Smilegate is among domestic investors that have been putting money into local startups.
What remains to be shown
The material available gives no thermal power for the reactor, no output temperature, no site, no schedule and no licensing path. Those are the numbers that determine which industrial heat users the reactor could serve, and they are the ones to look for as the programme’s evaluation stages proceed. The dated facts are the round on 14 October 2026, the July 2026 selection and the next phase of the programme that the round now allows. For how reactor licensing is progressing in another market, see the three NRC filings covering seven reactors. Sources: report of the RX funding round, 14 October 2026 (headline and summary available), and the July 2026 announcement of RX’s Deep Tech Challenge selection.
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