Morning Edition · Friday, June 5, 2026
A Privately Built Advanced Reactor Reaches Criticality in Idaho
A privately developed advanced reactor reached a controlled nuclear chain reaction, an early indicator of rising demand for electricity.
The startup Antares achieved initial criticality of its Mark-0 microreactor at Idaho National Laboratory on June 4, the United States Department of Energy announced, describing it as the first privately developed advanced reactor to reach criticality under its pilot program. Criticality is the point at which a reactor sustains a controlled nuclear chain reaction.
It is the first American non-light-water privately developed reactor to reach that point in more than 40 years, the company said. Antares, founded in 2023 and backed by more than $140 million, says it aims to produce electricity from an advanced reactor in 2027, with early deployments to military installations beginning in 2028. The work was carried out with the Department of Energy, the national laboratory and the contractor BWX Technologies.
The milestone has a clear economic cause. Demand for reliable, high-density power to run artificial-intelligence data centers has revived private interest in nuclear technology, and a small, factory-built reactor that can be placed near where the power is used is the type of product buyers want. The Department of Energy described the moment as a revival of the country's nuclear industry.
What this means
The constraint on artificial-intelligence expansion is increasingly electricity, not computer chips, and small modular reactors are the most direct solution to data-center power demand that renewable sources and the existing grid cannot meet on their own. A working private reactor moves nuclear power from a policy goal toward a deployable industrial product, with consequences for energy markets, utilities and the cost of computing.
What to watch
- Antares's path from criticality to actual electricity generation in 2027.
- Power-purchase agreements between reactor developers and data-center operators.
- Regulatory approvals for commercial deployment of advanced microreactors.
Observations to monitor, not financial advice.
Source: The Hindu
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