What do we really know about the reactor?

The technical specifications of the nuclear reactor Oklo is building in Lockhart, are still unconfirmed and unknown at time of writing.

The only information shared with the public so far are corporate press releases and what might be inferred from Atomic Alchemy’s past NRC documents. Everything below is based on that assumption – which may change as more is revealed about this project!

The Lockhart Groves facility is believed to be a VIPR [link] [link] reactor, technology purchased by Oklo in their recent acquisition of Atomic Alchemy in 2025.

The closest technical specifications for a VIPR reactor publicly available on the NRC website are found here: [https://www.nrc.gov/docs/ML2525/ML25255A220.pdf]. It most likely describes a previous Atomic Alchemy project involving the VIPR design which was cancelled, known as Meitner-1. It shares the same docket number and publication date with other Meitner-1 documents. While this docket cannot be assumed to be the same reactor as Groves, the open source information on this project provides a useful framework for exploring the potential impacts the Groves reactor may have, and what kinds of specific questions might hold its owner Oklo accountable to the people of Lockhart and central Texas.

It is unknown whether these are the same technical specifications as the Groves facility, especially in light of the proprietary withholding granted to Oklo by the NRC in February 2026.

With that context, a summary of the VIPR specifications found reveal:

• A maximum thermal output power of 16.80 MWt (thermal megawatts of heat)
• A shutdown or low power output of 500 kWt (thermal kilowatts of heat)

Watts are a measure of energy transfer. It can be confusing to see “watts” because electrical power transfer is also measured in watts. The energy transfer in this context is heat energy, produced as a byproduct of the nuclear reaction used to bombard various materials with neutrons produced by the reactor. That is how various radioactive isotopes are produced for medical and other uses.

This heat must be removed by the water cooling system. If it is not removed, eventually the reactor overheats must be shutdown immediately, in an emergency event called SCRAM. If that fails to happen – perhaps a moving part gets stuck – the core literally melts, the reaction runs uncontrolled and integrity of the site may be breached. That is essentially what happened at Chornobyl and Fukishima.

What kind of fuel is used?

The cancelled Meitner-1 VIPR reactor description on the NRC website [https://www.nrc.gov/docs/ML2525/ML25255A207.pdf] provides a potential clue.

This document describes 4 reactors, which is consistent with Meitner-1. Lockhart is the “pilot program” described in this article, the successor to that cancelled project, with similar power output (up to 16.8 MWt in section 4.6.1) which uses pellets of Low-Enriched Uranium (LEU) fuel.

This is confirmed in Oklo’s recent response to some of our questions.