Aalo and Antares progress on Reactor Pilot Program

Two participants in the Department of Energy's Reactor Pilot Programhave recently announced significant milestones on their associated reactor projects. Aalo Atomics successfully completed its final design review (FDR), and Antares Nuclear has received DOE approval of its preliminary documented safety analysis (PDSA).

Antares analysis: According to Antares, the PDSA formally approved by the DOE defines the preliminary safety basis for its reactor, facility, and planned operations. DOE approval validates the company's safety case while also establishing a pathway to final acceptance.

Bob Boston, manager at the DOE's Idaho Operations Office, said that other DOE offices and the Nuclear Regulatory Commission assisted in reaching the approval, which centered on the Mark-0, Antares's first demonstration reactor.

In its January 26 announcement of the milestone, Antares also communicated some new details about its plans for the project. Mark-0 will be tested at Idaho National Laboratory's Building 793, which has been renamed the Reactors and Critical Experiments Facility. This building once housed ML-1, the U.S. Army's first mobile reactor.

The company reaffirmed that it is still on track to run a zero-power criticality test before July 4. Antares is aiming to build and test their next demonstration reactor in 2027.

Aalo review: On January 22, Aalo announced that it had completed its FDR with 40 independent DOE and NRC reviewers after a 16-hour session spread over two days. Aside from the company's reactor design, the FDR also covered plans for plant operations, security, and other administrative considerations.

Austin Anthis, Aalo's principal mechatronics engineer, said about the FDR, "We got thorough, constructive feedback from our reviewers. The feedback helps us iterate fast: It sharpens our design, improves our regulatory submittals, and builds confidence as we ramp up fabrication."

He added that Aalo is still on track to reach criticality by July 4. For the company, the next step to reach that goal is to incorporate the feedback it received at the FDR into a final documented safety analysis and readiness assessment. Once approved-according to Aalo-all regulatory hurdles necessary to turn on the reactor will be cleared.

NRC tie-in: The involvement of the NRC in the review processes for both Antares and Aalo aligns with recent developments at the regulator. Earlier this month, the NRC issued new staff guidanceto establish expectations for working with reactor vendors leveraging DOE/Department of Defense authorization (such as the participants in the Reactor Pilot Program). That guidance emphasized that NRC observers can be invited to participate throughout the authorization process. Those observers will then directly support a vendor's NRC licensing goals beyond its initial DOE/DOD project.