Holtec SMR-300 testing facility progresses at INL

September 1, 2026, 11:54AMNuclear News
The HI-TEST facility at Idaho National Laboratory. (Photo: Holtec)

Holtec has announced it is advancing with component fabrication for a testing facility at Idaho National Laboratory that it will use to quantify performance margins of its SMR-300 pressurized water reactor. The facility, dubbed HI-TEST, will use test loops to replicate accident scenarios and steam generator behavior, aiming also to support future power uprating for SMR-300 units.

According to an press release Holtec issued last week, the HI-TEST facility will investigate SMR-300 design margins under both steady-state and transient conditions to corroborate the company’s simulations of the plant’s generation capacity, resilience, and operability.

Piyush Sabharwall, a scientist at INL, said in a LinkedIn post that the project is on track to start testing in 2027.

Deployment details: Holtec has several planned sites for SMR-300s, its 300-MWe (1050-MWt) reactor that is designed for a lifetime of 80 years using standard PWR fuel.

The company has been leading the restart of the existing 777-MWe PWR at the Palisades site in western Michigan, and plans now include constructing two SMR-300s on site. Holtec had initially expected to complete the reactor restart by the end of 2025, but work is ongoing. On August 30 the company announced it has started the process of loading fuel into the plant’s reactor vessel.

Meanwhile, Holtec has been decommissioning the Oyster Creek nuclear power plant site since 2019 and has announced plans to deploy four SMR-300s there.

In context: INL is home to the National Reactor Innovation Center and its Nuclear Energy Launch Pad, as well as the recently opened Demonstration of Microreactor Experiments (DOME) facility.

Several companies in the Launch Pad and its predecessor, the Reactor Pilot Program, recently completed zero-power fueled criticality tests of their reactor designs on the INL campus, including Aalo Atomics, Antares, and Deployable Energy. Radiant Industries is first in line for testing a microreactor at DOME.

These companies are largely pursuing more novel reactor concepts with, for example, TRISO fuel, gas or liquid metal cooling, and power levels at microreactor scales. Holtec’s SMR-300 is a more traditional PWR and thus has had the benefit of extensive data from operating PWRs, which make up roughly 70 percent of the current operating nuclear fleet globally.

Several other companies are pursuing PWRs at SMR scales, including Westinghouse with its AP300, based on the company’s AP1000.


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