Idaho Cleanup Project crews safely demolished the S1W naval reactor prototype building using explosives, ahead of schedule and under budget. The milestone marks progress in reducing the legacy footprint at the Idaho National Laboratory Site. The project was overseen by the DOE and IEC, with plans to complete remaining debris removal this fall. The S1W played a crucial role in developing the USS Nautilus and training nuclear submarine operators.
U.S. Department of Energy photo
Idaho Cleanup Project demolition crews use targeted explosive charges to bring down the Submarine 1st Generation Westinghouse reactor prototype plant building on May 31, 2025.
Idaho Cleanup Project (ICP) crews completed the demolition of the Submarine 1st Generation Westinghouse (S1W) naval reactor prototype plant on May 31, 2025, safely using explosives to carry out this key milestone, according to the U.S. Department of Energy (DOE)
The effort, overseen by the DOE Office of Environmental Management (EM) and ICP contractor Idaho Environmental Coalition (IEC), marks significant progress in reducing the legacy footprint at the Naval Reactors Facility (NRF) at the Idaho National Laboratory Site in Idaho Falls, Idaho.
The carefully planned demolition followed extensive efforts that began in 2022 to safely remove contaminated and hazardous materials from the historic building. Earlier this year, ICP crews also removed the S1W's defueled reactor vessel, disposing of it in a nearby onsite disposal facility in accordance with federal and state regulations.
The S1W demolition project has maintained an accelerated pace, completing work three months ahead of schedule and about $16 million under budget.
Mike Swartz, IEC's senior manager over demolition projects, commended the effort of the employees who worked hard on this significant accomplishment.
"This milestone represents the professionalism and dedication from every member of our team," said Swartz. "Their ability to safely and efficiently execute complex work like this demolition will allow us to successfully complete our mission at NRF."
While EM and IEC are responsible for managing the demolition of the S1W and other historic reactor vessel prototypes at NRF, acting ICP Manager Nick Balsmeier recognizes the importance of an effective partnership with the U.S. Naval Nuclear Propulsion Program.
"I am incredibly proud of IEC and their team, and grateful for support from our partners at Naval Reactors," said Balsmeier. "It is the collective effort that will allow DOE to continue meeting our cleanup commitments and enable a strong future at the Idaho National Laboratory Site."
In the coming months, crews will remove the remaining debris from the S1W plant demolition project, recycling material to the extent practicable. Crews anticipate completing the remaining work associated with the demolition project this fall.
The S1W is a defueled naval nuclear propulsion plant prototype and supported the development of the USS Nautilus, which was launched in 1955 as the world's first operational nuclear-powered submarine. S1W was built to simulate a submarine hull, with a nuclear reactor compartment surrounded by more than 300,000 gal. of water to mimic ocean-like conditions.
David Honabach, a former student and staff instructor at the S1W, reflected on the significant role the S1W and NRF played in proving a new technology that propelled the development of the U.S. nuclear navy fleet.
"When you go all the way back…you can look at the challenges that we had. And you could look at where we were as a nation and what we were trying to solve. For S1W…we were really trying to convince the military and the nation, as nuclear power technology was becoming available, how to convert from diesel to nuclear power, proving that that was capable, proving that it could fit into a submarine hull," said Honabach.
In addition to providing critical research and development, S1W served as a training ground for thousands of prospective students. Honabach provided insight into training and how the S1W developed a skilled, competent force of nuclear submarine operators.
"From the Navy side, it was really about the training of students. We recognized that there was a significant number of students that went before us. And we recognized the importance of being trained and qualified on a land-based prototype before we actually went, in our case, to a submarine," he said. "We understood that that was absolutely critical in order to obtain our submarine warfare qualifications and to be able to be a productive crew member once you got to your first submarine."
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