BONUS Latin American power plant

The Boiling Nuclear Superheater (BONUS) was the world’s eighth nuclear power plant and the first to be built in Latin America. A museum in the facility tells the story of the BONUS as a combined effort of the U.S. Atomic Energy Commission and Puerto Rico Water Resources Authority.

Domes Beach in Rincón, Puerto Rico, widely known for hosting several international surfing competitions every year, is considered one of the most popular surfing beaches in the world. But beyond the waves, there’s more than immediately meets the eye in this celebrated place. Peeking out just above the shore’s tree line is the namesake dome itself, a prototype nuclear power plant: the eighth constructed in the world, and the first in Latin America. Called the Boiling Nuclear Superheater (BONUS) reactor, the dome is a U.S. Department of Energy (DOE) Legacy Management Office (LM) site.

Although the nearby sunny beaches are synonymous with Puerto Rican culture and lifestyle, few people understand this area’s important role in the territory’s history. This Hispanic Heritage Month, LM is helping to highlight the history of one of its most picturesque sites.

“Puerto Rico is known for its stunning geographical landscape and rich culture – the beaches and mountains, the food, the music, and the arts,” said Cliff Carpenter, LM project director and site manager at BONUS. “But Puerto Rico has also played a vital part in American non-military history, and its involvement is sometimes overlooked. During Hispanic Heritage Month and beyond, we’re hoping to celebrate these contributions and illuminate the diverse history of the island.”

LM Director Carmelo Melendez added, “In the 1980s, while living on the Island and subsequently attending the University of Puerto Rico’s Engineering School at Mayaquez, I did not realize there was a decommissioned nuclear reactor just 45 minutes away from the school! I do remember that one of my best professors, Dr. Fernando Pla-Barby, was a mechanical engineer who had worked at BONUS with the Puerto Rico Electric Power Authority; I just thought it was concerning wave energy not nuclear energy!”

Throughout Hispanic Heritage Month, institutions like the National Archives and Presidential Libraries showcase historic documents, films and other exhibits that highlight Hispanic culture and achievements. At BONUS, this legacy is close to home – and displayed at the Modesto Iriarte Technological Museum.

The museum, named for Puerto Rican scientist and nuclear engineering pioneer Dr. Modesto Iriarte Beauchamp, is located inside the domed building. It tells the story of the BONUS as a combined effort of the U.S. Atomic Energy Commission and Puerto Rico Water Resources Authority.

The plant was in operation from 1965 to 1968 and became a training camp for hundreds of Latin American scientists. It played an important part in bridging the political and social projects outlined in President John F. Kennedy's Alliance for Progress, which bolstered economic activity and progress between the United States and Latin America. Today, the museum is listed on the National Register of Historic Places. LM supports Puerto Rico Electric Power Authority (PREPA) in maintaining the plant and its museum.

“Although in 2016 when I came to LM and talked to the site manager and fully understood how unique of a site this was, nothing prepared me for the first time opening the hatch and walking into the containment area,” Melendez said. “PREPA and other stakeholders had done an outstanding job preserving the site from a surveillance and maintenance standpoint, as well as for educational and beneficial reuse purposes.”

Carmelo BONUS tour

LM Director Carmelo Melendez

As explained to Melendez by the American Nuclear Society, he said “the nuclear plant design was somewhat unique in that not just the nuclear steam supply system was inside the containment; instead, the entire power plant, including the control room, was inside the 190-foot-diameter structure. So, unlike other decommissioned reactors where everything had been removed from the containment structure and support buildings, like in the Piqua decommissioned reactor in Ohio, BONUS looks like the reactor’s operators just walked out for a break,” he said. “It’s like walking back in time.”

Exhibits throughout the museum dig into the island’s Spanish Colonial, American, and Hispanic history, aiming to deepen visitors’ understanding and appreciation of Puerto Rico’s history. Each sheds light on how testing and discoveries at BONUS pioneered the development of electric power and nuclear energy in the United States.

“The breadth of the museum exhibits speaks to the multifaceted history of the land and the people who have lived on it,” Carpenter said. “There’s something for everyone there, whether you’re a history buff or curious to know more about the first Indigenous people on the island – I think that’s why local visitors feel such a connection to the museum.”

The museum serves the local community in a variety of capacities, including ongoing outreach and education focused on the area’s endangered species. The site is staffed with bilingual employees, features signage in English and Spanish, and receives visitors from six nearby public schools in Rincón. The museum also partners with institutions of higher education such as the University of Puerto Rico and the Ana G. Méndez University system to offer research materials and resources to students.

“At the museum, we’re constantly seeking out new ways to engage the community and widen exposure to the education it provides,” Carpenter said. “Hispanic Heritage Month calls attention to the work we do year-round to elevate Puerto Rico’s storied past and highlight its many contributions to United States history.”

Through the Modesto Iriarte Technological Museum, LM continues in its mission to preserve, protect, and make accessible legacy records and information that highlights the storied history of the territory of Puerto Rico – and the contributions of its people.

“DOE and PREPA collaborate well together in fulfilling our long-term stewardship responsibilities,” Melendez said. “I look forward to the day we can contribute to enacting the vision of having the historical BONUS site open to the public on a regular basis.”