A witness to atomic history

“At those times, jobs were jobs,” said Petry, who as a laboratory assistant helped build the 20-foot-tall reactor known as Chicago Pile-1. “But they didn’t say we were going to be building an atomic pile.”

As the University of Chicago commemorates the 75th anniversary of the first nuclear reaction, Petry shared his memories of working on the classified Metallurgical Laboratory project. That was the codename for the activity at UChicago, where the world’s leading scientists were racing to achieve the chain reaction as a step toward developing nuclear weapons before Nazi Germany.

All these years later, Petry said he still struggles to grasp the magnitude of the project he worked on and how it changed the world. His memories are largely of the physical work that he and others carried out under the west stands of Stagg Field, and his life as a South Side teenager who rode a street car to UChicago from his parents’ Englewood home.

“He was a kid that did a job. He worked on this pile that’s written in the history books,” said Laura Dowling, the youngest of Petry’s four children. “A lot of people have their one claim to fame, and that’s our dad’s.”

‘You didn’t question too much’

Petry first got involved with the project when a recruiter visited his Tilden Technical High School. After he graduated in January 1942, the 17-year-old signed on for a $94 monthly salary, along with his twin brother Arthur.

He became a self-described “go-fer” or “peon” for the UChicago project, one of 30 or so young men hired as laborers. Day and night, they stacked the tons of wood that would support the atomic pile; cut and moved the 45,000 graphite blocks that formed its lattice structure; and used a hydraulic press to turn uranium powder into thousands of baseball-sized spheres that formed part of the reactor’s fuel.

Petry vividly recalls riding a streetcar downtown to pick up a container that he carried in his pocket back to the University. A doctor found Petry’s blood cell count was going down, which Petry attributed to the “radioactive material” he had been delivering. When he returned weeks later, he instead drove downtown in a station wagon outfitted with a large lead container—a much better carrying case than his pocket.

Petry’s next task ended up being the most important of all, working in the cold, unheated concrete squash court to build the pile. Using woodworking machinery, he and a crew of men planed blocks of graphite into 4-foot-long rectangles, then drilled holes in them to hold thousands of uranium pellets. Those pieces were then slid down 2-foot-by-12-foot boards about 20 feet down below to be used in the pile.

Fermi’s calculations indicated that the lattice of graphite bricks and uranium that made up the 20-foot-tall, beehive-shaped structure known as Chicago Pile-1 would create a nuclear chain reaction.

Fermi was a constant presence around the piles, recalled Petry, who remembered him as a “quiet, little Italian guy” who was quite collegial and always carrying a slide rule. “It was more or less ‘family style’: Come and help me out.”

All along, Petry said he never asked the intended use of all the construction work. “A lot of people worked there and left without any knowledge of what was going on,” he said. “You didn’t question too much.”

That included when Petry saw workers jackhammering doorways into the West Stands of Stagg large enough for people to walk through. “If the pile went critical, and they couldn’t control it,” Petry recalled, “they said, ‘Get out through those things and head for Indiana.’”  

‘1, 2, 3, and it was over with’

Wednesday, Dec. 2, 1942 started as a typical day at work, Petry remembered. But once inside Stagg Field, he saw a large number of dignitaries and scientists gathered in the balcony of the squash court. “When all these people came in,” he said, “you begin to wonder, ‘Hey, what’s going on?’

The night before, workers had finished assembling the 57th layer of Chicago-Pile 1—the 15th straight day of non-stop work in building the reactor—and all indications were that it was ready for its critical test. Petry remembers gathering with others in the balcony, while Fermi was next to the pile conducting the experiment.

History was made at 3:25 p.m., with the splitting of a single uranium nucleus into a sustained chain reaction.

“It worked out perfectly. It was a simple slide rule experiment—1, 2, 3 and it was over with,” Petry recalled. “Fermi said, ‘That’s it,’ and everyone rejoiced.”

Project scientist Eugene Wigner presented Fermi with the bottle of Chianti and some paper cups to toast the achievement. It was a solemn moment, Petry recalled, with those in the room signing the bottle’s straw wrapper to signify they were present for the reaction.

“Surprisingly, they just asked you to sign it. You knew these people, but you considered them workers alongside of you,” Petry said. “They didn’t feel like they were above you.”

‘The Baby of CP-1’

Petry left UChicago soon after, tired of the back-and-forth to work. He subsequently turned down jobs in the suburban Argonne forest preserve, where nuclear piles were tested; and an opportunity in Los Alamos, N.M., where nuclear bombs were assembled and tested. Instead, he worked a number of jobs in support of the war effort: He sailed on the USS Youngstown, an ore freighter in the Great Lakes; worked at the Dodge Chrysler plant, making engines for C-47 war planes; and served as a tool-and-die maker at the Pullman plant. In the years that followed, Petry worked in manufacturing and taught shop for 17 years in the Chicago Public Schools.

But his contributions to the war effort did not go unnoticed by the University and the U.S. government. Petry attended UChicago’s 20th anniversary celebration of the first chain reaction in 1962, and he was part of the University contingent invited to Washington, D.C. to meet President John F. Kennedy in the Rose Garden.

In a letter from November 1962 from Washington, D.C., Petry wrote his wife Adeline about the warm reception from his old colleagues, who reminded him that he was the youngest of the group. “The fellows are kidding me as ‘the Baby of CP-1’ … It’s terrific the attention a guy like me is getting from all these fine educated men. It sure makes you feel good.”

‘It was just a job’

On a recent fall afternoon in his suburban Orland Park home, Petry relaxed in a recliner, talking about the project, his career and his family. Thumbing through a red binder containing photos, news clippings, awards and certificates from the era, he reminisced about the work at the University of Chicago and the friends he made on the atomic project, including Jerry Pawlicki, a former UChicago graduate student who died in 2013 at the age of 91.

According to Argonne National Laboratory records, more than a quarter of the 49 scientists who were present at the critical experiment on Dec. 2, 1942 lived into their 90s. Five passed away in the past five years, most recently Warren Nyer in February 2016 at the age of 94, leaving Petry as the only known witness to history—a distinction of which Petry was unaware.

For the most part, Petry has kept his story out of public view— much like the secret experiment under the west stands of Stagg Field and the Chianti bottle stored in a gray cardboard box at the National Archives of Chicago.

“My neighbors don’t know that I ever worked on the project. I don’t go around sticking my chest out,” Petry said. “I just went ahead and lived a normal life and didn’t think about half this stuff.”

“It was a way of life. It was just a job.”