The “suicide squad” stood guard with cadmium solution, ready to prevent the experiment from getting out of control. One man held an ax, in case he needed to cut the safety rope. Armed with their safety rods, other men waited behind two concrete walls.

The site was Stagg Athletic Field at the University of Chicago. The year was 1942. The center of attention was a massive apparatus that would be used to spark the first controlled nuclear chain reaction.

The chain reaction was a success. The suicide squad — prepared to sacrifice their lives if necessary to contain the reaction — was never called upon.

It would be another three years before the world knew the scope of that success, which led the United States to use the first atomic bomb in warfare. The explosion in Hiroshima, Japan, killed 66,000 people and left 69,000 others injured.

Scholars have debated the morality of the Hiroshima attack for a half-century. It’s an issue that has prompted sharp divisions. It’s an issue that Iowa State had a hand in.

This year marks the 50th anniversary of the decision to stop producing the uranium that fueled the only nuclear attack in human history. That uranium was produced right here on Iowa State soil.

Dr. Frank Spedding of Iowa State College, ISU’s name at the time, looked on with his colleagues in Chicago as they witnessed the first-ever self-sustaining nuclear chain reaction.

Iowa State College contributed two tons of uranium metal for the University of Chicago’s chain reaction. Iowa State’s team was led by physical chemist Spedding and metallurgist Harley Wilhelm. In 1942, the two men began supervising the chemistry division of the federal government’s atomic research work at Iowa State.

Wilhelm discovered how to reduce uranium tetraflouride to produce pure uranium metal. He took his product to the University of Chicago, where the federal Metallurgical Project was located. The Ames Project was then designated as the site to produce 100 pounds of uranium per day.

In all, 2 million pounds of uranium was produced here.

After the success in Chicago, the Ames Project ran an industrial-type production plant to become part of the Manhattan Project, the name of the overall nuclear project.

Working for Wilhelm, Wayne Keller was in charge of the uranium metal preparation here on campus. Keller hired undergraduate workers to execute the processing of the metal. David Peterson, a now retired metallurgical professor at Iowa State, was one of those undergraduate students.

“I had just turned 20-years old and was a senior here with a chemistry major. At the end of the fall quarter, I’d run out of the money that I’d saved up from the summer. I was offered a job that was supposed to be a big wartime project,” he said.

Before beginning his work, Peterson and other crew members had to change into uniforms: cotton twill shirts, pants and caps. When their shift was finished, they had to shower to wash off any uranium particles.

When the crew members got home after a long day’s (or night’s) work, they were still not free from all work obligations. Because of the secrecy of the job, they were not allowed to talk about their work, even to family members.

“Information was compartmentalized to a considerable extent by a need-to-know basis,” Peterson said. “There was an extremely high degree of secrecy because this was in the middle of World War II, and at that time it wasn’t entirely clear just how the war was going to go.

“When I started work on Dec. 7, 1942, I was put to work immediately, but I wasn’t allowed to know what we were working on officially until I had been given a background check.”

But Peterson figured out on his own what he was working on. He was experimenting with a green powder, calcium, to help produce a metal with a higher density than mercury — uranium. “I wasn’t supposed to know that [about uranium], but I observed and put things together. But I kept my mouth shut,” he said.

Peterson’s mannerisms today suggest he is someone who doesn’t have much difficulty putting two and two together. On his yellow legal pad, his black pen jots down the details of what he says. As he talks, he constantly illustrates his point with symbols, graphs and words. He spells out names and underlines important points.

Before signing on with the Ames Project, Peterson had read about the possibility of constructing such a powerful explosive as the atomic bomb.

“Probably going back to ’39 or ’40, there had been conjecture that there might possibly be some way of converting matter to energy,” he said.

Peterson, like all Manhattan Project workers, had to receive local approval from the state to assure good community and university standing, called a P-approval. Everyone from the assistants on up in the hierarchy of project employees also had to receive Q-clearance, a more in-depth background check investigated by the U.S. Army and the FBI.

Peterson said if he wanted to discuss his work with anyone, that person needed to have Q-clearance. Otherwise, disclosing information could get a worker fired, drafted into the war’s front lines and charged for breaches of security.

After the workers proceeded through P-approval and Q-clearance, they were given a little more information about the technicalities of their work. But, as Peterson said, “We were never told everything.”

He said information regarding schedules and timetables — information that could reveal the United States’ progress in developing the atomic bomb — was especially kept secret.

Despite the government’s assumption of worker ignorance about the bomb, Peterson admits he did know — at least potentially — what his would could lead to. He knew he could be working on — directly or indirectly — one of the most lethal killing devices ever created.

Yet he stayed on. In doing so, Peterson said he made the only logical choice. He said he weighed the options, giving particular weight to Germany’s potential atomic discoveries.

Still, it was a decision that demanded reflection, he said, a decision with an impact he still remembers today — a half-century later.

— Some information for this report was provided by the December 1992 edition of the Insider, a newsletter for the employees of Ames Laboratory.