America's only fatal reactor accident happened in Idaho 61 years ago; prior nuclear bomb test likely killed actors in Utah - East Idaho News

America’s only fatal reactor accident happened in Idaho 61 years ago; prior nuclear bomb test likely killed actors in Utah

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SL-1, an experimental boiling water reactor on the Nuclear Reactor Testing Site began producing electricity in 1958. Its purpose was to conduct research for the U.S. Army’s efforts to develop small reactors and in 1961, it exploded. Another nuclear accident occurred eight years prior near St. George, Utah. Watch the interview above to learn more. | Photo courtesy Joel Hiller

IDAHO FALLS – If 26-year-old Navy Seabee Richard Legg and Army Specialists John Byrnes, 22, and Richard McKinley, 27, had known what was going to happen when they arrived at SL-1 for the first working day of the New Year, they might still be around to talk about it.

It was Jan. 3, 1961, and America was at the height of the Cold War. The launch of Sputnik three years prior had ushered in a new era of scientific discovery while intensifying relations between the warring nations. Scientists were searching for better ways to harness the atom for nuclear power generation and for use as weapons.

Idaho was one of the places where the sole focus of nuclear research and testing was — and remains today — on energy generation and not on weapons development.

SL-1, an experimental boiling water reactor designed to conduct research for the U.S. Army, was one of several reactors on the National Reactor Testing Station, the forerunner to the Idaho National Laboratory. INL officials say SL-1 was one of 52 test reactors that had been built at the site to learn about nuclear energy for the purpose of producing energy.

Unfortunately, the research wasn’t always without cost as was the case at SL-1.

On that fateful day about 40 miles outside Idaho Falls, the three military men arrived around 9 p.m. and prepared to restart the reactor after an 11-day maintenance shutdown.

Curtis Smith, an INL spokesman, tells restarting it was a gradual process that had multiple steps in getting it to operate at full power.

“At some point, (Byrnes pulled) the main control rod. (It) got moved too fast and too far (out of the reactor’s core),” Smith says.

This caused SL-1 to quickly surpass full operation, setting off a chain reaction that resulted in an explosion. The blast slammed Byrnes against a concrete wall and impaled Legg against the ceiling. Both men died instantly, according to historical records from the INL. McKinley was initially knocked unconscious.

Moments after the fallout, an alarm sounded and response teams arrived within minutes.

“First responders initially thought nothing was wrong because the reactor building’s exterior looked normal, and there had been two false alarms tripped earlier in the day. However, upon entering the building their radiation detectors immediately indicated high radiation levels. The rescuers rotated trips inside at 65-second intervals to reduce risks to their own safety,” according to a historical fact sheet provided by the INL.

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Mockup of the SL-1 reactor top. Analysts tried to determine where the three cadremen were standing at the moment of the accident. | Joel Hiller

The bodies of Legg and Byrnes, which were highly radioactive at that point, were found lying among the debris.

Crews attended to McKinley’s wounds but he ultimately died from his injuries hours later while waiting in an ambulance for a doctor to arrive.

An investigation team later determined the operator was trying to reconnect the control rod, which had a history of sticking to its drive mechanism. The rod was pulled more than 2 feet out of the reactor, more than six times the 4-inch maximum.

Radiation contamination was mostly confined to the inside of the building, which meant there was no widespread impact. Only the men who were killed and those involved in the rescue attempt were exposed. No one involved in the recovery or investigation died from the contamination.

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The cleanup effort lasted between 10 and 18 months and SL-1 was eventually decommissioned and dismantled. The men who died in the explosion were buried in lead-lined caskets. Today, the SL-1 explosion is remembered as the only fatal nuclear reactor accident in U.S. history.

“While there have been what are considered industrial fatalities at other generating stations, these are the only U.S. fatalities caused by the process of making nuclear energy,” a historical fact sheet says.

The details of the accident were widely reported at the time. Local media outlets followed the story for weeks. In 2003, a journalist from Colorado Springs published a book about it, which is available online.

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The enclosed stairway from the SL-1 support building to the operating floor of the reactor silo. | Joel Hiller

Operation Upshot-Knothole in Nevada

Eight years prior to SL-1, the Atomic Energy Commission conducted another type of nuclear test about 500 miles to the south.

In 1950, President Harry Truman designated 1,350-square-miles of desert landscape in southern Nevada as a site for nuclear weapons testing. This testing was completely unrelated to the nuclear energy research in Idaho.

The Nevada site was 65 miles north of Las Vegas and 144 miles west of St. George, Utah. Nuclear weapons tests had been conducted on the Marshall Islands previously but U.S. leaders wanted to continue testing on American soil because it was more cost-effective.

Eleven atomic bomb detonations took place on the Nevada Test Site between March and June 1953, which is known as Operation Upshot-Knothole. Most of these detonations resulted in very little damage, but a warhead known as Harry, was “designed to do far more damage while giving off less harmful side effects,” Author Ryan Uytdewilligen says in a new book detailing what happened.

But that’s not how things played out.

“When the bomb was detonated, a yield of 32 kilotonnes was produced — almost double what scientists were anticipating. For reference, the bomb dropped on Hiroshima, (Japan) was only 13 kilotonnes, not even half of Harry,” Uytdewilligen writes.

In a conversation with, Uytdewilligen says the detonation occurred during a wind storm, which blew a lot of radioactive debris towards St. George. It made a lot of people sick at the time and even killed some sheep.

“They were briefly concerned and they were told not to worry and that was that. They didn’t raise much of a stink trying to fight for their rights or question their safety until much later,” says Uytdewilligen.

About a year later, St. George was selected as the shooting location for a Hollywood movie called “The Conqueror,” based on the life of Mongolian Emperor Genghis Khan. The filmmakers were enamored with the area’s red soil because it resembled the Gobi Desert where Khan lived.

Despite widespread news of the fallout, production moved forward with little concern from the cast and crew. Locals were excited at the prospect of having movie stars in their hometown, which was likely a distraction from the worries of the day.

“When they shipped everyone out there and established the sets, the crew started hearing from the locals about the nuclear tests and witnessing what happened,” says Uytdewilligen. “Suspicions were raised at that point and it was John Wayne (the star of the film) who said it would be unAmerican to step away from it now.”

Wayne famously had a Geiger counter on set, which indicated radiation levels were off the charts. He wrote it off, saying “it must be broken,” and moved on.

“The Conqueror” was released in Feb. 1956 and in the ensuing years, many of the people involved died of cancer. Uytdewilligen says it’s difficult to say whether their exposure to radiation during the film’s production was directly responsible because much of the crew, including John Wayne, were heavy smokers. Regardless of the cause, Uytdewilligen says contamination definitely played a role.

More than 60,000 people in the St. George area are reported to have been impacted by the fallout. A federal program set to expire in July provides compensation for victims and their families.

Nuclear energy and weapons testing in the 21st century

The world of nuclear testing looks much different today than it did in days prior. There’s a much greater emphasis on safety, which evolutions in technology have helped improve.

When it comes to nuclear reactors, Smith says they are smaller and have better control systems with digital readouts and backup safety features to prevent accidents due to human error. The U.S. mentality has also shifted from global nuclear dominance to solving problems related to greenhouse gas emissions and climate change.

Nuclear weapons testing changed significantly when Congress disbanded and reorganized the Atomic Energy Commission in the 1970s. The fall of the Soviet Union in the 1980s signified the end of the Cold War and a treaty signed by a majority of countries in the early 1990s led to the demise of nuclear arms testing around the globe.

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“The U.S. has not ratified that yet … so it could start doing nuclear tests at any moment,” says Uytdewilligen, noting North Korea’s recent missile tests and current tensions with the U.S. “It’s an interesting continuation to the Cold War that we have more countries than ever with nuclear capabilities. It’s definitely not as active as it was in the ’50s but it’s just as prevalent.”