The U.S. government secretly allowed radiation from a damaged reactor to be released into air over the San Fernando and Simi valleys in the wake of a major nuclear meltdown in Southern California more than 50 years ago — fallout that nearby residents contend continues to cause serious health consequences and, in some cases, death.

LA's Nuclear Secret: Timelines, Documents, FAQ

Those are the findings of a yearlong NBC4 I-Team investigation into "Area Four," which is part of the once-secret Santa Susana Field Lab. Founded in 1947 to test experimental nuclear reactors and rocket systems, the research facility was built in the hills above the two valleys. In 1959, Area Four was the site of one of the worst nuclear accidents in U.S. history. But the federal government still hasn't told the public that radiation was released into the atmosphere as a result of the partial nuclear meltdown.

Now, whistleblowers interviewed on camera by NBC4 have recounted how during and after that accident they were ordered to release dangerous radioactive gases into the air above Los Angeles and Ventura counties, often under cover of night, and how their bosses swore them to secrecy.

In addition, the I-Team reviewed over 15,000 pages of studies and government documents, and interviewed other insiders, uncovering that for years starting in 1959, workers at Area Four were routinely instructed to release radioactive materials into the air above neighboring communities, through the exhaust stacks of nuclear reactors, open doors, and by burning radioactive waste.

How It Began

On July 13, 1959, the day of the meltdown, John Pace was working as a reactor operator for Atomics International at Area Four's largest reactor, under the watch of the U.S. government's Atomic Energy Commission.

"Nobody knows the truth of what actually happened," Pace told the I-Team.

In fact, Pace said, the meltdown was verging on a major radioactive explosion.

"The radiation in that building got so high, it went clear off the scale," he said.

To prevent a potentially devastating explosion, one that in hindsight the 76-year-old Pace believes would have been "just like Chernobyl," he and other workers were instructed to open the exhaust stacks and release massive amounts of radiation into the sky.

"This was very dangerous radioactive material," he said. "It went straight out into the atmosphere and went straight to Simi Valley, to Chatsworth, to Canoga Park."

Pace and his co-workers frantically tried to repair the damaged reactor. Instead, he said they realized, their efforts were only generating more radioactive gas. So for weeks, often in the dark of night, Pace and other workers were ordered to open the large door in the reactor building and vent the radiation into the air.

"It was getting out towards the public," he said. "The public would be bombarded by it."

Pace said he and his co-workers knew they were venting dangerous radiation over populated areas, but they were following orders.

"They felt terrible that it had to be done," he said. "They had to let it out over their own families."

Area Four workers "were sworn to secrecy that they would not tell anyone what they had done," Pace explained.

He remembered his boss getting right in his face and saying, "You will not say a word. Not one word."

That was more than five decades ago, but radioactive contamination didn't just vanish. It remains in the soil and water of Area Four and in some areas off-site, according to state and federal records obtained by the I-Team. And, evidence suggests that the fallout could be linked to illnesses, including cancer, among residents living nearby.

Arline Mathews lived with her family in Chatsworth, downwind of Area Four during some of the radiation releases. Her middle son, Bobby, was a champion runner on the Chatsworth High School track team for three years, running to the Santa Susana Field Lab and back to school every day. Bobby died of glioblastoma, a rare brain cancer often linked to radiation exposure. Mathews said there is no known family history of cancer and she blames the radiation from Area Four for her son's illness.

"He was exposed to the chemical hazardous waste and radioactivity up there," Mathews said. "There's no getting over the loss of son."

The Government Cover-up

Six weeks after the meltdown, the Atomic Energy Commission issued a press release saying that there had been a minor "fuel element failure" at Area Four's largest reactor in July. But they said there had been "no release of radioactive materials" to the environment.

"What they had written in that report is not even close to what actually happened," Pace said. "To see our government talk that way and lie about those things that happened, it was very disappointing."

In 1979, NBC4 first broke the story that there was a partial meltdown at Area Four's largest reactor, called the Sodium Reactor Experiment. But at the time, the U.S. government was still saying no radiation was released into the air over LA.

But during its current yearlong investigation, the I-Team found a NASA report that confirmed "the 1959 meltdown... led to a release of radioactive contaminants."

For years, NASA used part of the site for rocket testing and research.

More Radioactive Releases

After filing a Freedom of Information request, the I-Team obtained more than 200 pages of government interviews with former Santa Susana workers. One of those workers, Dan Parks, was a health physicist at Area Four in the 1960s.

In the early 60s, Parks said, he often witnessed workers releasing radiation into the sky through the exhaust stacks of at least three of Area Four's ten nuclear reactors.

"They would vent it to the atmosphere," he said. "The release was done with the flick of a switch."

Radioactive Waste Up in Smoke

Parks said he often witnessed workers releasing radioactive smoke into the air when they disposed of barrels of radioactive waste from Area Four's 10 nuclear reactors.

"We were all workers," he said. "Just taking orders."

Workers would often take those barrels of waste to a pond called "the burn pits" and proceed to shoot the barrels with a high-powered rifle causing an explosion. The radioactive smoke would drift into the air over nearby suburbs and toward a summer camp for children.

"It was a volatile explosion, beyond belief," Parks said.

Whatever direction the wind was blowing, the radioactive smoke would travel that way.

"If the wind was blowing to the Valley, it would blow it in the Valley," he said.

Ralph Powell, who worked as a security officer at Area Four in the mid-60s, recalled being blanketed by that radioactive smoke.

"I saw clouds of smoke that was engulfing my friends, that are dying now," Powell said.

Powell believes it wasn't just his friends who suffered the consequences. He fears he may have exposed his own family to radiation, tracking it home on his clothes and car.

While Powell was working at Area Four, his son Michael was diagnosed with leukemia — a cancer linked to radiation exposure — and died at age 11.

"I suspect it caused the death of my son," he said. "I've never gotten that out of my mind."

Toxic Chemical Contamination

In addition to the radiation, dozens of toxic chemicals, including TCE and Perchlorate, were also released into the air and dumped on the soil and into ground and surface water from thousands of rocket tests conducted at the Santa Susana Field lab from the 1950s to 80s. The tests were conducted by NASA, and by Rocketdyne, a government aerospace contractor.

According to a federally funded study obtained by the I-Team, "emissions associated with rocket engine testing" could have been inhaled by residents of "West Hills, Bell Canyon, Dayton Canyon, Simi Valley, Canoga Park, Chatsworth, Woodland Hills, and Hidden Hills."

Contamination Moves into Neighborhoods

Radiation released at Area Four continues to contaminate the soil and water of the Santa Susana Field Lab.

In 2012, the U.S. Environmental Protection Agency completed a $40 million soil test of the site and found 423 hot spots — places contaminated with high levels of man-made radiation.

Other studies and government documents obtained by the I-Team show that radiation has moved off-site, and has been found in the ground and water in suburbs to the south, northeast and northwest of the Field Lab.

"Radiation doesn't know any boundaries," said Dr. Robert Dodge, a national board member of the Nobel Prize-winning nonprofit Physicians For Social Responsibility, which studies the health effects of radiation.

Dodge, who has reviewed numerous government and academic studies about the contamination at Santa Susana, said he believes the contamination has spread far beyond the facility's borders.

"If the wind is blowing and carrying radiation from Santa Susana, it doesn't stop because there's a fence," he said.

One of the places radiation has been found, in a 1995 study overseen by the U.S. EPA, was the Brandeis-Bardin Institute in Simi Valley. The Institute is a nationally-known center of Jewish learning, and the home to Camp Alonim, a beloved summer sleepaway camp that has hosted some 30,000 children.

In December 1995, The Brandeis-Bardin Institute filed a federal lawsuit against the present and past owners of the Santa Susana Field Lab, alleging that toxic chemicals and radiation from the field lab "have subsequently seeped into and come to be located in the soil and groundwater" of Brandeis "is injurious to the environment" and "will cause great and irreparable injury."

Brandeis settled the lawsuit in a confidential agreement in 1997.

A spokesman for the Brandeis-Bardin Institute, Rabbi Jay Strear, told NBC4 that the groundwater and soil is "tested routinely," and the results have shown the "the site is safe."

The I-Team asked Brandeis-Bardin to provide NBC4 with those test results showing the site is safe and free of hazardous substances. The Institute refused, and in an email said "we are not in a position to devote the required staff time to respond to your more detailed inquiries, nor do we see the necessity for doing so."

A government scientist who has studied the contamination at Santa Susana told the I-Team he thinks there's a continued threat of radiation and toxic chemicals flowing from the field lab to places like Brandeis-Bardin, via groundwater and airborne dust.

Clusters of Cancer

Researchers inside and out of government have contended that the radiation and toxic chemicals from Santa Susana might have caused many cancer cases.

"The radiation that was released in 1959 and thereafter from Santa Susana is still a danger today," Dr.Dodge said. "There is absolutely a link between radiation and cancer."

The I-Team tracked down dozens of people diagnosed with cancer and other illnesses who grew up in the shadow of Santa Susana — in Canoga Park, West Hills, Chatsworth, Thousand Oaks, Simi Valley. Many of them believe their cancers were caused by radiation and chemicals from the field lab.

Kathryn Seltzer Carlson, 56, and her sisters, Judy and Jennifer, all grew up in Canoga Park around the time of the nuclear meltdown and for years after, and all have battled cancer.

"I played in the water, I swam in the water, I drank the water" that ran off the Santa Susana Field Lab, said Carlson, who finished treatment for ovarian cancer earlier this year and is now undergoing chemotherapy for lymphoma. "I've had, I don't know how many cancers."

Bonnie Klea, a former Santa Susana employee who has lived in West Hills since the 60s, also battled bladder cancer, which is frequently linked to radiation exposure.

"Every single house on my street had cancer," Klea said.

A 2007 Centers for Disease Control study found that people living within two miles of the Santa Susana site had a 60 percent higher rate of some cancers.

"There's some provocative evidence," said Dr. Hal Morgenstern, an epidemiologist who oversaw the study. "It's like circumstantial evidence, suggesting there's a link" between the contamination from Santa Susana and the higher cancer rates.

Silence From the Government

For more than two months, the I-Team asked to speak with someone from the U.S. Department of Energy (DOE), the federal agency that's responsible for all nuclear testing, to ask why workers were ordered to release dangerous radiation over Los Angeles, why the DOE has never publicly admitted this happened, and what it plans to do to help get the site cleaned up.

The DOE emailed the I-Team, "We will not have anyone available for this segment."

So the I-Team showed up at a public meeting this month about Santa Susana and asked the DOE's project manager for the site, Jon Jones, to speak with us. He walked away and wouldn't speak.

Will the Contamination Ever Be Cleaned Up?

Community residents, many stricken with cancer and other radiation-related illnesses, have been fighting for years to get the government and the private owners of the Santa Susana Field Lab to clean up the contamination that remains on the site.

But efforts in the state legislature and state agencies that oversee toxic sites have, so far, stalled.

But residents, with the support of some lawmakers, continue to fight for a full cleanup.

"People are continuing to breathe that (radiation) in and to die," Chatsworth resident Arline Mathews said.

"See that this is done immediately, before more lives are lost."