A small platform crane hoists two men up near the roof gutter of a flat, one-floor building on the Harborview campus on First Hill. Slowly, one of the men moves a thick, round bar roughly six inches along the gutter with his right hand, stops, and then looks at the radiation survey meter in his left. Then he moves the bar another six inches. And another.

If there is any radiation left from the leak of radioactive material that left 13 people exposed during the decommissioning of an irradiator device in the middle of Seattle on May 2nd, these men will find it and wipe it down.

The concrete L-shaped loading dock and parking lot, wedged between the UW Medicine Harborview Medical Center Research and Training Building and a small administrative building near Terry Ave and Terrace, is already polka-dotted with white paint marks, designating areas where potential traces of Cesium-137 were found.

While being checked for radioactive residue, the R&T building is still on lockdown. State Patrol troopers guard the fenced-off entrances to make sure no one can go in and out. From behind the chain-link, there is not much to see — no Chernobyl-like scenes here — except for a sidewalk-wide stripe of white paint near the loading dock doors and a white plastic box covering the ventilation system. The parking lot exudes a ghostly calm.

Here, the night of May 2nd, crews from the Seattle Fire Department rushed to the scene to try to make sense of a rare incident that involved more than 50 people from at least six different agencies, including the department’s HAZMAT team, the Washington State Department of Health, the FBI, University of Washington, and a clean up crew with over 40 officials from the US Department of Energy.

More than six weeks after the leak, little is publicly known about what happened that night — and what went wrong.

Records obtained by CHS, reports by the Nuclear Regulatory Commission, as well as interviews with officials from the University of Washington, Washington State Department of Health and the US Department of Energy’s National Nuclear Security Administration shed more light on the night of the leak, and the aftermath.

The plan for that night, with preparations launched early this year, had been months in the making.

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An irradiator, a medical device containing radioactive material used in research on the connections between bone marrow cells and immune response in a lab at the R&T building, would be decommissioned and moved to a safe disposal site with the help of International Isotopes, a contractor hired by the US Department of Energy. International Isotopes, an Idaho-based public company valued at $20.85 million, routinely performs these kinds of operations where they go into hospitals, blood banks, and research centers to help decommission medical machines with radioactive material.

This irradiator at the R&T building was, like many others, for years filled with research samples to be sterilized with the help of the radioactive isotope cesium-137, which kills HIV, Hepatitis and other viruses, bacteria, and pathogens.

In an irradiator, blood and research samples are exposed to the radiation of cesium-137, a white powder, through a briefly opening radiation-blocking window, like a camera shutter system. This all happens inside the machine. Multiple tubes of metal containers surround the cesium-137, to make sure nothing can escape. That would be incredibly dangerous. Exposure to large amounts of cesium-137 can cause burns, radiation sickness and increase the risk of cancer– and in case of very large quantities, death.

Because cesium-137 is so easily dispersed in air, this also makes it an “ideal” material for a dirty bomb. That’s why an FBI officer and State Patrol Troopers are usually on site during a procedure like this.

And that’s why the State Patrol Troopers are still there weeks later on First Hill, guarding the entrances to the building in unmarked patrol cars. The radioactive source and the irradiator are still inside the building while the investigation runs its course.

“Cesium-137 is one of the isotopes of most concern in what’s called ‘nuclear nonproliferation,'” said Leigh Winfrey, Ph.D., Associate Professor of Nuclear Engineering at Pennsylvania State University. “It could potentially be a target for terrorists to take and put it in regular bombs, because it’s easily dispersed [in the air], it dissolves in water. It would be really, really nasty if it was distributed with a regular bomb.”

After 9/11, concerns about dirty bombs increased, so the Department of Energy’s Off-Site Source Recovery Program (OSRP), which recovers excess and unwanted radioactive sources, expanded its efforts to decommission more types of sources that contained high amounts of radioactive material, particularly so-called “high-risk” sources greater than 130 curies.

Decommissioning the device at Harborview — which contained 4,000 2,800 curies of cesium-137 — was part of a fairly common phasing-out procedure for hospitals and labs across the country. But a leak like this is not. The state Department of Health called it “very rare,” as did Winfrey.

“This kind of material doesn’t just sort of sit around,” Winfrey said. “so we’re usually very, very cautious.”

For the decommissioning process on May 2nd, this meant that seven International Isotopes contractors would be, in keeping with protocol, accompanied by an FBI officer, inspectors from the Department of Health, and two radiation experts from UW.

The procedure wouldn’t take more than one night. They would start after 5 PM and perhaps get the device out by daybreak. By the morning of May 3rd, the irradiator and vial of cesium-137 would be on trucks to be shipped to safe disposal sites, and the roughly 200 researchers and employees of the R&T building would be able to go back to their jobs and into their labs running tests on sexually transmitted diseases, Alzheimer’s, vaccine trials and other research.

But that isn’t what happened.

The first leg of the procedure went fine. The machine had been moved, with a crane, to the loading dock area, basically a garage (a couple of floors above the vivarium that holds live animals, mostly rodents, for research). International Isotopes contractors had set up a secure steel “chamber” wherein they would perform a crucial, most perilous part of the operation: removing the capsule with cesium-137 from the irradiator.

Separating the two before transport is not out of the ordinary. Winfrey said that transporting the capsule within the irradiator would be extremely unsafe and against regulation — there are special transport casks for the radioactive capsule that can withstand accidents and even missile hits.

And so, the crew, wearing steel-toed boots and gloves deployed a “grinding wheel” to remove a tungsten plug that held a protective sleeve around the capsule. Tungsten is both very hard and brittle, difficult to cut and tends to shatter. That might have made the cutting work harder. At some point, the capsule with cesium-137, instead of just the tungsten plug, was cut.

“Generally, once that pin is removed, the source holder is removed from the plug and the source [cesium-137 capsule] can be accessed,” said Leslie Velarde, Public Affairs Specialist for the DOE’s National Nuclear Security Administration. “There was never an intent to cut the source itself.”

Quickly, an unknown amount of cesium-137 spread into the irradiator, the “chamber,” the loading dock and a 100-feet radius around the loading dock, plus the first three floors and one stair of the R&T building, resulting in “widespread contamination.” UPDATE: We have updated the description of the amount of cesium and the amount released to reflect updated information after a miscommunication with an official. The exact amount of the leak is under investigation and will be quantified once the source is taken to a laboratory for analysis. We regret the error and will update once we hear back.

The leak happened at 9.30 PM and was discovered during a regular and procedural wipe-down, meant to see if any material had been released.

A 911 call, from the on-scene Weapons of Mass Destruction (WMD) coordinator, came in about an hour later, at 10:25 PM. The message: there has been a “radiation leak from a blood irradiator,” a draft report from the Seattle Fire Department notes.

Quickly, the Seattle Fire Department Hazardous Materials Response Team (HAZMAT team) speeds to the scene. When they get there, tape has already been hung to cordon off both entrances to the parking area.

The UW Radiation Safety Officer, who was on site for the operation and had most likely been exposed to the radioactive material himself, tells the Fire Department seven contractors are still inside, attempting to “weld the breach shut.”

Apart from them, he says, six others had been in the building: janitors who had “possibly been exposed to the contamination” and had been ushered to the corner of Alder and Terry some 150 feet away, waiting to be screened for contamination.

Meanwhile, the HAZMAT team is not getting many answers from the safety officer: Which material exactly, leaked? Was it granular? A powder? “We attempted to question” the UW Radiation Safety Officer to develop an action plan, but “were not provided pertinent information,” the draft report states.

“We had no official prior knowledge of the decommissioning of the irradiator and therefore were not aware of the site action plan or any pre-planned emergency actions,” it reads.

Only later did the team find out it was cesium-137 “in talcum powder form,” which is highly dispersible in the air. And it was only when they asked whether the HVAC system for the building had been secured that the UW safety officer called someone, the report notes. Within minutes, it is shut down.

With information streaming in slowly, the HAZMAT Team posts up on the north side of the building because of a south wind and come up with their action plan on the fly, calling in help from a decontamination team, battalion chief and three fire engines, plus a medical services officer.

That night, over 30 people from the fire department are called to the scene. They also notify the FBI, the Washington National Guard’s 10th Civil Support Team, Radiological Assistance Program Region 8, the Environmental Protection Agency and Seattle Public Utilities. The Federal Emergency Management Agency and Department of Homeland Security are also notified.

Though the information about what is happening is incomplete and still coming in, the HAZMAT team — decked out in protective suits — takes the situation seriously. They judge the contamination potential “significant” based on the type of radioactive material, radiation counts, and “the lack of PPE [Personal Protective Equipment] worn by everyone exposed.”

Kate Lynch of the Department of Health said it wasn’t unusual that the team in charge of the decommissioning were not wearing higher-level Personal Protective Equipment because usually, “it’s a pretty simple process.”

At least, the Fire Department notes, no one seemed to be in urgent medical need. The patients were wiped with dry and wet hand wipes to get the “contaminant” off, and once they were cleared, “wrapped in temporary clothing” and moved to Harborview in ambulances.

In total, 10 people, the International Isotope contractors, the FBI agent and two UW employees were sent to the hospital and placed in a contained area of the Harborview Medical Center Emergency Room, though in the end, only the seven contractors submitted blood and urine samples, with the highest exposures hovering near 55 millirems of radiation.

Those doses, Winfrey explained, were in the order of about 1 mammogram, around 10 to 12 flights across the country, or about a quarter of a CT scan. “That’s not much at all,” she said.

With the people exposed at the hospital, decontamination could begin. Outdoor louvers and doors to the loading dock were covered with heavy plastic. A team from The Department of Energy surveyed the building floors, while International Isotopes employees inspected the parking lot area, marking spots with radiation levels with white paint.

At 5:51 AM, everything was somewhat under control again. By 10 AM, all of the ”patients’ had been evaluated and released from the emergency department.

Things were far from being back to normal, however. That the HVAC system was shut off to prohibit the cesium from spreading through the building was a good thing. But as it stayed off, in the days after the leak, the building started to heat up. Which meant the freezers in the building, which keep research specimen at -80°C, had to work harder to stay cool. Some were failing. Important research samples were in danger.

“Hundreds of thousands of dollars worth of equipment, labor, and samples are being lost on a daily basis. This could destroy the careers of people who have been working their entire lives on research meant to save lives and improve public health and hospital outcomes,” an anonymous source told KIRO.

UW/Harborview personnel moved the contents of some units to other freezers nearby about a week after the spill, said Susan Gregg of the UW Medicine.

“If they were showing signs of failure, the materials were moved to other freezers,” Gregg said. “We were very diligent that none of those research specimens were damaged.” No specimens were found to have any contamination, she added. The animals, mostly rodents, held in the building’s vivarium, have all been moved to another location as well. It took about two weeks for the HVAC system to be turned back on.

Just this Tuesday, teams went into the building to remove bio-waste, infectious disease materials left over from experiments, and materials from incubators where things were growing since the event.

Most R&T Building employees have resumed work, said UW. Some researchers, wearing booties and gloves and escorted by someone from the clean-up crew, were able to go into the building to retrieve some samples to continue their work in other UW labs across the city.

Ana Mari Cauce, President of the University of Washington, declared the situation an “emergency of an extraordinarily severe and extended nature,” said Gregg, who called such a declaration “pretty unprecedented.” Cauce “authorized University leaders with authority over the impacted worksite to take necessary measures, including release with pay in appropriate situations.”

UW also said it was too early to “speculate to the potential costs incurred.”

Tina Mankowski of UW Medicine said that up to now, no-one had asked for a compensation of any kind and that the UW’s HR department is in touch with the union representative of the seven janitors (also UW employees) working in another part of the building that night.

UW said a notification went out to all employees of the building ahead of the planned decommissioning event on May 2nd, including the supervisors of the janitors. Asked if the janitors were supposed to be in the building that evening, Mankowski said, “I believe so.”

Meanwhile, the decontamination — meaning measuring radiation levels with handheld detectors as well as vacuuming, sweeping and wiping up of the residual materials — continues, while both the irradiator and radioactive material remain in the building in a shielding cask.

Questions remain as well. What precisely went wrong during the cutting process? What happened in the hour between the breach and the call to the fire department? And, as the responding fire department crew notes in the draft report: Why was the fire department not informed of the operation or pre-planned emergency plan? The Seattle Fire Code does not require it for this particular situation, said a Public Information Officer from Seattle Fire. And why did they not put up a barrier on the doors and vents beforehand?

“We don’t know the reason [for] the process that they used,” said Kate Lynch of the DOH. “That’s something that is being investigated. They’re [DOE] going to move it [the irradiator and source] to one of the national labs. They are going to recreate what happened in a controlled environment.”

Only then, the capsule and irradiator will be moved to their original destination by the Department of Energy contractors who are busy cleaning the building as we speak. About four dozen people from the Department of Energy have traveled to Seattle to oversee the investigation and clean-up.

Only when the Department of Health gives the green light, the building will reopen. That will take months, probably until after Labor Day said a UW spokesperson. “And we don’t even know how long after Labor Day.”