The partial collapse of a radioactive waste storage tunnel at Hanford a year ago was not unexpected.
It was a matter of "when", not "if", some Hanford nuclear reservation observers had speculated as other projects took higher priority.
Hanford watchers said at the time it was a wake-up call. But whether the call has made a difference is up for debate.
Hanford Challenge, a Seattle-based watchdog group, says no.
In the year that followed the tunnel collapse on May 9, 42 workers inhaled or ingested airborne plutonium or other particles of radioactive material.
Those exposures, which occurred during demolition of the highly contaminated Plutonium Finishing Plant, and the collapse of the tunnel were the result of DOE not taking risk seriously enough, said Tom Carpenter, executive director of Hanford Challenge.
Other Hanford watchers say the collapse was the result of limited money to address the most serious risks at the site, as aging facilities — some of them built during World War II — deteriorate.
A fortunate turn
In some ways, the Department of Energy got lucky.
When a gaping hole in the top of the older of the two PUREX plant tunnels was discovered, thousands of workers were ordered to take cover indoors.
They remained inside office trailers and other structures with ventilation systems shut down and windows closed, told not to eat or drink, and waited to learn how bad the emergency was.
Franklin and Benton counties activated their emergency operations centers, and many in the Tri-Cities anxiously waited to hear if loved ones at Hanford were OK and whether the local communities were at risk.
Fortunately, the eight feet of soil that topped the wooden roof of the tunnel fell in, covering the highly radioactive equipment stored beneath the hole.
No airborne radioactive waste particles were detected, and no worker was injured.
The bigger risks
The Hanford Site, employing more than 9,000 permanent workers and additional subcontract workers, remained essentially shut down for three or four days after the partial tunnel collapse, said David Reeploeg, vice president for federal programs for the Tri-City Development Council.
That was despite no spread of contamination. But a worse incident could leave the site shut down not for a few days, but for a few months or a few years, he said.
"I worry that Hanford management tends to be dismissive of these types of risk," Carpenter said. "A large contamination event could be game over for Hanford."
For example, a spread of contamination across the tank farms would make it difficult for workers to get into the area to do the constant monitoring needed to keep waste in the tanks stable.
He questions whether DOE is ready for an event like the collapse of the top of an underground tank, since it was unaware of the imminent collapse of the waste storage tunnel and did not manage demolition of the Plutonium Finishing Plant to prevent the airborne spread of radioactive particles.
An analysis of the airborne spread of contamination during demolition in December showed that there were warning signs that workers could be at risk, but they were overlooked.
There are limits
As much as $2.5 billion a year is spent on environmental cleanup of Hanford, which was used from World War II through the Cold War to produce plutonium for the nation's nuclear weapons project.
Decades of work remain, as a new DOE estimate puts the cost of cleanup yet to be done at $150 billion.
If there was a positive to the partial collapse of the tunnel, it is the realization that nature has its own time limit for the cleanup, said Ron Skinnarland, the waste management section manager for the Washington state Department of Ecology. And unlike DOE, it doesn't grant extensions.
Old structures will continue to deteriorate, and the containers of radioactive waste — buried temporarily until permanent disposal could be arranged — will disintegrate and fall apart.
"There is a new sense of awareness that there is a cost and risk that increases if you delay the work," Skinnarland said.
Since the collapse, DOE's Office of Environmental Management assembled a team to assess similar risk at all of the nation's nuclear cleanup sites' high-hazard excess facilities.
It determined that overall, the sites are appropriately managing risks, according to DOE.
In addition, the two Hanford DOE offices — one responsible for the 56 million gallons of radioactive waste held in underground tanks, the other for all other cleanup — have been working with site regulators to come up with a list of priorities that cross both offices.
It's a joint look that would not have been likely two years ago, said Alex Smith, nuclear waste program manager for the Washington state Department of Ecology.
"To have a sitewide list of all projects and evaluate them comprehensively makes a lot of sense," Reeploeg said.
The result could be changes in legal deadlines to move some projects forward in the schedule and delay others.
"It's a continual job for us to evaluate risk and work on those things that we feel are the more imminent risks," said Doug Shoop, manager of the DOE Hanford Richland Operations Office.
That's where it gets tricky.
Weighing the risks
"At Hanford, there are 50 things you could do, and they are doing one or two at a time," Skinnarland said.
Other projects took priority over cleanup of the PUREX tunnels.
The Hanford Advisory Board had told DOE and its regulators in early 2016 that they needed to hurry up and investigate whether the PUREX tunnels pose a high risk.
The 62-year-old tunnel that partially collapsed was built of timbers, which officials knew were deteriorating from the radiation from eight rail cars loaded with highly contaminated, failed equipment from the PUREX processing plant. The plant was used to chemically separate plutonium from uranium fuel irradiated in Hanford's reactors.
A second tunnel, holding 28 rail cars of highly radioactive contamination, was built in 1964 of concrete and steel. But it also is at risk of collapse, according to a structural analysis done since the problem with the first tunnel.
DOE and its regulators, the Department of Ecology and the Environmental Protection Agency, said in the report they were planning to assess both tunnels, with the first step in the process to be completed by September 2017. That turned out to be four months after the first tunnel partially collapsed.
The Consortium for Risk Evaluation with Stakeholder Participation, a multi-university group, also had raised the issue of the tunnels in an update in September 2015 on a risk review project commissioned by DOE.
A collapse of the storage tunnels, perhaps as the result of an earthquake, could expose people within 100 yards to radiation, it said.
But the tunnels "weren't really considered to be the big risk. There are a lot of them out there," Reeploeg said.
Higher priorities for the DOE Hanford Richland Operations Office, which is in charge of evaluating the tunnels, included ongoing work to get radioactive sludge out of underwater storage near the Columbia River.
Transferring the sludge to central Hanford is close to starting and "will be tremendously important for risk reduction," Shoop said.
The public has demanded cleanup of contaminated groundwater flowing underground toward the Columbia River. DOE has responded by pumping up 18 billion gallons of water and stripping away radioactive and hazardous chemical pollution.
Other high priority projects over the last year have included:
▪ Tearing down the Plutonium Finishing Plant, considered one of the most hazardous demolition projects across the DOE complex.
▪ Preparing to remove stored capsules of radioactive material from an aging concrete pool in central Hanford.
▪ Preparing to dig up a spill of radioactive waste beneath the 324 Building near the Columbia River. The spilled material is so radioactive it would be lethal on contact within two minutes.
The challenge in evaluating risks is that some high risk incidents are not very likely to happen, but others that are lower risk are more certain to happen, Reeploeg said.
"So where do you spend your resources?" he said.
Dramatically increased budgets for Hanford do not appear likely.
In that way, the tunnel collapse was not a wake up call.
Finding the money
The Trump administration proposed cutting budgets for the Richland Operations Office in two budget requests to Congress after the tunnel incident.
Even if budgets remain flat, eventually just the basic work of operating the nuclear reservation and maintaining safety and security will eclipse the budget, Smith said.
About $1 billion is needed annually for basic activities, ranging from operating utilities to maintenance, before any cleanup work is done, Reeploeg said.
In Congress, a strong Washington state delegation has convinced its colleagues to come through with more money for Hanford than proposed by both the Obama and Trump administrations in recent years.
But as other sites are cleaned up across the nation, obtaining strong budgets will only become more difficult. Washington state will have fewer allies in Congress focused on nuclear weapons site cleanup.
In Washington, D.C., much of the attention on Hanford goes to the work of the DOE Hanford Office of River Protection, with 56 million gallons of radioactive waste stored in underground tanks and the $17 billion vitrification plant being built to treat the waste.
"The tanks are a huge risk," Smith said.
Some 67 of 149 single shell tanks have leaked or spilled waste. And the newer, double-shell tanks are outliving their planned design life, with one of 28 already taken out of service after it sprang a leak between its shells.
"It's like the PUREX tunnels. You are just kind of counting on nothing bad happening," Skinnarland said.
Some radioactive elements are long-lived and move through the ground readily with moisture to threaten the groundwater and then the Columbia River.
Carpenter, of Hanford Challenge, is most worried about Hanford waste in underground tanks, and capsules of radioactive cesium and strontium stored in a concrete pool at the Waste Encapsulation and Storage Facility.
Although the capsules are being moved to dry storage, the project is expected to take a few years.
In the meantime, the capsules are at risk of overheating and rupturing if a severe earthquake causes the pool to lose cooling water, Carpenter said.
That or a collapse of a waste storage tank could spread contamination, he said. The events have a low-risk of happening, but a high impact.
"All the work we do at Hanford is risky," Shoop said. "Fundamentally, we're cleaning up the Hanford Site because there is risk to the public and the environment."
As for the tunnels, the older tunnel has been filled with concrete-like grout to prevent a further collapse, and DOE is making plans to do the same with the second tunnel, if regulators agree.