The 1,700-foot-long tunnel, built in 1964, holds dozens of rail cars loaded with failed or obsolete equipment that is highly contaminated with radioactive waste.

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RICHLAND — The possible collapse of a second Hanford tunnel storing radioactive waste is both more likely than thought a year ago and the effects potentially more severe, according to Hanford officials.

The risk of failure, based on Department of Energy nuclear safety standards, has increased from “unlikely” to “anticipated,” and the potential severity has been increased from “low” to “moderate,” according to the ranking.

The severity of the possible collapse is still not ranked as “high,” but it would be a significant event, with the potential for the airborne release of radioactive particles, said Dan Wood, chief operating officer of the CH2M Hill Plateau Remediation Co., a Hanford contractor.

After the partial collapse in May 2017 of the older of two tunnels storing radioactive waste at Hanford’s PUREX processing plant, an initial structural analysis of the second and longer tunnel was conducted.

The analysis concluded that the second tunnel, built in 1964, needed to be stabilized.

But concerns increased after a video inspection of the interior of the tunnel was done this spring, Wood said.

At a hearing Monday night, he explained the risks posed by the nuclear reservation’s second tunnel.

The meeting focused on whether the Washington state Department of Ecology, a regulator of the nuclear reservation, should allow DOE to fill the tunnel with concrete-like grout.

Public comment was split on the issue, particularly on whether the state should allow grouting to start before the end of a public comment period.

DOE wants work to begin within weeks to stabilize the tunnel before the worst of the winter weather.

The Department of Ecology has said DOE must wait to allow the public to weigh in before it is possibly allowed to take the irreversible action of filling the second Hanford tunnel at the PUREX processing plant with grout.

However, the state continues to receive and consider additional briefings and more in-depth information about the condition of the second tunnel.

Wood said the video inspection showed rusting metal, starting near one end of the 1,700-foot-long tunnel where filtered air was exhausted.

Steel beams were used to reinforce the tunnel after initial construction problems, and corrosion was found both in the bolts used to anchor the beams to concrete arches and in the beams.

Corrosion increases the risk of failure, Wood said. Engineers also are concerned that if one beam fails, there will be a “zipper” effect, with more beams coming down, increasing the potential severity of a failure.

“Structural failure has to be anticipated. It is going to happen,” Wood said. “It’s a 60-year-old facility. It is corroded. Sooner or later it is going to go.”

Airborne radioactive particles could be released into the air, particularly if a beam should puncture a waste package. The tunnel holds 28 rail cars loaded with failed or obsolete equipment that is highly contaminated with radioactive waste.

Mitigating the risk is the eight feet of soil topping the tunnel, which could fall in and help contain the airborne spread of radioactive material.

Fears for safety, and for Hanford’s reputation

Representatives of local government and business interests said at the public hearing that their top priority is that another waste-storage collapse at the nuclear reservation not harm Hanford workers, the public or the environment.

But they also are concerned about what another collapse would do to the region’s and the world’s perception of the Tri-Cities, they said at Monday’s hearing.

As news spread of the May 9, 2017, partial collapse of the first tunnel built at the PUREX plant, the collapse became the No. 1 trending topic on Twitter.

It was bumped down the list only when President Donald Trump fired FBI Director James Comey.

Within 10 minutes of news of the collapse breaking, 10 national news media organizations had called Hanford’s emergency communications center. Within 20 minutes, the story went international, according to DOE.

That was despite the fact that the portion of the roof that collapsed measured just 20 feet by 20 feet and no release of airborne radiation was detected.

“Imagine if a catastrophic collapse happens,” said Pam Larsen, executive director of Hanford Communities, a coalition of local governments.

Eastern Washington is an agricultural region, with wheat and fruit among the crops exported.

“The health and safety of this region is of concern to people who are buying our products around the world,” she said.

The Tri-City Development Council also is calling for the second tunnel to be grouted as soon as possible.

As news of the partial breach of the first tunnel spread, major U.S. and international news organizations posted “inaccurate stories leading to rampant speculation and misinformation being distributed, which was detrimental to the community,” said David Reeploeg, TRIDEC vice president of federal programs, reading from a TRIDEC letter sent earlier this month to state officials.

Regional agricultural producers were getting questions about the safety of their products, and sports organizations were reconsidering whether or not to hold tournaments in the Tri-Cities, the letter said.

“Another collapse cannot happen without it having devastating effects on business and agriculture in this area,” said Steve Anderson, president of the Tri-Cities Local Business Association. “Concerns would be exploded in the public space beyond any real, relative reality.”

Grout now, or wait for public process?

But others at the meeting agreed that the state should complete a public comment process that extends through Sept. 27 before it makes a decision on whether grouting is the best option.

“I am among those concerned about the permanence of grout,” said Susan Leckband. “This is not a sprint. This is a marathon.”

Leckband, the chairwoman of the Hanford Advisory Board, spoke not on behalf of the board but as an area resident and former Hanford worker.

Grouting waste would only stabilize the tunnel, and DOE and its regulators would later need to develop a long-term cleanup plan for the tunnel.

DOE has said it is possible to saw up the grout in large pieces based on the location of railcars and then lift the block of grout out for disposal.

However, another option would be to leave the waste grouted in place permanently in the tunnel, with a cap placed over it to prevent precipitation from infiltrating and possibly spreading any uncontained waste.

Laura Hanses, a Hanford worker, urged the state to consider long-term consequences and costs.

Conn Clark said he opposed grouting. DOE may be racing to make the tunnel a permanent repository, he said.

The first tunnel, which is 360 feet long and stores eight railcars loaded with contaminated equipment, was filled with grout by November 2017. Ecology allowed the grouting under emergency conditions without a public hearing.

A second public hearing is planned at 6:30 p.m. Sept. 5 at the University of Washington Center for Urban Horticulture, 3501 N.E. 41st St., Seattle.