Source: Tri-City Herald | Annette Cary | August 28, 2018

Capture tunnel illustration.JPG

An illustration shows what could happen if corrosion causes one steel beam to fall at a Hanford waste storage tunnel, leading to more beams falling. (Credit: DOE)

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.

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.

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