Next step on partially collapsed Hanford tunnel — fill it up via Tri-City Herald

On May 9, Hanford workers discovered a section of the tunnel roof about 20 feet long had collapsed, potentially exposing equipment with highly radioactive contamination stored in the tunnel. 

An emergency was declared and initial steps taken to stabilize the 360-foot-long tunnel, which holds eight flatbed rail cars loaded with contaminated equipment from the nearby PUREX processing plant.


The tunnel cannot be filled completely to the top with grout, but having it mostly full means that if another portion of the tunnel roof collapses, there would be far less risk, Smith said. 

There was a concern after the partial tunnel collapse in May that some airborne radioactive contamination might be released, but none was detected by federal and state air monitoring.

Filling the tunnel with grout could be done reasonably quickly without hindering the eventual permanent cleanup of the tunnel and its contents, Shoop said.

“All options are still in play by using this methodology,” he said.


Hanford officials continue to investigate the cause of the tunnel collapse, but have said that the exact reason may never be known.

The wooden tunnel has held waste for more than 50 years. Past reports have speculated about how quickly gamma radiation from the waste might weaken the wood.

The unusually cold and wet winter just past may have contributed to the tunnel collapse. The plastic placed over the tunnel is intended, in part, to keep precipitation from soaking into the eight feet of soil topping the tunnel and making it heavier.

Hanford officials continue to evaluate a second tunnel running parallel to the one that partially collapsed.

“There is nothing to indicate an immediate risk,” Blackford said.

The second tunnel was built in 1964 with more robust materials. It has internal steel I-beams attached to reinforced concrete arches and a steel liner.

It is much longer, at 1,700 feet, and has room for 40 rail cars, but was never filled to capacity. It was sealed up in the mid-1990s with 28 rail cars of contaminated equipment inside.

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