The second of two storage tunnels for radioactive waste from the PUREX Plant at the Hanford Site in Washington state has been stabilized.
Contractor CH2M Hill Plateau Remediation Co. completed work on Friday. “The tunnel has been filled with grout, and we’ve significantly reduced the risk of contaminating Hanford workers, the public, or the environment,” Brian Vance, Department of Energy manager for the Hanford Site, said in a press release.
Grouting began in October 2018, with the project 90 percent complete in early April. The concrete-like material was topped off in recent weeks, filling any remaining voids in the tunnel. In total, roughly 4,000 truckloads, or 40,000 cubic yards of grout, were placed in the tunnel, which is about 1,700 feet long and stores 28 railcars loaded with failed and obsolete equipment contaminated with highly radioactive waste.
Concerns were raised about the second PUREX Plant tunnel, constructed in 1964, after the plant’s first tunnel, built in 1956, partially collapsed in May 2017. Hanford workers were ordered to take cover for hours until officials determined that no radioactive material had been released. The collapse of a section of the tunnel shut down work at Hanford for two days.
A June 2017 structural assessment determined the second tunnel was also at risk of collapse. But concerns increased in spring 2018 when a video inspection of the interior of the tunnel showed corrosion of bolts and weld plates.
The first tunnel was filled with grout under emergency conditions by November 2017.
Grouting was recommended in late 2017 for the second tunnel as an interim step after an independent panel of experts considered options. The panel concluded that grouting would prevent a collapse, while not precluding future remediation of the waste in the tunnel.
Discussions have not begun on final cleanup of either tunnel, but grouting “means the risk to people and the environment is significantly reduced while those decisions are made,” Joe Franco, Energy Department deputy manager for the Richland Operations Office, said in the release.
