Temporary cover in place over breached Hanford radioactive waste tunnel

Heavy plastic was pulled over the top of a Hanford waste storage tunnel on Saturday, helping keep the radioactive contents of the tunnel contained while a more permanent fix is planned.

A 360-foot-long tunnel at the nuclear reservation’s PUREX processing plant was discovered to be partially collapsed on May 9.

“Since this event began, our focus has been on protecting our workers, the public and the environment,” said Doug Shoop, manager of the DOE Richland Operations Office. “Installing this cover will provide additional protection as we evaluate other actions to further ensure the safe storage of the waste.”

The approximately 20-by-20-foot breach in the top of tunnel already had been filled with 53 truckloads of sand and soil to prevent any radioactive contamination exposed in the tunnel from becoming airborne.

Federal and state officials say they have found no evidence of contamination spread into the atmosphere.

Hanford officials had to wait several days for spring winds to calm at Hanford before taking the next step, installing a plastic cover over the tunnel.

The 400-foot-long and 100-foot-wide piece of industrial plastic was rolled out along the length of the tunnel in central Hanford on Friday.

A CH2H Hill Plateau Remediation Co. crew pulled the plastic up and over the soil berm that tops the tunnel on Saturday, using a manlift — a lift holding a person that can be telescoped over the berm — to pull and guide the plastic.

“The crew did a great job,” said Ray Geimer senior recovery manager for CH2M.

The plastic has a high-density polyetheylene woven core and is resistant to puncture, abrasion, chemicals, ultraviolet rays and oxidation, according to DOE.

It is planned to keep rain from soaking into the eight feet of soil above the tunnel, which would add more weight to the roof. It also should help keep radioactive particles out of the atmosphere should more of the tunnel collapse.

It will be held in place by almost 150 concrete ecology blocks, each weighing 3,800 pounds, and cables from the ecology blocks criss-crossing across the berm.

Blocks had been placed along the plastic on the western side of the tunnel as it was rolled out on Friday. By 5 p.m. Saturday, a crane had placed ecology blocks along a third of the eastern side, with sandbags serving as temporary weights.

Work was expected to continue through Saturday night to place the rest of the blocks. The cable lacings are planned to be added on Monday.

Just past noon on Saturday, restrictions on access near PUREX were lifted, and employees in the area may again report to their normal work locations. Tank farm employees who usually work nearby had been assigned to alternate locations last week.

The Department of Energy has posted online data collected by both DOE and the Washington State Department of Health after the breach was discovered. Go to hanford.gov and click on PUREX Tunnel Emergency Response Archive on the rotating slides near the top of the page.

Contamination surveys, radiation surveys and air sampling showed no elevated readings or activity above background, according to DOE. The data was collected, as shown on the online map, both in central Hanford and at locations from Richland to the Hanford Reach National Monument north of the Columbia River by both the state Department of Health and DOE.

The technical information included on the charts DOE has posted shows “readings at very, very low levels,” said Earl Fordham, of the state Department of Health.

Small amounts of radioactive cesium can be detected from previous above-ground nuclear tests around the world, he said. Results may also include cosmic radiation from outer space or radiation from naturally occurring sources, such as granite containing uranium and thorium.

Next week DOE and CH2M will work with the state Department of Ecology, a Hanford regulator, on additional actions to ensure the safe storage of the waste until a decision is made on permanent disposal of the waste.

Department of Ecology officials have said filling the tunnel with grout is being considered.

The tunnel, built of creosoted timbers, was filled with eight flatbed rail cars in the early 1960s. They hold large pieces of equipment contaminated with radioactive waste from work in PUREX. The plant was used to chemically process irradiated uranium fuel to remove plutonium for the nation’s nuclear weapons program during the Cold War.

This story was originally published May 20, 2017 at 5:48 PM with the headline "Temporary cover in place over breached Hanford radioactive waste tunnel."