Cover installed over collapsed Hanford tunnel

A protective plastic cover has been installed at the US Department of Energy's Hanford site over the roof of a tunnel that partially collapsed earlier this month. The cover will provide additional protection while longer-term risk mitigation measures are developed and implemented at the site in Washington State.

A protective plastic cover has been installed at the US Department of Energy's (DOE) Hanford site over the roof of a tunnel that partially collapsed earlier this month. The cover will provide additional protection while longer-term risk mitigation measures are developed and implemented at the site in Washington State.

The newly installed cover over the Hanford tunnel (Image: DOE Hanford)

The 40,000 square foot (3700 square metre) heavy plastic cover has a high density polyethylene woven core and is resistant to puncture, abrasion, chemicals, ultraviolet rays and oxidation. It will also limit the intrusion of water into the 8 foot (2.4 metre) layer of soil which covers the tunnel.

Contractor CH2M Hill Plateau Remediation Company placed the cover over the tunnel, securing the sides with heavy concrete blocks. Cables will now be strung across the cover to secure it further.

A site emergency was declared at Hanford on 9 May after the partial collapse of the tunnel, one of two built in the 1950s and 1960s to hold contaminated equipment from plutonium production activities. The emergency was lifted the next day after the hole in the tunnel's roof was backfilled with about 420 cubic metres of soil.

There was no spread of contamination after the partial tunnel collapse or during the emergency response work to fill the hole in the tunnel, and no workers were injured in the incident or the response.

The DOE and CH2M will this week begin working with the Washington Department of Ecology on additional interim actions to ensure the safe storage of the waste until a permanent disposition decision is made.

Hanford was the site of US military plutonium production activities from 1943 until 1987, with nine nuclear reactors and associated processing facilities. The DOE's Richland Operations Office now manages the site, and is responsible for the clean-up of all its remaining waste streams.

Researched and written
by World Nuclear News