Tons of contaminated water posing huge hurdles to cleanup
A lot of ink was consumed by media after the Fukushima Daiichi Nuclear Power Station disaster in March 2011, and then everything got quiet. With most of the media silent about the cleanup, the public may think the worst is over and the operating company TEPCO (Tokyo Electric Power Co.) is cleaning up the site.
Nothing could be further from the truth.
Once the remediation efforts began on the irradiated plant site, it quickly became clear the contaminated water being stored at Fukushima was going to be the largest component to the mediation efforts.
Water from the devastated reactor cooling system was leaking out into the ocean, allowing it to spread into the immediate vicinity and around the world through ocean currents. Added to this, rainwater runoff coming from the surrounding mountains flowed through the devastated site, picking up radioactive material on its way to the ocean.
The influx of contaminated water prompted grave concerns over the impact on sea life in the area and around the world.
Rapid expansion in number of storage tanks
Water, water everywhere
The first response to combat the water contamination problem was to reject remediation proposals given by experts, such as building a concrete wall 60 feet into the ground to stop the estimated 76,000 gallons of groundwater from leaking into the ocean. Instead, TEPCO hurriedly constructed plastic- and clay-lined underground water storage pits that soon developed leaks.
When that plan didn’t work, their next step was to build above-ground storage tanks – a lot of them – to store the cooling water and some of the groundwater runoff. At the time, there was no good, efficient way to clean the water, so TEPCO just kept building more tanks to try to stay ahead of the problem.
As the tank farm grew, it was discovered that more than 300 tons of radioactive water had leaked out of a storage tank onto the site. The 2,400 gallons of water per day leaking into the ocean was heavily contaminated with strontium-90 and cesium-137. With so many tanks on the site, more leaks were anticipated.
To solve the problem, plant and government officials then decided to build an “ice wall” around the reactor site to halt the flow of water. The plan was to construct a $300 million mile-long subterranean ice wall around the complex to collect the runoff, funnel it into trenches, freeze it and then transport it to safe disposal sites elsewhere.
The technology was not new. Ice walls have used in the mining industry for years, but it’s the first time it was constructed and deployed in radioactive conditions by workers in bulky and cumbersome radiation suits. Work commenced on the ice wall in June amid much skepticism in the scientific community.
Part of the work was the effort to create an “ice plug” in a tunnel to stop water from flowing into the Number 2 reactor building and becoming contaminated. Stopping the flow of water would have allowed clean-up personnel to pump the water out of the reactor and treat it.
Engineers from TEPCO have injected more than 400 tons of ice and dry ice (frozen carbon dioxide) into the tunnel in an effort to freeze a section of the passage solid.
Written by STEVE ELWART
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