NPR – by CAMILA DOMONOSKEEarlier this week, workers in Japan began constructing an underground “ice wall” around the melted-down nuclear reactors at the Fukushima Dai-ichi nuclear power plant. The wall is designed to stop hundreds of tons of radioactive groundwater from leaking into the nearby Pacific Ocean.
Building a subterranean wall of ice sounds a little crazy. NPR’s Geoff Brumfiel, who’s been covering the story, says it is a little crazy — but not as far-fetched as it sounds.
He answered some of our biggest questions about a construction project that sounds like it’s straight out of Frozen.
So … what’s an ice wall?
When you have enough moisture in the soil, it’s possible to actually freeze it. You dig holes every 3 feet for a mile around the plant and put in pipes. Then you run chilled saltwater through the pipes — which freezes at a lower temperature than freshwater — and that causes the soil to freeze. Slowly you can build up an impermeable wall, several feet thick.
When water comes to the wall, it freezes. So you have this self-building wall.
Why ice? Why not build a wall out of, say, steel?
You need something very big, very thick, that can run for miles around the reactors. It’s just not realistic to put in a metal wall, which could degrade over time. The best thing is to try to use something from the environment itself.
This is a technique, incidentally, that’s used in construction for tunnels, for trying to dig foundations in very moist areas like ports. It does work.
Why is it still necessary? The accident happened in 2011.
The problem with the reactors is that they still have hot nuclear fuel inside, and workers have to put water into them to keep them cool. But as you may remember, the reactors were heavily damaged in an earthquake and tsunami — so they leak.
It’s been hard to figure out why, because the inside of the reactors are very radioactive — they can only be accessed by robots.
The site is also between the mountains and the ocean, so there’s a lot of groundwater flowing through it, which mixes with the contaminated water. At the moment most of it is pumped into holding tanks that are popping up around the site, but they’re filling up fast. And some of it is making its way to the ocean as well.
What ideas do they have besides building an ice wall?
They’re trying a kind of crazy system to bypass the groundwater. You dig wells, pump out the groundwater, pipe it around the plant and release it.
But that only takes care of a quarter of the 400 tons a day going through the site.
How much does an ice wall cost?
You can do it for under half a billion dollars.
But remember, that’s just to try to keep things stable. The actual cleanup of the reactors will be billions more.
“The wall is designed to stop hundreds of tons of radioactive groundwater from leaking into the nearby Pacific Ocean”
Leaking? last week they were dumping hundreds of tons of radioactive water into the Pacific ocean.
And all of this madness cold have been dealt with safely if they weren’t more concerned with hiding it from the public, and protecting their profits.
Making a rough calculation of the radioactive water containment required for 1-year:
> 1-gallon of water approximately = 8 pounds
> 300 tons of water per day = 600,000 pounds per day
> 600,000 pounds / 8 pounds = 75,000 gallons per day
> 75,000 gallons x 365 days = 27,375,000 gallons per year
> 1 cubic foot of water = 7.5 gallons
> 27,375,000 gallons / 7.5 = 3,650,000 cubic feet of water per year
This means that in 3-years, Fukushima has lost containment of 82,125,000 gallons or, 10,950,000 cubic feet of radioactive water (into the ground and/or the Pacific Ocean).
A square containment dike perimeter for 10,950,000 cubic feet would measure 3309 feet x 3309 feet x 1 foot deep, every 3-years.
> An Olympic-sized swimming pool contains 88,000 cubic feet of water.
> 10,950,000 cu ft / 88,000 cu ft = approx 124 Olympic swimming pools
I haven’t calculated the energy/refrigeration equipment required to maintain a frozen containment dike of this magnitude — but I doubt it will work. It will be like placing a band aide on a gushing wound.
BTW: I didn’t have time to check my math, but feel this is accurate enough to make my point: that this proposal by Japan is at best, a fruitless endeavor.