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An aerial view shows the Tokyo Electric Power Co.'s (TEPCO) tsunami-crippled Fukushima Daiichi nuclear power plant and its contaminated water storage tanks (top) in Fukushima, in this photo taken by Kyodo August 31, 2013. (KYODO/REUTERS)
An aerial view shows the Tokyo Electric Power Co.'s (TEPCO) tsunami-crippled Fukushima Daiichi nuclear power plant and its contaminated water storage tanks (top) in Fukushima, in this photo taken by Kyodo August 31, 2013. (KYODO/REUTERS)

Energy

How Japan plans to contain Fukushima’s nuclear contamination by building a 1.4-kilometre ‘ice wall’ Add to ...

The Tokyo Electric Power Co. had its chance, and now the Japanese government is stepping in: The government announced it will spend a half-billion dollars trying to stabilize the Fukushima nuclear plant after the 2011 triple meltdown. The timing of that announcement raised eyebrows, coming just days before the International Olympic Committee decides whether Tokyo will host the 2020 Games.

The $470-million (U.S.) vision is ambitious, in part, for its inclusion of a 1.4-kilometre “ice wall” to stave off groundwater contamination – an engineering feat that’s tried and tested, but unprecedented on this scale, under these circumstances. The thought of building a subterranean frozen ring might conjure images from a sci-fi movie, but experts say the plan is feasible, even with its considerable hurdles.

The impetus

Radiation readings taken near a set of tanks holding contaminated water spiked to their highest levels, the country’s Nuclear Regulation Authority said this week. The tests showed radiation levels as high as 2,200 millisieverts – a full fifth higher than that recorded just last weekend.

The radiation, thanks to water that’s been flushed over melted uranium fuel rods to keep them cool, is high enough to kill an unprotected person within hours.

Hundreds of thousands of tonnes of contaminated water – enough to fill more than 130 Olympic-sized swimming pools – is currently being stored in about 1,000 tanks, some of which have sprung leaks and are spilling untreated water onto the ground.

Beyond that, several hundred tonnes of contaminated runoff and coolant is flowing daily from the beleaguered nuclear facility into the ocean via groundwater, the environment ministry says.

Since the March, 2011, meltdown, the NRA raised the severity of the initial leak from a Level 1 “anomaly” to a Level 3 “serious incident” on the international scale of 1 to 7 for radiation releases.

The fix

The plan is to spend $320-million building a 1.4-kilometre ice wall around four reactor buildings and their related facilities, inserting a subterranean system of pipes carrying coolant as cold as –40 C.

The soil around one pipe will freeze and meet the frozen soil around its neighbours, forming a contiguous “wall” of earth that will block a flood of contaminated water from escaping the facility and keep groundwater from entering it.

Japanese construction giant Kajima Corp. is conducting feasibility tests for the ice fence, a concept first proposed by the government and the Tokyo Electric Power Co. (Tepco) in May, and which is slated for completion by March, 2015.

The second and less expensive part of the plan – budgeted at $150-million – is to upgrade the facility’s water-treatment unit, which removes radioactive elements from the water that’s been flushed over the rods.

The NRA chairman has repeatedly said the water eventually has to be released into the sea after it’s processed and diluted, but only with local consent.

Separate from the government’s twin projects, Tepco is also constructing an offshore steel wall along the coast to keep contaminants from spreading further into the sea. The company says radioactive elements have mostly remained near the embankment inside the bay, but experts have reported offshore hot spots contaminated with cesium.

The feat

The notion of building a 1.4-kilometre ice wall 30 metres below the earth’s surface may sound far-fetched, but experts say the project is within the bounds of reality, even though there will be obstacles.

“I don’t think the plan is crazy at all – actually, I think it’s pretty smart,” said Ed Yarmak, the head of Alaska’s Arctic Foundations, which built an ice wall around Tennessee’s Oak Ridge National Laboratory, a producer of plutonium.

Sure, the Fukushima wall will be 150 times longer and three times deeper than the one Mr. Yarmak built in the late 1990s around the Tennessee lab, but it’s only about half as long and a quarter as deep as the one Joseph Sopko built around Ontario’s Aquarius gold mine 15 years ago.

“To me, it seems very reasonable,” said Mr. Sopko, the executive vice-president of Moretrench, a New Jersey-based company specializing in frozen-earth projects.

Both Mr. Yarmak and Mr. Sopko, who is in the midst of working on three ice-wall projects – a proposed eight-kilometre wall in the Alberta oil sands, a sewer project in Toronto and a tunnel in Miami – were unfazed by the Fukushima plan, but cited a key challenge that could drive up the project’s cost, timeline and complexity: the very contamination it’s supposed to thwart.

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