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
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.
"The real challenge is going to be getting in and installing it safely, in a way that you're not exposing people to hazards," Mr. Yarmak said, adding that much of the work will likely have to be done remotely, via automated equipment.
Even at Pennsylvania's Three Mile Island, where the reactor vessel remained intact after a partial meltdown in 1979, removing the fuel by remote-controlled machinery was a tricky engineering feat. Although great strides have been made in robotics since then, damage to the containment vessels at the Japanese site renders the effort much more complex.
Contrary to any speculation the ice wall will cost far more than the estimated $320-million, Mr. Sopko said the price tag actually seems "astronomical" – his Aquarius project cost about $30-million in 1998 – but added that the steep cost might be attributed to dealing with safety concerns.
"Production could be very slow because there'll be limited time that people can be out there – workers will have to come back in and decontaminate," he said. "The biggest challenge will be the protection of the workers putting this thing in."
Confronting naysayers
Beyond workplace safety, critics have raised several concerns about Japan's announcement this week – from the ice wall's lifespan to power issues to the timeline to the reliability of the ice wall to begin with.
For Mr. Yarmak and Mr. Sopko, though, none of those worries seem particularly well-founded.
Typically, ice walls aren't conceived to last more than a few years, and the Fukushima decommissioning process is expected to take about four decades. But Mr. Yarmak said even the Tennessee project – designed to last just six years – could have gone on at least another 20 before needing new machinery. The pipes themselves, he said, could have lasted 50 to 100 years.
Mr. Sopko added that there are a few frozen-earth projects in the U.S. that have been designed to store liquid propane underground "almost permanently."
As for the concern that the project will require such electrical heft that outages will be inevitable, both experts pointed out it takes a long time for an ice wall to thaw. Mr. Yarmak, for example, said he ran a 10-day outage test on the Tennessee site and found he lost only 1 per cent to 2 per cent of the wall in that time.
The project is expected to be completed in less than two years – a time frame both Mr. Yarmak and Mr. Sopko said is realistic, even with safety issues. Mr. Yarmak finished the Tennessee wall in four months, while Mr. Sopko said the Ontario ring took about a year to finish. (It was never activated because a drop in gold prices made it uneconomical, he said.)
Mr. Sopko said he was initially concerned that the groundwater near the Fukushima plant might be travelling too fast, causing technical issues when it meets the ice wall.
"You can really run into problems if the water is moving faster than one metre per day," he said. "My understanding is it's only moving 10 centimetres a day, and that's well within the capacity of this particular type of refrigeration system."
The Chernobyl model
Critics such as Harutoshi Funabashi, a Hosei University sociologist who led an academic review of the recovery efforts post-disaster, said Japan's plan is "just a tactic to avoid taking responsibility" and facing an angry public.
He and others say Japan should consider other options, including the approach taken by the former Soviet Union in the aftermath of the 1986 Chernobyl disaster. Back then, the government essentially capped the battered reactors with concrete and declared the most contaminated towns off-limits for a generation.
"Admitting that no one can live near the plant for a generation would open the way for all sorts of probing questions and doubts," Mr. Funabashi said, explaining his theory for the government's plan.
Mr. Sopko pointed out that the large amounts of groundwater under the plant mean that pouring concrete wouldn't contain the spread of radiation. "It wouldn't solve the sub-surface problem," he said.
Japanese officials said giving up on a large portion of Fukushima is not an option in a densely populated country where land remains a scarce commodity. But they also suggested that the reason for eschewing a Soviet-style option may be the fear that failure could turn a wary public even more decisively against Japan's nuclear industry.
"If we just buried the reactors, no one would want to see the face of another nuclear power plant for years," said Shunsuke Kondo, chairman of the government's Atomic Energy Commission.