At Fukushima, Fear of a Losing Battle; Tepco Builds Sunken Barrier to Ring-Fence Site, but Water May Have Already Overtopped Wall

Updated August 6, 2013, 12:37 p.m. ET

At Fukushima, Fear of a Losing Battle

Tepco Builds Sunken Barrier to Ring-Fence Site, but Water May Have Already Overtopped Wall

MARI IWATA and PHRED DVORAK

To stem the advance of radioactive water to the sea, the operator of the stricken Fukushima Daiichi nuclear power plant has tried plugs, walls, pumps and chemicals that harden the ground into a solid barrier. But as Tokyo Electric Power Co.9501.TO +3.16% prepares this week to start work on a new set of measures that would ring off and cap the area where the most highly contaminated water has been found, some experts and regulators are saying that the battle to completely contain radioactivity to the site of one of the world’s worst nuclear accidents may be a losing one.In the most recent example of Tepco’s Sisyphean struggle, the company said late last week that rising levels of contaminated groundwater may have already overtopped a sunken barrier that the utility started only a month ago, and wasn’t even expecting to complete until late this week.

Fukushima Daiichi: The Battle for Containment

More than two years after suffering one of the world’s worst nuclear accidents, the compound remains a challenge for the operator and regulators.

Tepco’s water-control measures, such as pumping out contaminated water and putting it in storage, are “merely a temporary solution,” said Shunichi Tanaka, chairman of Japan’s Nuclear Regulation Authority, at a news conference last week. Eventually, “it will be necessary to discharge water” that’s still contaminated into the sea, he said.

“We’re taking a number of measures” to counter the recent worries of contaminated-water overflow, Tepco said in an emailed statement Monday. “We’ll continue to strengthen our monitoring of the impact on sea and marine life in the waters near the plant, and work on estimating the outflow of [contaminated water] following our measures.”

Controlling contaminated water has been a struggle at Fukushima Daiichi ever since the March 2011 earthquake and tsunami knocked out the power at the plant and sent its three active reactors spiraling out of control. Some 400 metric tons of water a day is still being used to cool the melted fuel cores—though much of that water is now recycled. More troubling is another 400 tons a day of groundwater that flows down from hills and mountains into the compound, and toward the sea.

For the past two years, Tepco has been trying to keep the contamination contained by pumping accumulated water out of the highly radioactive reactor buildings, and storing it in tanks on the plant grounds. But the company’s efforts went into overdrive a few months ago, when it found that groundwater sampled near the crippled reactors was showing spiking levels of radioactive elements. It was unclear why. What’s more, Tepco said that the water was likely leaking into the sea.

The continuing problems at the reactor site, including the company’s lack of transparency over the radioactive leaks, have drawn criticism from Japanese regulators. On Friday, a newly created task force at Japan’s nuclear regulator held its first meeting aimed at increasing the government’s role in the flawed cleanup process. The panel is also pushing Tepco to improve its communication and credibility at a time of strong public opposition to nuclear power.

As an emergency measure, Tepco last month started to inject the ground near the coast with chemicals that hardened it into an underground barrier. But since then, groundwater levels in the area have risen faster, as they hit the barrier. Recently, Tepco has found that the groundwater has risen to around a meter below the surface—already above the level of the underground barrier, which starts 1.8 meters down.

Now, Tepco is planning to pump out some of the water that’s built up behind the barrier, and store it as well. It’s preparing to extend the underground hardened-earth barrier in a ring around the most heavily contaminated section of coastline, in hopes of heading groundwater off before it can flood in. Tepco is also proposing to cap that ringed section with gravel and asphalt, so nothing gets out. The operator is hoping to get an initial ring of hardened ground done by October.

The company has some other more experimental ideas on the table as well. One involves surrounding the contaminated reactor buildings with a shield of frozen soil.

But there’s a risk to changing the flow of groundwater in the ways that Tepco is considering, said Tatsuya Shinkawa, nuclear accident response director of the Ministry of Economy, Trade and Industry, at a news conference last month. The water could pool dangerously underground, softening the earth and potentially toppling the reactor buildings, he said. Tepco should also try things like using robots to fix cracks in the reactor buildings where the water is likely seeping through.

Freezing soil has its own problems, said Kunio Watanabe, a geology professor at Saitama University. The technology, which is used in civil engineering to dig tunnels, may be able to cut down the amount of groundwater entering the contaminated site, but it is expensive. “You’ll need hundreds of millions of yen to build a system,” Mr. Watanabe said. “You’ll also need a large amount of electricity to maintain the ice walls.”

Mr. Tanaka, the nuclear regulatory chairman, has said that Tepco should admit it’ll never be able to handle all the inflow of water, and start arranging for the release of contaminated water into the ocean, as long as it’s under allowable limits for radioactivity. But local fishery cooperatives, which since June of last year have been catching octopus and other sea life that consistently test low for radiation, are still holding on to the hope that they can eventually get back to business as usual.

“We are in trouble,” said Kazunori Endo, an official of the Soma Futaba Fishery Cooperative, about the latest leaks of contaminated water into the bay. “What if consumers start rejecting our fish?”