Sawdust. It’s not the first thing most people would choose to put between themselves and highly contaminated radioactive water. But a mixture of sawdust — ogakuzu in Japanese — with chemicals and shredded newspaper is precisely what nuclear safety authorities and power plant officials turned to in trying to plug a 8-inch crack in a shaft near reactor 2 at the Daiichi nuclear power plant in Fukushima over the weekend.
Unfortunately, like the concrete they tried before it, the sawdust didn’t work, and as of Monday, the flow of irradiated water into the sea from the shaft continued unabated. “We have not succeeded yet,” Ken Morita, director of the international affairs office at Japan’s Nuclear and Industrial Safety Agency (NISA), acknowledged to TIME on Monday morning. “We will try again today.”
What will they try next? For the past three weeks, that has been the question hovering in the irradiated air above Fukushima, where each passing day seems to bring a new and unprecedented challenge for the ebattled Tokyo Electric Power Company (TEPCO) to shut down the reactors at the Fukushima nuclear power plant safely.
Since Saturday, when TEPCO announced that workers had detected radioactive water flowing directly into the ocean, the crisis of the hour has been stopping and mitigating the impact of the newly found leak. On Saturday, NISA said it had found seawater about 25 miles south of Fukushima contained twice the normal limits of radioactive iodine. Officials say dye has now been added into the water to be able to trace the movement of leaked radioactive particles, and that workers will be setting up a physical barrier near the plant to try to stop their flow out of the direct area. “There are many important things to do, but in this current situation, many people are focusing on stopping the outflow,” says Morita. “Many options are now under consideration but we have not decided on anything.”
(See our full coverage of the Japan’s triple disasters.)
That kind of opacity — whether a symptom of sheer improvisation or a more calculated attempt to cloak the severity of an unsolved problem — has not won TEPCO, or the Japanese authorities, any fans in the international nuclear community. Without more information about what is happening at the crippled plant, nuclear experts outside Japan have been left to guess what the extent of the problems are and what, if anything, could be done differently to help solve them. In the case of the found leak, for instance, TEPCO has not released information about where exactly the crack has occurred, and so the question of why the concrete or sawdust mixture isn’t working – or what might be a better material to fix it – is at this point a matter of speculation. “It’s very difficult to say whether they have done the right thing or not,” says Dr. Bing Luk, chairman of the nuclear division of the Hong Kong Institution of Engineers. The argument can be made, he says, that Japan is “fighting a big battle so they don’t have time to release [the information], but everyone will be effected by this. Everyone is keen to know what’s going on.”
Fixing the leak, coming from a shaft containing electric cables near reactor 2 where the level of air contamination was measured at over 1000 millisieverts per hour, is a high priority not only because of its impact on the ocean environment and coastline. It’s also urgent because leaving radioactive water to pool up around the site seriously endangers employees – and seriously hampers getting the plant back under control. “The most important thing is to identify where the sources of the radiation leakage,” says Luk. “They need to try to find a way to repair those leaks as quickly as possible.”
Workers, in spartan and dangerous conditions, have been pulled on and off the job during the past weeks as radiation levels have spiked and receded. Three workers were hospitalized after being exposed to radioactive water last week, and on Wednesday, the bodies of two workers killed during the tsunami were finally recovered in the plant after weeks of not being able to reach them. On Sunday, TEPCO announced they died when they went into the plant to check on it after the 9.0 earthquake hit off Japan’s coast on March 11.
Meanwhile, Tepco must also continue to keep the fuel rods from overheating by pouring water into the affected reactor cores and spent fuel pools until the entire cooling system is back online. Though the external power supply to the plant has been recovered after the quake, and some elements in the reactors like lighting and some monitoring equipment are now hooked up to that electrical supply, Morita says “the connection to the cooling system is not working yet.” The problem is maddeningly circular: workers can’t safely fix the power connection while there is so much irradiated water around, but workers can’t stop dousing the plant with water while the electricity is down. Dealing with the water will require its own processes. “There is of course a large amount of radioactive water that needs to be contained,” writes Dr. Shan Nair, a British nuclear safety expert who was part of a panel that advised the European Commission on its response to the Chernobyl disaster in 1986. “The best course of action would be to store this water in secure containment tanks for a while until the shorter lived radionuclides [radioactive isotopes] decay away.”
That does not, however, appear to be the plan for now. In the shuffle to prioritize, a cabinet minister said on Monday that at least 11,500 tons of low-level radioactive water collected from around the plant will be dumped into the ocean. That water, officials say, has lower levels of radioactivity than the water leaking out of the cracked concrete shaft, and getting it rid of will make room to store the more dangerous water coming out near Unit 2.
At some point in the not too distant future, TEPCO will have to come up with a plan to physically isolate the entire plant from its surroundings, suggests Luk. “Imagine a concrete building around the plant in which you close off the whole area,” he says. He says because of the current radiation levels the structure, which could take months to build, will have to be pre-fabricated off site, shipped in, and built quickly around the plant. Because it’s still unknown how badly the fuel in the reactor cores of Units 1, 2, and 3 are damaged, it’s impossible to know what needs to happen inside that structure once it’s built. If the fuel has not been badly damaged, workers could remove it to storage pools and left to cool in the same way that spent fuel cools. If it has somehow melted together and cannot be safely moved, then engineers may need to leave the area isolated for a much more prolonged period, like Chernobyl.
But without knowing more, it’s hard for anyone — including the IAEA — to say what the best holistic course action might be. “Without knowing what’s happened, we cannot assess the situation accurately,” he says. “I guess there will be plenty of lessons we will learn from this accident. At least one is how [the nuclear industry] should disseminate information. We need to be able to plan what to do.”
—With reporting by Eben Harrell / London