Confidence Slips Away as Japan Battles Nuclear Peril

Ken Belson and Hiroko Tabuchi – New York Times March 30, 2011

After workers switched on the first set of control room lights at Japan’s crippled power plant in Fukushima last week, the Japanese government offered its strongest assurances yet that its nuclear crisis was close to being under control.

Heroic workers and firefighters continued to cool the volatile reactors by pumping in hundreds of tons of water a day. Much-awaited electricity had reached the plant after a rush to extend new power lines, ready to hook up to vital cooling systems and guide the plant to a long-term “cold shutdown.”

But less than a week later, a deluge of contaminated water, plutonium traces in the soil and an increasingly hazardous environment for workers at the plant have forced government officials to confront the reality that the emergency measures they have taken to keep nuclear fuel cool are producing increasingly dangerous side effects. And the prospect of restoring automatic cooling systems anytime soon is fading.

The recent flow of bad news from the Fukushima Daiichi Nuclear Power Station has undermined the drumbeat of optimistic statements by government and company officials who have at times tried to reassure a nervous public that significant progress is at hand — only to come up short.

“The earthquake, tsunami and the ensuing nuclear accident may be Japan’s largest-ever crisis,” the Japanese prime minister, Naoto Kan, told Parliament on Tuesday, in his most sober message to date on the nuclear crisis. “We find ourselves in a situation where we can’t let down our guard. We will continue to handle it in a state of maximum alert.”

The setbacks have raised questions about how long, and at what cost, Japan can keep up what experts call its “feed and bleed” strategy of cooling the reactor’ fuel rods with emergency infusions of water from the ocean and now from freshwater sources.

That cooling strategy, while essential to prevent full meltdowns, has released harmful amounts of radioactive steam into the atmosphere and set off leaks of highly contaminated water, making it perilous for some of the hundreds of workers at the plant to further critical repair work.

Moreover, the discovery of radioactive elements that experts say could come only from the core of a reactor suggest that the government’s strategy may not be working and that partial fuel melting has not been completely halted.

The continuing crisis also underscores the unprecedented scale and complexity of the problems facing Fukushima: a plant ravaged by a magnitude-9.0 earthquake and 45-foot tsunami, and three reactors and four spent fuel pools with no proper cooling system yet and containing more long-lived radioactivity than the Chernobyl reactor, according to the Institute for Energy and Environmental Research, based in Takoma Park, Md.

This is why, despite the damage caused by the efforts so far, Japanese officials have little choice but to continue down the feed-and-bleed path. “The worst-case scenario is that a meltdown makes the plant’s site a permanent grave,” said Tetsuo Iguchi, a professor in the department of quantum engineering at Nagoya University. “In a small island nation like Japan, that’s just not an option. That is why the government is trying to prevent a meltdown at any cost.”

The events have been a quick turn for the worse for the Japanese government. Just last week, officials at Tokyo Electric Power Company, the Fukushima Daiichi plant’s operator, repeatedly hailed the extension of electrical wires to the plant, spoke of resuming electrically operated cooling systems and offered assurances that the situation would not get worse.

But late last week, three workers in a building next to Reactor No. 3 were injured when they stepped in contaminated water. Radioactive water was later discovered at two other reactors, making some areas of the reactor buildings dangerous for workers to approach.

Some of that water in the reactor structures also appears to be leaking out through damaged pipes or vessels, forming highly contaminated pools at the bottom of the turbine buildings adjacent to the reactors. On Tuesday, workers were forced to divert their attention to readying sandbags and pumps after the contaminated water was discovered in a tunnel leading close to the sea.

Compounding the matter, the government said Tuesday that the recent discovery of plutonium in the soil at the plant provided new evidence that at least one reactor was experiencing melting of its nuclear fuel, as happened in the early days of the crisis.

While the source of the plutonium found at the plant was unclear, all three kinds of nuclear fuel at the complex could leak plutonium.

Fresh signs of radiation leaks have raised questions about the sustainability of the government’s feed-and-bleed approach.

One major problem, said Murray E. Jennex, an associate professor at San Diego State University with 20 years of experience in examining nuclear containment structures, was that all the water the Japanese were spraying had soaked important machinery like generators and pumps, further hampering efforts to restore the reactors’ electricity supply. The use of helicopters in the first week to drop water on the rectors from above was especially ineffective in hitting the target and may have done more harm than good, he said.

“They dumped water all over the place,” he said. “They keep on generating more contamination. That’s the consequence of doing it. They got water on things that shouldn’t be wet.”

Hiroto Sakashita, an associate professor in nuclear reactor thermal hydraulics at Hokkaido University, said that though the fuel rods in the nuclear reactors had already lost over 99 percent of their heat, they were still giving off enough heat to evaporate an estimated 200 tons of water a day.

And the remaining heat, from isotopes with long half-lives, will take years to cool. “They will just have to keep on pouring and pouring,” Mr. Sakashita said, “but contaminated water will keep leaking out.”

“Handling this situation is getting increasingly difficult,” he said.

Another hurdle workers face, of course, is to keep pumping enough water to cool the fuel rods, while at the same time trying to minimize the overflow of contaminated water. Tokyo Electric is also struggling to replace workers at the crippled plant, who must be cycled out as they approach a cumulative radiation exposure limit set by the Japanese government.

The company is leaning on its contractors to provide more workers, sometimes offering many times normal wages for the increasing risks of working at Fukushima, according to local news reports.

The risks that Japan could export its nuclear problems by allowing radioactive contaminants to get into the air and sea are among the reasons why the government and Tokyo Electric have enlisted the help of experts from France, the United States and elsewhere to make sure conditions do not spiral out of control.

On Tuesday, Peter B. Lyons, a senior United States nuclear energy official, said the Energy Department was preparing a shipment to Japan of radiation-hardened robots, and the personnel to demonstrate how to use them.

In an admission of how long the cooling process may take, Hidehiko Nishiyama, deputy director general of the Nuclear and Industrial Safety Agency, Japan’s nuclear regulator, said late Tuesday: “We will have to continue cooling for quite a long period. We should be thinking years.”

Kuni Yogo, a former atomic energy policy planner in the Japan Science and Technology Agency, said: “There is some trial and error, but this is the beginning of a three- to five-year effort.”

Matthew L. Wald contributed reporting from Washington.

Source

Comments are closed, but trackbacks and pingbacks are open.