Tokyo Electric Power Co. estimates the fight to stabilize its crippled Fukushima reactors will last through June, leaving them vulnerable to more aftershocks and radiation leaks, a person briefed on the utility’s plan said.
Engineers at Tokyo Electric rejected a proposal to flood reactors at the damaged plant, which could lower temperatures in days rather than months, according to the person, who asked not to be identified because he isn’t authorized to speak to the media. Instead, the utility is pumping in water and venting off steam, a method called “feed and bleed.”
Since the magnitude-9 quake and tsunami hit the Fukushima Dai-Ichi station on March 11, there have been hundreds of aftershocks, including one this week that disabled the plant’s power and cooling systems for almost an hour. As the crisis drags on, there’s the risk of new accidents, said Pierre Zaleski, a former member of the French Atomic Energy Commission.
“The major problem is these aftershocks,” said Zaleski, executive director at the Center for Geopolitics of Energy and Raw Materials at the University Paris Dauphine. “You never know if there are more aftershocks and containment may fail --maybe not completely -- but these structures have been weakened.”
Tokyo Electric is reluctant to flood its reactors because the move might generate bad publicity, the person said. Flooding would increase the amount of contaminated water that gets into the ocean and also raise the possibility of more hydrogen explosions inside the containment, the person said.
Heat Blocks Decommissioning
Workers can’t start the process of decommissioning the plant’s four crippled reactors until temperatures and pressure have been brought down. Cleaning up the disaster, which has forced the evacuation of hundreds of thousands of people living within 20 kilometers (12 miles) of the plant, could take decades and cost more than 1 trillion yen ($12 billion).
The primary danger at the plant is reactor No. 1, where temperatures and pressure are still high and the water level is low, the person said. Water levels inside the core of the reactor dropped yesterday, according to data released by Tokyo Electric, leaving 1.65 meters of fuel rods exposed to air, where they can heat up and melt, releasing radiation into the pressure vessel.
While Tokyo Electric’s plan for ending the crisis says getting exposed fuel rods covered with water again is one measure of stabilization, according to the person briefed on the document, the utility’s data shows pumping efforts have failed to raise the water level more than 20 centimeters in the 35 days since the disaster started.
Low Water Levels
The failure to raise water levels is part of the reason U.S. Nuclear Regulatory Commission Chairman Gregory Jaczko this week called the situation “static,” rather than stable. “Significant additional problems” could still occur at the plant, he said at a hearing of the Senate Environment and Public Works Committee on April 12.
A make-shift combination of fire hoses and pumps being used to cool the reactor isn’t providing enough water, according to the person. Temperatures that measured 204.5 degrees Celsius (400 degrees Fahrenheit) inside the vessel yesterday, or twice boiling point, cause the water to turn into steam, creating a sauna-like cooling system that’s less effective, the person said.
Flooding the space between the pressure vessel and the surrounding containment could bring temperatures down in days rather than months, according to the person.
Generators Move Uphill
Tokyo Electric said today it will move backup generators for the plant to higher ground away from the sea to ensure cooling systems aren’t disrupted by future tsunamis. They will be placed 20 meters (66 feet) above sea level, double the current height, according to the company.
The utility also said it discovered uranium in soil sampled at the power station. The levels of uranium-234, uranium-235 and uranium-238 are almost identical to those found in nature, and it is unlikely the uranium came from reactor fuel, Junichi Matsumoto, a spokesman for Tokyo Electric, told reporters at a news conference in Tokyo today.
While Tokyo Electric hasn’t announced a time line for resolving the crisis, the person said the utility drafted an internal document two weeks ago called the “Tepco Short/Medium/Long Range Recovery Plan” that aims to have the reactors stabilized by the end of June.
Tokyo Electric President Masataka Shimizu, speaking publically this week for only the second time since the disaster started, said a schedule for dealing with the crisis “will be presented soon.”
U.S., French Support
Shimizu spoke to reporters a day after a magnitude-6.6 temblor disrupted power at Fukushima for 50 minutes, setting back efforts to cool reactors at a plant already weakened by explosions and last month’s quake and tsunami.
“We’re studying a variety of ways to resolve the crisis and getting support from the U.S. and France,” Naoyuki Matsumoto, a Tokyo-based spokesman for the utility, said yesterday. He declined to comment on specific measures being considered.
Decision-makers at the utility are walking a tightrope between risks, said David Lochbaum, a nuclear safety engineer at the Union of Concerned Scientists in Washington D.C. Although flooding could cause weakened containment structures to break, a slower process also has drawbacks, he said.
“They’re getting back to a situation where they have more control,” he said, referring to progress that’s been made in restoring roads and power to the plant. “The downside is that a surprise or a curveball could cause things to get worse.”