Tepco Faces Risky Cleanup Stage

Nov. 7, 2013 11:52 a.m. ET

A Tepco employee wearing protective suit and mask walks past radioactive water storage tanks Thursday. Associated Press

TOKYO—Operators of the Fukushima Daiichi nuclear-power plant this month will begin a potentially hazardous operation to remove fuel rods from one of the reactor units, a critical step in what is expected to be a decadeslong cleanup of the site of one of the worst nuclear-energy accidents in history.
Tokyo Electric Power Co. 9501.TO -1.14% Tokyo Electric Power Co. Inc. Japan: Tokyo ¥520 -6 -1.14% Nov. 8, 2013 3:00 pm Volume : 26.08M P/E Ratio 3.62 Market Cap ¥845.29 Billion Dividend Yield N/A Rev. per Employee ¥129,550,000 11/07/13 Tepco Prepares to Remove Fuel … 11/07/13 Fukushima Watch: Daiichi Plant… 10/30/13 Fukushima Watch: Watchdog Appr… More quote details and news » 9501.TO in Your Value Your Change Short position , known as Tepco, plans to transfer 1,533 metal casings holding nuclear-fuel pellets from their precarious storage pool—130 feet above the ground in one of the plant’s reactors—to a common pool serving all six reactors.
Tepco is touting the removal of the 550-lb assembly units as a milestone in what has so far been a troubled cleanup process. Since the March 2011 quake and tsunami crippled the plant, Tepco has had several mishaps, from brief power failures—caused in one case by rats gnawing through cables—to recent disclosures that storage containers holding contaminated water have sprung leaks, allowing at least some radiation to reach the ocean waters adjacent to the plant.
The operation at the No. 4 reactor will take more than a year to complete. Each of the casings holds 60 to 74 metal-clad rods, which are filled with the fuel pellets that power a nuclear reactor. Because exposure to the air can cause the radioactive material to heat up, and could in some cases lead to a sustained nuclear reaction, the casings are kept in pools of cool water.
Still, the most difficult work in the cleanup lies ahead, experts say. While the building that houses the No. 4 reactor sustained structural damage that complicates its cleanup, nuclear fuel in three other reactors overheated to the point of meltdown. To date, no one is certain of the state of the nuclear fuel inside those reactors because they remain too contaminated to allow workers nearby, even with protective clothing.
To prepare for removal of the fuel assemblies, Tepco has done extensive rebuilding on the structure that houses the reactor.
Supported by a new steel framework, cranes will lift each fuel-assembly unit and put it in a container in the storage pool. The container, weighing about 91 metric tons when full, will then be sealed and lifted out of the pool and placed on a truck. Then it will be taken to the common fuel pool that already holds 6,375 such assemblies.
The removal of the fuel assemblies is “the right thing to do, because keeping the fuel up there is quite risky,” says Hiromitsu Ino, professor emeritus of nuclear engineering at the University of Tokyo.
Among the risks he and other experts cite is the possibility that a container being used to move the units falls and breaks apart, exposing the fuel to the air.
“Handling spent fuel involves considerable risks,” said Shunichi Tanaka, chairman of Japan’s Nuclear Regulation Authority, which was created after the Fukushima accident to provide greater oversight of the industry. “They must be handled one by one, very carefully.”
Hiroaki Koide, a nuclear scientist working at the University of Kyoto and a prominent opponent of nuclear power, said last month he was very worried about an accident, given the magnitude of the task. “I’m worried about whether Tepco can treat all the 1,331 [spent-fuel] assemblies without any problem and how long it will take,” he said.
Tepco said that it has taken extra precautions to protect the fuel. Even if a quake causes a power failure while the assemblies are being moved, a locking device would prevent any fall of the container.
“We have removed spent fuels many times. Therefore, we don’t think we are going to be doing anything that is very dangerous,” Akira Ono, the head of the Fukushima plant, told reporters on a tour of the site Thursday.
Others have called for the Japanese government to take a more direct role, with a panel from the ruling Liberal Democratic Party recommending more oversight and that the cleanup operation be split off from the utility’s daily operations.
While there are potential hazards in the fuel removal, they shouldn’t be overstated, some nuclear experts say.
“There are always risks with any industrial operations with hazardous materials,” says Lake Barrett, a U.S.-based nuclear consultant who was the senior regulatory official in charge of the cleanup of the Three Mile Island nuclear plant in Pennsylvania. He has recently advised Tepco on the cleanup.
Mr. Barrett said that even if there were an accident, most of the fuel assemblies are of low energy, since they have already been in use, and are therefore unlikely to heat to a critical point.
“A fuel assembly in this state has the heat output of a few toasters. Worldwide experience with a few dropped or damaged fuel assemblies has not resulted in any off-site impact,” he said.
Amid global concerns about the fate of the plant, Mr. Barrett is one of many foreign experts being brought in to help advise on the cleanup. Tepco has also brought in experts from the International Atomic Energy Agency and the U.S.-based Institute of Nuclear Power Operations.
Write to Mari Iwata at mari.iwata@wsj.com and William Sposato at william.sposato@wsj.com

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