(Corrects number of assemblies in fifth paragraph in story originally published Oct. 18.)
The first removal of nuclear fuel rods next month from the stricken Fukushima atomic station should be successful based on findings that the rods -- each about twice the average weight of a sumo wrestler -- appear undamaged from an explosion at the site almost three years ago.
That’s the view of Lake Barrett, a former U.S. Nuclear Regulatory Commission official appointed last month as an adviser to Tokyo Electric Power Co. (9501), the operator of the wrecked Fukushima Dai-Ichi nuclear plant.
“There’s no indication based on sampling of the water that the fuel has been damaged in any significant way” according to radiation readings, said Barrett, who led Three Mile Island’s cleanup operations for four years after the 1979 accident at that plant in the U.S. “There’s a high confidence that the defueling of the pool can go in a normal way.”
Pulling out the fuel rods is an early milestone in Tokyo Electric’s decommissioning of the plant, which is spread over 864 acres or about 490 soccer fields on the Pacific coast northeast of Tokyo. Removal of the rods will run through 2014, while the cleanup and decommissioning of the plant is expected to take as long as 40 years. It will include removing hundreds of tons of fuel that melted down in the core of three other reactors, a task never before attempted.
The 1,533 fuel rod assemblies sit in a spent fuel pool about 12 meters (40 feet) deep, which serves to cool the uranium fuel. The pools are built out of reinforced concrete several feet thick that, combined with a steel liner, acts as a radiation shield. The pool is on the fifth floor of reactor building 4, which was heavily damaged by an explosion after the earthquake and tsunami in March 2011. That raised concern the rods may not be intact and too dangerous to remove.
Statue of Liberty
Tokyo Electric, known as Tepco, removed two rods from the cooling pool during a July 2012 test and found no breakage or large-scale corrosion, suggesting they escaped damage from the explosion, Mayumi Yoshida, a Tepco spokeswoman, said.
While the decommissioning is daunting by time, complexity and cost -- estimated at 1 trillion yen ($10 billion) though Tepco said it could rise further to a “staggering” amount -- even the preparation to remove the rods has been monumental.
Tepco has built a support structure around the building using 4,000 metric tons of steel, more than 142 times the metal in the Statue of Liberty. The structure covers the space of about five National Basketball Association courts, completely surrounding the five-story No. 4 reactor building.
“It’s a uniquely designed cantilever, so it doesn’t put any load on the building,” Barrett said. “It’s not attached to the building: it has its own foundation and its own strength.”
The fuel rods would be removed by a crane operator on a platform above the pool, guiding the crane by sight, though binoculars may be used to check identification numbers printed on the rods, Barrett said.
Each rod is 4.5 meters (15 feet) long and weighs 300 kilograms (661 pounds). Once pulled from the pool they are placed in a portable air-cooled cask that takes 22 rods. It’s then transported to a cooling pool elsewhere in the plant where the fuel can be stored more securely, Yoshida said.
It hasn’t been decided where the fuel will eventually be taken for storage, Yoshida said. She said she couldn’t provide additional details about when the removal would begin, citing treaties aimed at reducing the risk of terrorist attacks.
Removing the fuel from the wrecked building will significantly reduce the risk of serious accidents at the site, Gregory Jaczko, a former chairman of the U.S. Nuclear Regulatory Commission, said last month in a phone interview.
“Getting that fuel out of that pool is extremely important because the integrity of the building is obviously damaged,” he said. “It’s not a trivial task.”
While Tepco should expect minimal difficulties during the fuel removal, its handling of irradiated water at the site remains an unnecessary drain on resources and makes the plant increasingly vulnerable to leaks, said Barrett.
The Fukushima site now has more than 380,000 metric tons of toxic water stored in more than 1,000 tanks. Those levels are rising at a rate of 400 tons a day as groundwater seeping into basements mixes with cooling water that has been in contact with highly radioactive melted reactor cores.
Tepco needs to devise a plan that, with government and community support, will allow it to release water into the ocean after treating it to bring contamination levels down to allowable levels for discharge, Barrett said.
Measures taken after a leak of about 300 tons of irradiated water has had the unintended consequence of increasing the volumes of toxic water that Tepco has to manage, Barrett said.
Before that leak, which was detected on Aug. 19, it was company policy to leave the valves on the cement barriers around the tank open to allow for the drainage of rainwater, Yoshida said. Crews were instructed to close the valves if a leak was detected, she said.
After the leak was found to have continued for weeks without detection, Trade Minister Toshimitsu Motegi issued an Aug. 26 order to keep the rainwater valves shut, Yoshida said. The rainwater has now been contaminated by atmospheric radiation at the plant site, Japan’s regulator told Tepco to store the water rather than allowing it to drain, she said.
“Tepco engineers and operators were trying to do a good thing, but in reality they caused more of an environmental impact than if they hadn’t,” Barrett said. “Part of the problem is they have no overall water-management plan.”
To contact the reporter on this story: Jacob Adelman in Tokyo at firstname.lastname@example.org