Fukushima's crippled reactors: the risky plan to move fuel rods
World watching extremely delicate operation by TEPCO utility with checkered track record
The thousands of people who punch in every day at what is arguably the world's most dangerous workplace are accustomed to facing risks.
But now workers at the crippled Fukushima Daiichi nuclear plant have embarked on their most precarious operation since the March 11, 2011, earthquake and tsunami triggered meltdowns and explosions at the facility.
On Monday, select crews from Tokyo Electric Power Company began removing hundreds of radioactive fuel rods from a cooling pool inside a rickety reactor building, a job that is unprecedented in scale, and where one wrong move could have disastrous consequences.
Fuel rod quick facts
TEPCO engineers have a plan to remove more than 1,500 fuel rod assemblies from a pool in Daiichi nuclear site's reactor four building.
Six teams of six workers will operate a specially constructed crane to move the assemblies into containers. Each team can only work for two hours a day to minimize radiation exposure.
The assemblies are being raised at the speed of one centimetre per second to avoid any further damage.
The amount of radioactive cesium-137 in the pool holding the fuel rod assemblies is said to be the equivalent of roughly 14,000 Hiroshima-sized atomic bombs.
"It's a totally different operation than removing normal fuel rods from a spent fuel pool," Shunichi Tanaka, the chairman of Japan's Nuclear Regulation Authority, said recently.
"They need to be handled extremely carefully and closely monitored. You should never rush or force them out, or they may break. I'm much more worried about this than I am about contaminated water."
TEPCO's checkered track record
But given that TEPCO has not exactly won over the Japanese public with its handling of the catastrophe, and that the amount of radioactive cesium-137 in the pool is said to be the equivalent of roughly 14,000 Hiroshima-sized atomic bombs, this next step is turning into a crucial test for the beleaguered utility as much as it is an engineering challenge.
Few in Japan or abroad seem convinced that TEPCO can pull this off, given the company's checkered track record.
This is the same utility, they point out, that used false inspection reports years ago to cover up faults at Fukushima Daiichi; that dismissed warnings in 2008 that a monster tsunami could engulf the plant; that waited weeks to admit meltdowns even happened in March 2011, and that waited many months to acknowledge radioactive water is leaking into the Pacific Ocean.
TEPCO executives have also held back key information, and stumbled from problem to problem over the past 2½ years.
In fact, TEPCO has performed so poorly that a task force for Japan's ruling Liberal Democratic Party is recommending it be split up so that the job of decommissioning the wrecked plant would be separated from the utility's power-generating role.
TEPCO workers are expected to spend the next 12 months removing fuel rods from reactor four, which was offline when Fukushima Daiichi was shaken by powerful tremors and swamped by towering waves.
In the subsequent hydrogen explosions and fires, debris rained down on the large pool that holds 1,533 fuel rod assemblies —1,331 used (and highly radioactive) and 202 unused. Another roughly 1,500 assemblies are held in the three other reactor buildings.
TEPCO spokesperson Tatsuhiro Yamagishi told CBC News that along with cesium-137 and cesium-134, the radioactive isotopes contained in the fuel include strontium-90, radium-226, uranium-235, and plutonium-239, which has a half-life of approximately 24,000 years.
Company officials recently revealed that 80 assemblies are damaged, 70 of them in reactor one building. They say holes and cracks in the assemblies could cause radioactive particles to leak out.
"We are managing different types of risks," he said. "We are evaluating each case right now."
John Froats, an associate professor and nuclear engineer in residence at the University of Ontario Institute of Technology, says those risks can probably be dealt with if handled carefully.
"The Fukushima Daiichi plant evolution is no doubt complicated by the plant damage and debris," he said. "These complications can be managed by careful inspection to understand the state of systems and equipment and the fuel, and then by careful planning of the step-by-step tasks that need to be achieved."
Workers spent months shoring up the reactor four structure and its pool, fearing another strong quake could trigger a catastrophe. Then they removed larger pieces of debris and checked some fuel rod assemblies to make sure they weren't corroded by the seawater that was used to cool the pool in the early days of the crisis.
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Last year, they successfully removed two unused rod assemblies. This week they began using a specially constructed crane to slowly transfer the assemblies one-by-one into containers, which will be hoisted out of the pool and taken to another storage location on the Daiichi site. They've installed cameras in the murky waters to monitor the progress and check for debris.
In a corporate video on the TEPCO website, a deep-voiced narrator cheerfully runs through a simplified version of the process.
"Moving the spent fuel out of the damaged reactor building and into safe, permanent storage lays the groundwork for moving forward with cleanup and remediation of the damaged reactor building," the video says.
In the video, TEPCO also calls the removal of the fuel rod assemblies from the reactor four building "a milestone" in the recovery of Fukushima Daiichi.
The world is watching
Certainly, it's a key part of the decades-long decommissioning process now underway, and perhaps key to the company's survival.
But while utility managers have no choice but to show they're up to the task, the reality is they're tackling a challenge no one in their industry has faced before, and they will be carrying out the work knowing people around the world will be watching with critical eyes.
Among the critics is Mitsuhiko Tanaka, a science journalist and engineer who helped build part of reactor four at Fukushima Daiichi (and who later admitted to helping cover up a manufacturing flaw with the unit).
As he sees it, "TEPCO is a selling-electricity company, not an engineering company.
"It is quite apparent that TEPCO doesn't have enough ability to cope with the problems in progress now. That's why [it] has made a lot of mistakes."
Tanaka, who calls the current state of the nuclear plant "hopeless," says that while the utility has plenty of experience in normal fuel removal work, this job is different because of the possibility that some of the rod assemblies have been damaged.
And although TEPCO spokespersons insist their inspections and those by outside experts confirm the reinforcement of the reactor building has made it seismically sound, Tanaka maintains the structure is still vulnerable.
"I think it is very dangerous," he says. "Furthermore, this very difficult work is going to be done in an earthquake-prone country."
TEPCO was given permission in late summer to take on the removal of the fuel rods. But just before the operation began U.S. Energy Secretary Ernest Moniz visited the facility to offer American help.
"The success of the cleanup also has global significance," Moniz said. "We all have a direct interest in seeing that the next steps are taken well, efficiently and safely."