Fukushima’s crippled reactors: the risky plan to move fuel rods – World – CBC News.
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 highly radioactive spent 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
Workers at Fukushima Daiichi plan to remove more than 3,100 fuel rod assemblies from four reactor buildings.
Tokyo Electric Power Company officials say 80 of those assemblies are cracked — 70 in the reactor one building. They say holes and cracks in the damaged assemblies could cause radioactive particles to leak out.
Six teams of six workers will operate the crane to move the assemblies to the special containers. Each team can only work for two hours a day — they rotate to keep the operation moving, to minimize radiation exposure.
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.
It has also held back key information and stumbled from problem to problem over the past two-and-a-half 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.
The fuel rods to be removed over the next 12 months or so are mostly in 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 202 unused. Another roughly 1,500 assemblies in the three other reactors are to be removed as well.
Workers spent months shoring up the structure and the pool, fearing another strong quake could trigger a catastrophe.
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.
Yamagishi admits engineers don’t know exactly how many assemblies have been damaged. The current estimate is that 80 have cracks.
“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.”
TEPCO workers have already removed a good amount of debris, 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, and stabilized the building.
- Crippled Fukushima reactor to get ice wall
- Removal of fuel rods begins at Fukushima Daiichi nuclear plant
They’ve also successfully removed two unused rod assemblies. This week they began using the specially constructed crane to extract the fuel units one-by-one, keeping them underwater as they move them into specially-designed containers and then to another location on site.
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 none in their industry has faced before, and they’ll 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 begain 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.”