19 Décembre 2013
December 18, 2013
Japan is incapable of safely decommissioning the devastated Fukushima No. 1 nuclear plant alone and must stitch together an international team for the massive undertaking, experts say.
However, only halting progress has been made so far.
Unlike the United States and some European countries, Japan has never decommissioned a full-fledged reactor. Now it must do so at Fukushima No. 1. When the reactors melted down after the 2011 earthquake and tsunami, what is ordinarily a technically challenging operation became much more complex.
The cloud over Japan’s capacity to get the decades-long job done has further undermined the image of the nuclear industry with the public. Opinion surveys show a majority of people are opposed to restarting the 50 reactors that were put offline for safety and other checks since the disaster started. The nation has been forced to import oil and gas to meet its power needs, burdening an already feeble economy.
“Even for the U.S. nuclear industry, such a cleanup and decommissioning would be a great challenge,” said Akira Tokuhiro, a University of Idaho professor of mechanical and nuclear engineering who is among those calling for a larger international role at the Fukushima facility.
Decommissioning a nuclear power plant normally involves first bringing the reactor cores to stable shutdown, and then eventually removing them for long-term storage. It is a process that takes years. Throughout, radiation levels and worker exposure must be monitored.
At Fukushima No. 1, there is the daunting challenge of taking out cores that suffered meltdown, which is the most dangerous type of nuclear power damage. The exact location of the melted fuel within the reactor units isn’t known and needs to be ascertained so their condition can be analyzed. That will require development of nimble robots capable of withstanding high radiation.
The lack of experts is worse at the regulatory level. The tally is zero.
The Nuclear Regulation Authority has no one devoted to decommissioning, said spokesman Juntaro Yamada, though it has experts dealing with the ongoing removal of fuel rods from reactor 4.
Its predecessor organization was criticized after the Fukushima disaster started for being too close to the nuclear industry, so the members chosen for the new agency launched last year don’t have direct ties to the industry to ensure their objectivity.
The government-funded Nuclear Energy Safety Organization, which is to be folded into the regulatory authority to beef up its expertise, has one expert on decommissioning, a person who studies overseas regulations on the process. The group mainly helps with routine nuclear plant inspections, but since the 2011 catastrophe has been involved with bringing Fukushima No. 1 under control.
In contrast, the U.S. Nuclear Regulatory Commission has 10 people devoted to decommissioning, including four project managers, four health physicists, and a hydrogeologist. It says it has the equivalent of more than 200 years of experience in decommissioning and has overseen the termination of 11 power reactors and 13 research reactors.
France has decommissioned nine reactors, and its regulatory agency has seven decommissioning experts at the national level, and 10 more at the local level.
Lake Barrett, a retired nuclear engineer who took part in decommissioning Pennsylvania’s Three Mile Island after the meltdown of its reactor core in 1979, was hired as a consultant by Tokyo Electric Power Co. He visits about once a year or so to give advice and is not assigned daily to the job.
The cleanup at Fukushima No. 1 will be more difficult than Three Mile Island because the damage is more extensive, involving three reactors instead of one, and more serious because of the greater damage from the bigger explosions.
Barrett said one reason he wanted to help in Fukushima was that Japanese engineers had helped out at Three Mile Island. He had asked about their whereabouts but got no answers. He fears they are all retired or working in other industries.
“The most challenging area is skilled nuclear engineers and managers that can plan, integrate and communicate effectively in Japanese,” he said.
Japan’s nuclear program started later than the U.S. and it has scrapped only a small test reactor. Five reactors are in various stages of decommissioning, including two experimental reactors and three commercial ones.
The furthest along is reactor 1 at the Tokai power station in Ibaraki Prefecture, 15 years into a planned 22-year process. About 70 experts are working on the decommissioning, but the experience gained with Japan’s oldest reactor is not directly transferable to Fukushima.
The decommissioning of two reactors similar to Fukushima’s began in 2009 at the Hamaoka nuclear plant in Shizuoka Prefecture, but it is in the early stages and is expected to take nearly 30 more years.
It took until last August, nearly 2½ years after the tsunami, for Japan to set up the International Research Institute for Nuclear Decommissioning, to bring together ideas, both inside and outside Japan, on the decommissioning process at Fukushima No. 1 and encourage communication.
Tokuhiro, who has more than 20 years in the nuclear design and safety fields, calls it a step in the right direction but too small, given the huge task at hand. The organization acknowledges much remains to be done, including responding to unprecedented challenges that will require the development of robotics and other new technology.
Tokuhiro is advocating the creation of an international team to help Japan, including those with experience at Three Mile Island and Chernobyl.
“It is clear that this very large undertaking requires an international effort,” he said. “It is in the spirit of a global nuclear energy partnership.