The devastating 9.0 earthquake that rocked northern Japan and the ensuing tsunami have already claimed an estimated 10,000 victims. But the worst may be yet to come. Experts estimated that the next 48 hours will be crucial in determining whether Japan's nuclear disaster unfolds like the U.S. Three Mile Island accident in 1979 or like the meltdown at the Ukraine's Chernobyl plant in 1986.
Two dozen Japanese workers at the Fukushima Daiichi Nuclear Power Station along with17 U.S. crew members of the USS Ronald Reagan have already been decontaminated for radiation exposure. If offshore winds shift, as predicted by Japanese weather forecasters, then airborne radioactive clouds could be headed for the Japanese mainland in the next 24 hours.
Observers said the biggest threat is plutonium fuel. Only one Fukushima
reactor uses plutonium-enriched uranium fuel known as MOX, or "mixed oxide" fuel. A hydrogen explosion at the No. 3 reactor on Sunday (March 13) injured 11 workers. So far, Japanese officials said the
containment vessel in the No. 3 reactor appears to be holding. But
it could take weeks or even months before the MOX fuel cools to levels that no
longer threaten public safety.
"If there is a large-scale release of plutonium into the air this could become the worst nuclear disaster in history," predicted Ira Helfand, a member of the board of Physicians for Social Responsibility. "So far, the venting of radioactive steam has been blown out to sea, but tomorrow [March 15] the wind is forecast to shift to northeast which means any radiation released tomorrow will be blown straight toward Tokyo, which is less than 150 miles away."
A release of deadly plutonium would require heightened precautions to protect Japanese citizens, particularly if winds shift. Helfand said these would include staying indoors and testing water and foods supplies. "Most of the exposure to people at Chernobyl, for instance, was from
children drinking contaminated milk that had not been tested," Helfand said, resulting in high rates of thyroid cancer in children.
Making matters worse, a third explosion, this one inside Fukushima's No. 2 reactor, was
reported Tuesday morning Japan time. Tokyo Electric Power Co. confirmed that radiation from the blast likely leaked after the No. 2 reactor's containment vessel was damaged, Kyodo news service reported.
Despite safety concerns that have prompted the use of backup systems like buried diesel fuel tanks for secondary generators at U.S. nuclear plants, experts are baffled at the lack of adequate backup systems in Japan. The lack of functioning secondary generators, for example, has led directly to cooling problems linked to the three explosions at Fukushima.
Those aging boiling-water reactors were designed by General Electric. The inner reactor core--which generates heat using nuclear fission in a controlled chain reaction--boils circulating water which in turn drives a steam turbine to generate electricity. The heated water is then circulated through cooling pipes which, like a car radiator, cool the water before it re-enters the reactor.
When the earthquake struck last Friday about 80 miles off the coast of Sendai, Japan's nuclear reactors automatically shut down. Control rods were then inserted to dampen the fuel rods and stop the reactor's chain reaction. Electric pumps were supposed to continue running to circulate the hot water through cooling pipes, allowing the reactors to go into an orderly shut-down mode.
Then the power grid went down. Backup generators kicked on when the quake struck to keep cooling water circulating.
What I have not seen anyone attempt to explain is why it takes such an incredibly long time to get the reactor cooled down even though supposedly the reaction was halted immediately. Even when the circulation system is working normally it sounds like it takes a very long time? And this article said used fuel rods are placed in a pool for "10-20 years" just to cool down? It can't possibly take that long but must be primarily a safe storage area until they get around to shipping the used rods to safe storage.
@jarg: Agreed. Thorium seems to be a potential winner. The Indians have a working Th reactor. It has been suggested that "Obama could kill fossil fuels overnight with a nuclear dash for thorium," and could put "an end to our dependence on fossil fuels within three to five years." http://en.wikipedia.org/wiki/Thorium#Thorium_as_a_nuclear_fuel
David Stonier-Gibson http://splatco.com
Brilliant article on a terrible subject. Let's hope that the prevailing winds continue to blow radioactive fumes to sea. Before reading your article, Colin, I had thought that Tokyo was "safe" from contamination. Now I am not so sure. Time will tell. Let's hope that it plays in Japan's favor this time.
These radioactive isotopes are really heavy compared to water or air, shouldn't they settle to ground very quickly? The greater danger would be they would seep into groundwater and become part of the food cycle.
There have been many 'reports' about the nuclear power plant problems in Japan as a result of the MAJOR earthquake/tsunami double whammy Japan has suffered. However, I must give kudus to Colin on this article for his clarity in explaining the failures. It is hard to get some details out of the mainstream press.
While one can always bemoan the fact that the failures occurred, as well as the reasons for them, in general nuclear power has worked well in Japan for nearly 40 years.
David Patterson, known for his pioneering research that led to RAID, clusters and more, is part of a team at UC Berkeley that recently made its RISC-V processor architecture an open source hardware offering. We talk with Patterson and one of his colleagues behind the effort about the opportunities they see, what new kinds of designs they hope to enable and what it means for today’s commercial processor giants such as Intel, ARM and Imagination Technologies.