I want to put together here some discussions of Fukushima and the issues it raises.
APRIL 24, 2012
Warning Signs for the US
Why Fukushima is a Greater Disaster Than Chernobyl
by ROBERT ALVAREZ
In the aftermath of the world’s worst nuclear power disaster, the news media is just beginning to grasp that the dangers to Japan and the rest of the world posed by the Fukushima-Dai-Ichi site are far from over. After repeated warnings by former senior Japanese officials, nuclear experts, and now a U.S. Senator, it is sinking in that the irradiated nuclear fuel stored in spent fuel pools amidst the reactor ruins may have far greater potential offsite consequences than the molten cores.
After visiting the site recently, Senator Ron Wyden (D-OR) wrote to Japan’s ambassador to the U.S. stating that, “loss of containment in any of these pools could result in an even greater release than the initial accident.”
This is why:
- * Each pool contains irradiated fuel from several years of operation, making for an extremely large radioactive inventory without a strong containment structure that encloses the reactor cores;
- * Several pools are now completely open to the atmosphere because the reactor buildings were demolished by explosions; they are about 100 feet above ground and could possibly topple or collapse from structural damage coupled with another powerful earthquake;
- *The loss of water exposing the spent fuel will result in overheating can cause melting and ignite its zirconium metal cladding – resulting in a fire that could deposit large amounts of radioactive materials over hundreds of miles.
Irradiated nuclear fuel, also called “spent fuel,” is extraordinarily radioactive. In a matter of seconds, an unprotected human one foot away from a single freshly removed spent fuel assembly would receive a lethal dose of radiation within seconds. As one of the most dangerous materials in the world, spent reactor fuel poses significant long-term risks, requiring isolation in a geological disposal site that can protect the human environment for tens of thousands of years.
It’s almost 26 years since the Chernobyl reactor exploded and caught fire releasing enormous amounts of radioactive debris. The Chernobyl accident revealed the folly of not having an extra barrier of thick concrete and steel surrounding the reactor core that is required for modern plants in the U.S., Japan and elsewhere. The Fukushima Dai-Ichi accident revealed the folly of storing huge amounts of highly radioactive spent fuel in vulnerable pools, high above the ground.
What both accidents have in common is widespread environmental contamination from cesium-137. With a half-life of 30, years, Cs-137 gives off penetrating radiation, as it decays. Once in the environment, it mimics potassium as it accumulates in biota and the human food chain for many decades. When it enters the human body, about 75 percent lodges in muscle tissue, with perhaps the most important muscle being the heart. Studies of chronic exposure to Cs-137 among the people living near Chernobyl show an alarming rate of heart problems, particularly among children.
As more information is made available, we now know that the Fukushima Dai-Ichi site is storing 10,833 spent fuel assemblies (SNF) containing roughly 327 million curies of long-lived radioactivity About 132 million curies is cesium-137 or nearly 85 times the amount estimated to have been released at Chernobyl.
The overall problem we face is that nearly all of the spent fuel at the Dai-Ichi site is in vulnerable pools in a high risk/consequence earthquake zone. The urgency of the situation is underscored by the ongoing seismic activity around NE Japan in which 13 earthquakes of magnitude 4.0 – 5.7 have occurred off the NE coast of Honshu in the last 4 days between 4/14 and 4/17. This has been the norm since the first quake and tsunami hit the site on March 11th of last year. Larger quakes are expected closer to the power plant….http://www.counterpunch.org/2012/04/24/why-fukushima-is-a-greater-disaster-than-chernobyl/
Dr. Helen Caldecott on radiation dangers