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Why Fukushima Is a Greater Disaster than Chernobyl
by Robert Alvarez
Why Fukushima Is a Greater Disaster than Chernobyl by Robert Alvarez
With the world’s worst nuclear power disaster well over a year in the past, 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 US 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 US 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 would result in overheating and cause melting, igniting the fuel’s 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. As one of the most dangerous materials in the world, spent reactor fuel poses significant long-term risks and requires isolation in a geological disposal site that can protect the human environment for tens of thousands of years.
Several pools are now completely open to the atmosphere and could collapse from another powerful earthquake.
Fukushima and Chernobyl
It’s 26 years since the Chernobyl reactor exploded and caught fire, releasing enormous amounts of radioactive debris. That accident revealed the folly of not having an extra barrier of thick concrete and steel surrounding the reactor core, something required for modern plants in the US, 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, accumulating in biota and the human food chain for many decades. When it enters the human body, about 75% 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.
Studies of chronic exposure to Cs-137 show an alarming rate of heart problems…
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 in cesium-137—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 northeast Japan. Thirteen earthquakes of magnitude 4.0–5.7 occurred off the coast of Honshu between April 14 and 17. This has been the norm since the first quake and tsunami hit the site on March 11 of 2011. Larger quakes are expected, closer to the power plant.
Tokyo Electric Power Company (TEPCO) recently revealed plans to remove 2,274 spent fuel assemblies from the damaged reactors. That will probably take at least a decade to accomplish. The first priority will be removal of the contents in Pool No. 4. This pool is structurally damaged and contains about 10 times more Cs-137 than was released at Chernobyl. Removal of spent fuel from the No. 4 reactor is optimistically expected to begin at the end of 2013. A significant amount of construction to remove debris and reinforce the structurally-damaged reactor buildings, especially the fuel-handling areas, will be required.
Furthermore, it is not safe to keep 1,882 spent fuel assemblies containing ~57 million curies of long-lived radioactivity, including nearly 15 times more Cs-137 than released at Chernobyl, in the elevated pools at reactors 5, 6, and 7 (which did not experience melt-downs and explosions).
The cycle’s still open
The main reason why there is so much spent fuel at the Da-Ichi site is that the fuel was supposed to be sent to the Rokkasho reprocessing plant, which has experienced 18 lengthy delays throughout its construction history. Plutonium and uranium were to be extracted from the spent fuel there, with the plutonium to be used as fuel at the Monju fast breeder reactor. That would, it is said, “close” the nuclear fuel cycle.
After several decades and billions of dollars, the United States effectively abandoned the “closed” fuel cycle 30 years ago for reasons of cost and nuclear non-proliferation. Over the past 60 years, the history of fast reactors using plutonium is littered with failures, the most recent being the Monju project in Japan. Monju was cancelled in November of last year, dealing a fatal blow to the dream of a “closed” nuclear fuel cycle in Japan.
The stark reality, if TEPCO's plan is realized, is that nearly all of the spent fuel at the Da-Ichi site, containing some of the largest concentrations of radioactivity on the planet, will remain indefinitely in vulnerable pools. TEPCO wants to store the spent fuel from the damaged reactors in the common pool, and only to resort to dry-cask storage when the common pool’s capacity is exceeded. At this time, the common pool is at 80% storage capacity and will require removal of fuel to make room. TEPCO’s plan is to minimize dry cask storage as much as possible and to rely indefinitely on vulnerable pool storage. Senator Wyden finds that TEPCO’s plan for remediation carries extraordinary and continuing risk. He sensibly recommends that retrieval of spent fuel in existing on-site spent fuel pools to safer storage in dry casks should be a priority.
Given these circumstances, a key goal for the stabilization of the Fukushima-Dai-Ichi site is to place all of its spent reactor fuel into dry, hardened storage casks. This will require about 244 additional casks at a cost of about $1 million per cask. To accomplish this goal, an international effort is required – something that Wyden has called for. As we have learned, despite the enormous destruction from the earthquake and tsunami at the Dai-Ichi Site, the nine dry casks and their contents were unscathed. This is an important lesson we should not ignore.
Robert Alvarez is a Senior Scholar at the Institute for Policy Studies in Washington DC specializing in energy, environment and national security issues. Between 1993 and 1999, Mr. Alvarez served as Senior Policy Advisor to the U.S. Secretary of Energy.
[22 aug 12]