The Fukushima Nuclear Disaster Is Far From Over
Spent reactor fuel, containing roughly 85 times more
long-lived radioactivity than released at Chernobyl, still sits in pools
vulnerable to earthquakes.
More than a year after the Fukushima nuclear power disaster
began, the news media is just beginning to grasp that the dangers to Japan and
the rest of the world are far from over. After repeated warnings by former
senior Japanese officials, nuclear experts, and now a U.S. senator, it's
sinking in that the irradiated nuclear fuel stored in spent fuel pools amidst
the reactor ruins pose far greater dangers than the molten cores. This is why:
• Nearly all of the 10,893 spent fuel assemblies sit in pools vulnerable to future earthquakes, with roughly 85 times more long-lived radioactivity than released at Chernobyl
• Several pools are 100 feet above the ground and are
completely open to the atmosphere because the reactor buildings were demolished
by explosions. The pools 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 and can cause melting and ignite its zirconium metal cladding
resulting in a fire that could deposit large amounts of radioactive materials
over hundreds, if not thousands of miles.
This was not lost on Senator Ron Wyden (D-OR), who after
visiting the site on April 6, wrote to Japan's U.S. ambassador, Ichiro
Fujusaki, that "loss of containment in any of these pools... could result
an even larger release of radiation than the nuclear accident."
The urgency of the situation is underscored by the ongoing seismic activity where 13 earthquakes of magnitude 4.0-5.7 have occurred off the northeast coast of Japan between April 14 and 17. This has been the norm since the first quake and tsunami hit the Dai-Ichi site on March 11 of last year. Larger quakes are expected closer to the power plant.
Spent nuclear fuel is extraordinarily radioactive and must
be handled with great care. In a matter of seconds, an unprotected person 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
on the planet, spent reactor fuel requires permanent geological isolation to
protect humans for thousands of years.
It's been 26 years, since the Chernobyl reactor exploded and
caught fire releasing enormous amounts of radioactive debris -- seriously
contaminating areas over a thousand miles away. Chernobyl 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 operating several nuclear
power plants in a high consequence earthquake zone while 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 and can remain dangerous
for hundreds of years. Once in the environment, it mimics potassium as it
accumulates in the food chain. When it enters the human body, about 75 percent
lodges in muscle tissue, with, perhaps, the most important muscle being the
heart.
Last week, Tokyo Electric Power Company (TEPCO) 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 cesium-137 than released at Chernobyl. Removal of
SNF 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.
Also, 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 meltdowns and explosions.
The main reason why there is so much spent fuel at the
Da-Ichi site is that the plan to send it off for nuclear recycling has
collapsed. It was supposed to go to the incomplete Rokkasho reprocessing plant,
just south of the Fukushima nuclear site, where plutonium would be extracted as
a fuel for "fast" reactors. This scheme is based on long discredited
assumptions that world uranium supplies would be rapidly exhausted and that a
new generation of "fast" reactors, which held the promise of making
more fuel than they use, would be needed. Over the past 20 years the Rokkasho's
costs have tripled along with 18 major delays. World uranium supplies are far
from depleted. Moreover, in November of last year, Japan's "fast"
reactor project at Monju was cancelled for cost and safety reasons -- dealing a
major blow to this whole scheme.
The stark reality, if TEPCO's plan is realized, is that
nearly all of the spent fuel at the Da-Ichi 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 percent
storage capacity and will require removal of SNF to make room. TEPCO's plan is
to minimize dry cask storage as much as possible and to rely indefinitely on
vulnerable pool storage. Sen. Wyden finds that that TEPCO's plan for
remediation "carries extraordinary and continuing risk" and sensibly
recommends that "retrieval of spent fuel in existing on-site spent fuel
pools to safer storage... in dry casks should be a priority."
Despite the enormous destruction from the earthquake and
tsunami, little attention was paid to the fact that the nine dry spent fuel
casks at the Fukushima Da-Ichi site were unscathed. This is an important lesson
we cannot afford to ignore.
huffingtonpost
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