But nuclear waste experts say the Japanese are literally playing with fire in the way nuclear spent fuel continues to be stored onsite, especially in reactor 4, which contains the most irradiated fuel -- 10 times the deadly cesium-137 released during the 1986 Chernobyl nuclear accident. These experts also charge that the NRC is letting this threat fester because acknowledging it would call into question safety at dozens of identically designed nuclear power plants around the U.S., which contain exceedingly higher volumes of spent fuel in similar elevated pools outside of reinforced containment.
Reactor 4: The Most Imminent Threat
The spent fuel in the hobbled unit 4 at Fukushima Daiichi not only sits in an elevated pool outside the reactor core's reinforced containment, in a high-consequence earthquake zone adjacent to the ocean -- just as nearly all the spent fuel at the nuclear site is stored -- but it's also open to the elements because a hydrogen explosion blew off the roof during the early days of the accident and sent the building into a list.
Alarmed by the precarious nature of spent fuel storage during his recent tour of the Fukushima Daiichi site, Sen. Ron Wyden, D-Oregon, subsequently fired off letters to Secretary of State Hillary Clinton, Secretary of Energy Steven Chu, NRC Chairman Gregory Jaczko and Japanese ambassador to the U.S. Ichiro Fujisaki. He implored all parties to work together and with the international community to address this situation as swiftly as possible.
A press release issued after his visit said that Wyden, a senior member of the U.S. Senate Committee on Energy and Natural Resources who is highly experienced with nuclear waste storage issues, believes the situation is "worse than reported," with "spent fuel rods currently being stored in unsound structures immediately adjacent to the ocean." The press release also noted the structures' high susceptibility to earthquakes and that "the only protection from a future tsunami, Wyden observed, is a small, makeshift sea wall erected out of bags of rock."
As opposed to units 1-3 at Fukushima Daiichi, where the meltdowns occurred, unit 4's reactor core, like units 5 and 6, was not in operation when the earthquake struck last year. But unlike units 5 and 6, it had recently uploaded highly radioactive spent fuel into its storage pool before the disaster struck.
Robert Alvarez, a nuclear waste expert and former senior adviser to the Secretary of Energy during the Clinton administration, has crunched the numbers pertaining to the spent fuel pool threat based on information he obtained from sources such as Tepco, the U.S. Department of Energy, Japanese academic presentations and the Institute of Nuclear Power Operations (INPO), the U.S. organization created by the nuclear power industry in the wake of the 1979 Three Mile Island accident.
What he found, which has been corroborated by other experts interviewed by AlterNet, is an astounding amount of vulnerably stored spent fuel, also known as irradiated fuel, at the Fukushima Daiichi site. His immediate focus is on the fuel stored in the damaged unit 4's pool, which contains the single largest inventory of highly radioactive spent fuel of any of the pools in the damaged reactors.
Alvarez warns that if there is another large earthquake or event that causes this pool to drain of water, which keeps the fuel rods from overheating and igniting, it could cause a catastrophic fire releasing 10 times more cesium-137 than was released at Chernobyl.
That scenario alone would cause an unprecedented spread of radioactivity, far greater than what occurred last year, depositing enormous amounts of radioactive materials over thousands of miles and causing the evacuation of Tokyo.
Nuclear experts noted that other lethal radioactive isotopes would also be released in such a fire, but that the focus is on cesium-137 because it easily volatilizes and spreads pervasively, as it did during the Chernobyl accident and again after the disaster at Fukushima Daiichi last year.
With a half-life of 30 years, it 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, including the heart.