Nukewatch Quarterly Summer 2016
By John LaForge
March 11 marked the fifth anniversary of the worst earthquake in Japanese history and the devastating tsunami that followed, smashing Japan’s northeastern coast, killing as many as 19,000 people and sparking the worst radiation catastrophe since Chernobyl. Crashing over a 30-foot seawall, tsunami waters flooded the Fukushima Daiichi nuclear complex, knocking out emergency cooling pumps and causing three reactors to overheat, melt, and burn their way through their steel containers. A series of hydrogen explosions blew apart the containment buildings surrounding the reactors resulting in the widespread dispersal of iodine-131, cesium-134, cesium-137 and other radioactive materials.
Fukushima cesium concentrating in zooplankton, anchor of the oceans’ food web
Scientists tracking radioactive materials leaked to the Pacific by the Fukushima disaster have given oceanographers surprising new information, notably that most of the contaminated surface water pushed by ocean currents east toward the United States from Japan, is “submerged to a depth of [1,312 feet] near to the International Date Line and then turns toward southwest.” This pattern of ocean currents was completely unknown prior to the new study, published in the journal Applied Radiation and Isotopes.
Japanese scientists, in collaboration with the European Commission’s Joint Research Centre traced the movement of cesium-134, and cesium-137 (known as radio-cesium) and collected samples of both zooplankton and suspended particles. Their study has found that “zooplankton contained higher amounts of radio-cesium than particulate matter as [zooplankton] consumes organic matter and thereby accumulates cesium.”
That the animals have more radio-cesium than the suspended particles is related to the process called bio-accumulation in which the plankton absorbs the isotope faster than it is excreted. The concentration of cesium is multiplied, increasing the ratio of the toxin in living tissue, as larger species eat smaller ones on up the food chain—something biologists have warned of since the spill began in March 2011.
Zooplankton are at the very bottom of the ocean food chain, and are eaten by everything from small animals and fish to huge whales. Many small animals and fish depend on zooplankton as their main source of food. The new study’s results are useful, the authors said, in order “to understand the uptake in the food chain and estimate impact on biosystems of future releases.”
While the Fukushima catastrophe is always called “second” in overall radiation release behind the 1986 Chernobyl disaster, the total amount of cesium-137 spewed by the Fukushima meltdowns may be two to four times greater than Chernobyl, according to a 2014 report by the Korea Atomic Energy Research Institute. —Sciencedaily.com, June 6, 2016
Unprecedented oceanic radiation release
This past March, Ken Buesseler, a marine radiochemist with the Woods Hole Oceanographic Institution reported: “More than 80 percent of the radioactivity from the damaged reactors ended up in the Pacific—far more than reached the ocean from Chernobyl… this event is unprecedented in its total release of radioactive contamination into the ocean.”
“The continued release of radionuclides from groundwater and leaking tanks at Fukushima… needs to be watched closely, as the character or mix of radionuclides is changing. One example is the higher levels of strontium-90 contained in groundwater and in storage tanks that are leaking into the ocean.”—www.WHOI.edu
Japan to use radioactive waste in building roads—lessons unlearned from US desert Southwest
The Environment Ministry on June 7 drew up a basic plan to use soil contaminated with radioactive substances in fallout from the Fukushima Daiichi triple meltdown releases to build roads.
Under the plan, soil tainted with relatively low radioactive cesium concentrations of up to 5,000 to 8,000 becquerels per kilogram will be used to form the base layer of roads.
This layer will then be covered with uncontaminated soil, asphalt and other material at a thickness of between 19 and 39 inches.
According to the ministry, covering radioactive soil with untainted material will minimize the health risk for residents living in nearby areas, as their annual radiation dose will be kept to 0.01 millisievert or less.
The ministry plans to launch a verification project in Minamisoma, Fukushima Prefecture, as early as this summer to test the use of contaminated soil as the base material for road construction.
Tainted soil in the prefecture, generated from decontamination work following the March 2011 accident …, will be kept in an interim storage facility near the nuclear reactor complex for final disposal at a site outside the prefecture within 30 years.
The interim facility, located in an area that straddles the towns of Okuma and Futaba, is believed to store up to 22 million cubic meters of contaminated soil. The latest plan will help the ministry facilitate the reuse of contaminated soil within and outside the prefecture to reduce the amount to be transferred to the final disposal site. —JIJI, The Japan Times, June 7, 2016
600-Ton Mass of melted fuel still not located in wreckage of three Fukushima reactors
Even 63 months since the triple melt-throughs, 600 tons of this molten uranium fuel—200 tons in each devastated reactor—is unaccounted for. Neither emergency response teams nor decommissioning authorities have been able to locate the mass of ferociously hot (radioactively and thermally) molten uranium fuel—which has to be constantly flooded with cooling water to prevent further melting.
As Energy Biz reported March 31, “The cooling water becomes radioactive and leaks out through damaged areas into the building basements, where it mixes with groundwater, increasing the volume of contaminated water.” Scientific American put it this way on March 1, “Groundwater flowing from a hill behind the crippled plant now mingles with radioactive materials before heading into the sea.”
“There is no end in sight for communities in Fukushima,” said Junichi Sato, Executive Director of Greenpeace Japan. “What started as a natural disaster turned into one of the worst industrial accidents in human history and a reminder that humanity must urgently turn its efforts toward safe, clean renewables,” Sato said.
One temporary fix—a $312 million refrigeration or “ice wall” dug into the ground uphill from the destroyed reactor complex—was switched on March 31 for the first time. The wall is supposed to divert groundwater to keep it from continually seeping through quake-damaged foundations under the reactor buildings. Flowing through the wreckage, the groundwater becomes highly radioactive by mixing with cooling water that is continually being poured onto the three masses of melted fuel. —Australian Broadcasting Corporation, May 24, 2016
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