Sometimes these man-made radionuclides are compared to naturally occurring radionuclides, such as potassium-40, which is found in bananas and other fruits. But this is a false comparison since most naturally occurring long-lived radioactive elements, commonly found in Earth’s crust, are very weakly radioactive.[9] Note that potassium-40 has a specific activity of 71 ten-millionths of a curie per gram. Compare that to 88 curies per gram for cesium-137 and 140 curies per gram for strontium-90.[10]
In other words, cesium-137 is 12 million times more radioactive than potassium-40. This is like comparing an atomic bomb to a stick of dynamite. Another highly radioactive fission product, strontium-90, releases almost 20 million times more radiation per unit mass than potassium-40. Which one of these would you rather have in your bananas?
Current radiation safety exposure standards use mathematical models to calculate the internal “committed” dose of radiation delivered by any given quantity of ionizing radiation. These models average the dose of ionizing radiation over the mass of the organ system or tissue mass where it occurs. This approach essentially ignores—and thus dismisses—the intensity of the given source and instead focuses upon the total amount of radiation released in the tissue.[11] In other words, the models equate the effects of a large amount of diffuse, naturally occurring radiation with that from a small, highly concentrated source as long as they both contain the same total amount of energy. If the total energy in a large bucket of warm water is equivalent to that in a tiny, burning piece of coal, does drinking the warm water have the same biological effect as swallowing the coal?
The amount of cesium-137 deposited per square kilometer (or square mile) of land defines the degree to which an area is classified as being too radioactive to work or live in. To get an idea of the extreme toxicity of cesium-137, consider how little of it is required to make a large area of land uninhabitable for more than a century.
The lands that were grossly contaminated by the destruction of the Chornobyl nuclear power plant are classified by the number of curies of radiation per square kilometer. Strict radiation-dose control measures were imposed in areas contaminated to levels greater than 15 curies per square kilometer of cesium-137. The total area of this radiation-control zone is huge: 10,000 square kilometers, or 3,861 square miles, which is nearly half the area of the state of New Jersey.[12]
The 1,100-square-mile uninhabitable exclusion zone that surrounds the destroyed Chornobyl reactor has greater than 40 curies of radioactivity per square kilometer, or 104 curies per square mile.
Consider again that one gram of cesium-137 has 88 curies of radioactivity. This means that as little as one-third of a gram of cesium-137, evenly distributed as smoke or a gas over an area of one square kilometer, will make that square kilometer into a radioactive exclusion zone. Less than two grams of cesium-137—a quantity less than half the weight of an American dime—if made a radioactive gas or aerosol and evenly distributed over an area of one square mile, will turn that square mile into a radioactive exclusion zone that will remain uninhabitable for one hundred to two hundred years. For example, the 1,317 square miles of Central Park in New York City can be made uninhabitable for more than a century by less than two grams of cesium-137.
Hard to believe, isn’t it? Remember, these nuclear poisons are lethal at the atomic level. There are roughly as many atoms in one gram of cesium-137 (4.39 x 1021 atoms) as there are grains of sand on all the beaches of the world. This means that if one gram of cesium-137 is evenly spread over a square mile, there will be about 1.42 quadrillion (1.42 x 1015) atoms of cesium-137 per square yard of the contaminated square mile. This works out to about 100,000 disintegrations per second per square yard within this square mile from cesium-137 recently released from a fuel rod inside a destroyed nuclear reactor. The number of atomic disintegrations per second will slowly decrease with time as the cesium-137 self-destructs.
Figure 5.3 illustrates the immense inventories of cesium-137, about 150 million curies, in the form of spent nuclear fuel, located at Indian Point nuclear power plant, which is forty-seven miles from New York City as the radioactive cloud flies. Many of the 104 U.S. commercial nuclear power plants have more than 100 million curies of cesium-137 in their spent-fuel pools. Note that 150 curies of cesium-137 is equal to about 1.7 million grams of cesium-137—a quantity many times greater than that contained within any of the spent pools sitting next to the destroyed reactors at Fukushima Daiichi.
It is now widely recognized that the nuclear reactors 1, 2, and 3 at Fukushima Daiichi all melted down and melted through their steel reactor vessels within a few days following the earthquake and tsunami of March 11, 2011. This was not made public by either TEPCO or the Japanese government until May 17, 2011, more than two months after the meltdowns and melt-throughs occurred. During these two months, TEPCO continually stated that it was “trying to prevent a meltdown” of the reactors and was not contradicted by Japanese government officials.[13]
The greatest amounts of highly radioactive gases and aerosols were released shortly after the meltdowns occurred. Approximately 80 percent of the radioactive material initially released by the reactors is believed to have traveled away from Japan, over the Pacific. However, the remaining 20 percent was dispersed over the Japanese mainland.
On March 11, the U.S. National Nuclear Security Administration offered the use of its NA-42 Aerial Measuring System to the Japanese government, and the National Atmospheric Release Advisory Center (NARAC) of the Lawrence Livermore National Laboratory stood up to provide atmospheric modeling projections. With the help of American technical means, Lawrence Livermore was able to produce detailed and timely estimates of the radiation plumes emanating from the destroyed reactors, and presumably these were given to the Japanese government.
Scientists at Lawrence Livermore have published a Power-Point of their computer models that includes a distinct image of the highly radioactive plume from Fukushima blowing south over the Tokyo metropolitan area on March 14, 2011. All the areas that the radioactive plume passed over were contaminated, but it appears that the heaviest contamination was deposited outside the metropolitan area, where rainfall occurred.[14]
Eight months after the disaster, the Japanese science ministry released a map detailing the fallout, which showed that 11,580 square miles (30,000 square kilometers)—equaling 13 percent of the Japanese mainland—had been contaminated with cesium-137. The official map does not indicate any cesium-137 contamination in the Tokyo metropolitan area, unlike an unofficial survey done at about the same time by Professor Yukio Hayakawa of Gunma University. Given the fact that the Japanese government and TEPCO denied for two months that any meltdowns had occurred at Fukushima, one must look at all official data with a healthy degree of skepticism.
9
There are highly radioactive naturally occurring radionuclides, such as radon and its daughter product, polonium, which have very short half-lives. These are not commonly found in foodstuffs because they self-destruct long before they can make it into the food chains.
10
The 88 curies per gram includes the decay process of cesium-137 to barium-137m, in which the barium-137m emits high-powered gamma radiation. Barium-137m has a half-life of not quite three minutes.
11
The models use weighting factors to multiply the estimated biological effects of various atomic particles (twenty times for alpha particles) and the given tissue where it resides. But the multiplication is quickly negated by many orders of magnitude when the dose given to a tiny cluster of cells is averaged over the organ system or body area in which the tiny cluster of cells resides.
12
R. Alvarez, J. Beyea, K. Janberg, J. Kang, E. Lyman, A. Macfarlane, G. Thompson, and F. von Hippel, “Reducing the Hazards from Stored Spent Power-Reactor Fuel in the United States,”
13
“The Big Picture,” RT.com, May 17, 2011, retrieved from http://www.youtube.com/watch?v=xEFtfkJc4kM.
14
These scientists declined my request to republish the image here, but it can be found online as slide number 25 in Gayle Sugiyama and John Nasstrom, “Overview of the NARAC Modeling During the Response to the Fukushima Dai-ichi Power Plant Emergency,” International Workshop on Source Term Estimation Methods for Estimating the Atmospheric Radiation Release from the Fukushima Daiichi Nuclear Power Plant, February 22–24, 2012, http://www.ral.ucar.edu/nsap/events/fukushima/documents/Session1_Briefing3-Sugiyama.pdf.