In last week’s op-ed piece (November 2), the chemical and biological hazard of Cesium, isotope 137 (Cs-137) was summarized. This week, we will look at how Cs-137 has been used to speculate on risk relative to the spent fuel pools at Fukushima Daiichi.

Cs-137 is a by-product of the fission process that occurs inside nuclear power plant fuel cores. There are actually 47 radioactive elements formed when the Uranium-235 in the fuel is fissioned, and literally hundreds of isotopes of those elements. A nuclear weapon’s detonation also produces the same types of radioactive isotopes, plus hundreds of others not found in reactors. This is because of the intense, concentrated, high energy neutron field inherent to the detonation itself. Reactor fission products range from Zinc to Dysprosium on the Periodic Chart of the Elements. On the other hand, the bomb’s isotopic matrix is much, much wider with as many as 71 elements (and many hundreds of their isotopes), from Sodium and Lead on the Periodic Table. Not all of the bomb fallout isotopes come from fission. Neutrons are the only form of radiation that can make other surrounding materials radioactive. The soils, buildings, and other materials pulverized by a bomb’s explosion are instantly caught in the neutron field caused by the detonation, making radioactive isotopes out of those that were not radioactive before the blast. Some of the prominent bomb-fallout isotopes are Sodium-24, Chromium-51, Manganese-54, Iron-59, Cobalt-60, Copper-64, Antimony-122 and 124, Tantalum-180 and 182, and Lead-203.(1) The half-lives vary from as low as 8 hours (Ta-180) and as long as 5.3 years (Co-60). Just for the record, a small amount of Carbon-14 is formed by the bomb, but its quantity is miniscule compared to those just listed. Regardless, none of the bomb-fallout isotopes listed above is produced by power plant reactors.

Both reactors and bombs produce the popularly-mentioned isotopes Iodine-131, Cs-137, and Strontium-90. I-131 has a half-life of 8.1 days, Cs-137 at 30.1 years, and Sr-90 at 29 years. The length of an isotopes half-life indicates how long it will last, in ever-descending activity level, if we multiply by ten. While the amount of Cs-137 spawned by a bomb is relatively minute, the amount made in a reactor over a period of years is much greater. The documented fatalities caused by bomb fallout were due to the entire spectrum of isotopes produced, but to say that they all died by Cs-137 exposure is a gross exaggeration.

Case in point – the Daigo Fukurayu Maru in 1954. The Maru was a Japanese fishing ship located about 130 kilometers downwind from America’s largest-ever atmospheric nuclear weapon’s test, code-named Bravo, rated at 15 million tons of TNT – roughly 1,000 times more powerful than the bomb dropped on Hiroshima. The 40,000 ft.-high cloud was visible to the Maru and the sound of the blast quite loud. The Maru pulled in their fishing equipment and tried to sail away. Unfortunately, they sailed into the path of the bomb fallout. Dust, soot and even larger particles rained down on the Maru and her 23-man crew. The crew received high internal and external radiation exposure, estimated at 3 sieverts each. All experienced nausea and those on deck received superficial skin burns from the Beta particles pouring out of the fallout around them. One crew member died some six months later due to acute hepatitis. All others recovered from their symptoms. Seventeen remain alive today. Regardless, the crew’s radiation exposure was due to the entire range of radioactive isotopes they were subjected to. No reputable research attributes the crew’s illnesses to Cs-137 alone (2,3)

Let’s also look at the data relative to fallout from the bombings of Hiroshima and Nagasaki in 1945. It is estimated that some 201,000 people died as a result of Hiroshima/Nagasaki; 130,000 killed by the two explosions themselves, 70,000 due to radiation exposures caused by the enormous, rapid neutron and gamma exposures radiated by the two bursts, and about 1,000 due to latent effects resulting from internal and external fallout exposure by 1951.(4.5.6) The fallout-caused deaths are believed to have been the result of contact with and ingestion of the full spectrum of fallout isotopes, only a tiny fraction of which was Cs-137. In other words, those who succumbed to Hiroshima/Nagasaki fallout exposure did not die of Cs-137 exposure alone: in fact, the tiny fraction of Cs-137 in the fallout probably wouldn’t have killed anyone…the amount produced was just too small.

These unequivocal facts have not deterred hardened nuclear energy critics from making it seem as if Cs-137 was the sole culprit of all weapon’s-fallout-related and Chernobyl accident mortality. They do this to make Cs-137 exposure seem unfathomably hazardous, and use their deceptive rhetoric to predict apocalyptic consequences. At the forefront is American Arnie Gundersen, a maverick former nuclear engineer. Gundersen evokes fearful visions of Fukushima-based, nuclear-weapons-level holocaust when he says, “There’s more cesium in that [Unit 4] fuel pool than in all 800 nuclear bombs exploded above ground…But of course it would happen all at once. It would certainly destroy Japan as a functioning country. Move south of the equator if that ever happened, I think that’s probably the lesson there.”(8) It should be added that another noteworthy American, Robert Alvarez, makes a similar exaggerationwhen he compares Chernobyl and his wildly-speculative assumptions about spent fuel pool accidents. He writes that there is 85 times more Cesium in the spent fuel stored at F. Daiichi than was released by Chernobyl, therefore “It [all Cs-137 being released] would destroy the world environment and our civilization.”(7)

It would be of little consequence if doom-sayers like Gundersen and Alvarez were merely preaching to the world’s antinuclear choir, but their predictions of a Cs-137-caused apocalypse due to the spent fuel pools at Fukushima Daiichi have received wide news media coverage in Japan. And, their severely disingenuous speculations have received virtually no rebuttal in the Japanese Press. Are they “telling it like it is”, or are they successfully selling fear-inducing snake oil to millions of Japanese who have no idea what the risks of Cs-137 really are? You decide!


  1. Howard A. Hawthorne, Editor (May 1979); Operation Redwing- Project 2.63- Characterization of Fallout (extracted version); Sandia Base, Albuquerque, New Mexico; March 15, 1961.
  2. Henriksen, Thormond; Radiation and Health; University of Oslo. 2009 (updated 2012)
  3. Titus, A. Costanina; Bombs in the Backyard: Atomic Testing and American Politics; University of Nevada Press, Reno, Nevada. !986 ppg. 46-51
  4. The Atomic Bombings of Hiroshima and Nagasaki : Chapter 10 – Total Casualties; The Avalon Project; Yale Law School.
  5. Johnston, Wm. Robert; Hiroshima Atomic Bombing, 1945; Database of radiological incidents and related events – Johnston Archives; October 16, 2005.
  6. Johnston, Wm. Robert; Nagasaki Atomic Bombing, 1945; Database of radiological incidents and related events – Johnston Archives; October 16, 2005.
  7. Peterson, Per F.; Nuclear Expert: Fukushima spent fuel has 85 times more cesium than released at Chernobyl — “It would destroy the world environment and our civilization… an issue of human survival” -Former UN adviser; University of California, Berkeley; April 5, 2012.
  8. Fukushima fuel pool is urgent national security issue for America, ‘top threat facing humanity’; Kurzweil News; May 7, 2012.