Fukushima’s Radioactive Waste Elements Three Years Later: Plutonium and Cesium

Much of North East Japan Suffered catastrophic losses, including the Sendai region. Image from Nuclear Regulator Commission Report: Recommendations for Enhancing Reactor Safety in the 21st Century

Much of northeast Japan suffered catastrophic losses, including the Sendai region. Image from Nuclear Regulator Commission Report: Recommendations for Enhancing Reactor Safety in the 21st Century.

The safe disposal of chemical or radioactive waste is important – everyone agrees on that – but no one wants it in his or her backyard. Unfortunately, the amount of radioactive, harmful waste from the Great Japan Earthquake of 2011 is staggering.

While most radioactive elements have degraded, the radioactive elements that have not decayed to a measurable degree are Cesium and Plutonium, both of which can be deadly.

The Plutonium seems to have dropped from public consciousness since the early days of the 2011 earthquake. Professionals are disposing of Cesium, on the other hand, in ways that may eventually be applied elsewhere in the world.

Aspects of Plutonium at Fukushima

Plutonium, an artificial element, results from the synthesis of Uranium 238 with a neutron– it is also found as a by-product of nuclear explosions. The complete decay (or degradation) of  Plutonium 239 takes thousands of years. Estimates put the total amount of released plutonium approximately one-half of one gram.

Certain isotopes of radioactive plutonium are known as some of the deadliest poisons on the face of the earth. A mere microgram (a speck of darkness on a pinhead) of Plutonium-239, if inhaled, can cause death, and if ingested, radioactive Plutonium can be harmful, causing leukemia and other bone cancers.

In the days following the 2011 earthquake and nuclear plant explosions, seawater meant to cool the nuclear power plants instead carried radioactive elements back to the Pacific ocean. Radioactive Plutonium was one of the elements streamed back to sea. Environmental groups protested loudly.

Environmental testing of shoreline around the nuclear plant (as well fish, especially Tuna) showed negligible amounts of Plutonium in the seawater. The Plutonium, from what little is reported, sank into the sediments off the Japanese coast. Plutonium is one of the densest elements known to humankind; the plutonium that escaped after the Fukushima disaster seems to have disappeared.




Radioactive Cesium at Fukushima

Radioactive fallout of Cesium left Japan desperate for an answer to a logistic nightmare— the disposal of more than 15 years of accumulated waste generated on a single day. (Cesium, known to damage soft tissue and bone, causes bone cancer.) If left unaltered, the landscape would contribute to thousands of deaths.

The Cesium fallout resulted from the explosions that rocked four of the six nuclear reactors at the Daiichi Power Plant. Experts estimate that the total amount of waste that needs disposal or incineration is 20 million tons. The waste consists of two kinds: rural- and urban-type refuse. The refuse is further characterized by the amount of radioactive Cesium contained.

The rural waste consists primarily of radioactive soil and vegetation. Incineration of vegetation and soil generates radioactive ash, and the radioactive cesium isolated. The urban waste, once separated into sewage, garbage and ‘durable-type materials’ (concrete and steel), requires further processing. First, they burn the sewage and garbage, and then compact the durable material.

Secondly, the processed material undergoes washing to isolate radioactive Cesium. Although both compaction and incineration reduce the total volume, the mounting volume of fly ash posed a nightmarish scenario. So, the question became, how to contain the radioactive Cesium from bulk amount of ash. The answers show considerable inventiveness.

Cesium (Cs) is trapped by Prussian blue dye by removing Potassium (K) from the crystal lattice. Schematic with Chem Draw 14. Image by John A. Jaksich, all rights reserved

In a nutshell, the answer came down to understanding how the radioactive Cesium could be washed and then trapped in small batches. The smaller volume of Cesium obtained by washing in a hot acidic water bath (also known as digestion) allowed its isolation.

An organic dye (an organic molecule) known as Prussian blue selectively extracts Cesium over other elements. A solid matrix then traps the extracted Cesium in an appropriate landfill or storage.

Important research has come to the forefront as clean-up of Cesium proceeds at Sendai. Processes to remove radioactive Cesium come from findings reported from nuclear chemists in India. The process involves an oganic-cobalt molecule. The reported research, although novel and  efficient, is only in the research phase.

The Ugly Realities and the Hope in the Aftermath

Although a ‘trace’ amount of Plutonium contaminates the environment, questions remain: The degradation products may be traced; if not ingested, it may be isolated and permanently removed. The other issue is the Cesium which contaminated much of Northeast Japan.

Clean-up still goes on three-and-a-half years later. The economic burden of clean-up, estimated as $500 billion US dollars, surely will increase in cost as health issues come to the forefront. If we may glean any hope, it is that research dollars (and specific results) await in cases that may make future radioactive nightmares less likely.

© Copyright 2014 John A. Jaksich, All rights Reserved. Written For: Decoded Science

Resources for this article

Chaudhury, Sanhita, et al. Electrodriven Selective Transport of Cs Using Chlorinated Cobalt Dicarbollide in Polymer Inclusion Membrane: A Novel Approach for Cesium Removal from Simulated Nuclear Waste Solution. (2014). American Chemical Society. Accessed on November 24, 2014


Bu, Wentig , et al. Release of Pu Isotopes from the Fukushima Daiichi Nuclear Power Plant Accident to the Marine Environment Was Negligible. (2014). American Chemical Society. Accessed on November 24, 2014


Parajuli, Durga, et al. Dealing with the Aftermath of Fukushima Daiichi Nuclear Accident: Decontamination of Radioactive Cesium Enriched Ash. (2013). American Chemical Society. Accessed on November 24, 2014


Thompson, Dennis, et al. Prussian Blue for Treatment of Radiocesium Poisoning. (2001). Pharmacotherapy Publications. Accessed on November 24, 2014


NRC, et al. Recommendations for Enhancing Reactor Safety in the 21st Century. (2011). United States Nuclear Regulatory Commission. Accessed on November 24, 2014




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Comments

  1. says

    Whatever humans do by way of improving things seems to backfire at some level, doesn’t it? It reminds me of the “plan ahead” sign where the letters are squeezed in at the end of the line. Foresight and clever engineering disposal can help. For instance, some waste water (sewage) has been disposed of by using it to make concrete. Of course radioactive waste is whole n’other ballgame.

    • John Jaksich says

      Hi Vince,

      It would seem as if we need to adapt to the Earth’s ecological cycles–and to be aware of how we can make positive changes upon the Earth’s geo-chemistry. The Earth’s geochemical cycles seem to be fickle to many of us, but it learning to adapt to where and how we live might be simpler than most of us would understand. In my humble opinion, it may seem as if a paradigm shift could effect such a change but to quote many business gurus–paradigms change slowly.

  2. Bruce says

    Uranium enrichment, nuclear fission power plants for breeding plutonium, weapon proliferation, can be an eternal menace to our peace. Humanity should give a decisive farewell to nuclear fission and open their arms to aneutronic fusion that is a clean and safe source of energy to supply mankind’s future needs with no risk of radiation.

    • Snedler says

      We are open to it already..
      The reason we don’t use it for energy is because we have a lot of study to do in that area..
      I know Nasa will study it bc it’s the answer to future space exploraiton and robotics

  3. jerico says

    Seria interesante, amplificar la información sobre la peligrosidad de la radioactividad. Estamos con una mentalidad guerrera, que apunta a 2020, para una nueva III Guerra Mundial. Hay alguien lucido en los medios, para concienzar al publico y a los gobernantes, sobre los resultados de tal disparate. Gracias.

  4. Phil says

    Nothing about this had dropped from our consciousness!
    This is a nuclear disaster that may impact all Pacific sea life and the people who depend on that for jobs and food.
    I for one refuse to eat anything from the Pacific Ocean, and hopefully avoid fruits and other produce from the west coast and from Asian countries!

    That poison is cumulative!
    Just as one cigarette won’t kill you, but many will.
    You want to eat that stuff, be my guest!

  5. EKARV says

    The core of reactor 3 comprised roughly 20 tonnes (1/4 core) of newly loaded MOX fuel containing in the order of 1000 kg plutonium. A major part of this was dispersed by explosive destruction of the reactor. The explosion is likely to have been initiated by prompt (moderated ?) criticality caused through sudden addition of excessive reactivity when the core collapsed. (AREVA states that 3/4 of core lost cooling and a debris bed built up inside the reactor vessel ). The explosion, the nuclear yield of which may have exceeded 10 tonnes of TNT, ripped the reactor vessel open, blew up the reactor containment, biological shield and reactor building. The dark grey collimated plume carrying fragmented fuel and reactor materials reached hundreds of meters into she sky. The ejected materials including MOX pellets and broken fuel fell down around the reactor, some on land ( NRA states that objects had to be bulldozed over) and a large part downwind into the sea. All this can be clearly seen on video recordings. The explosion dynamics and remaining ruin of reactor 3 confirm that this was hardly just an ordinary hydrogen explosion. Fuel remaining in the lower part of the core region after the explosion subsequently overheated and melted.
    How on earth can a knowledgeable person estimate the released amont of plutonium to “a half of
    a half gram” ?

  6. Kimberly Davis says

    Why do you think the Plutonium has disappeared? Is anyone monitoring for it? Reactor 3 use MOX fuel with Plutonium and, like the other two, it exploded and the core melted. Water is streaming continuously through the site to the sea.

    Cesiurm, an “indicator pollutant”, is cheap and easy to monitor for.

    As for Strontium-90, TEPCO acknowledged last January that their monitoring methods were flawed (dilution, meter caps) and I have not seen them revised

    I am not engaging in idle speculation and fear-mongering; rather, I have systematically studied how study design and data collection has been fixed. Then of course the Japanese government made discussing nuclear accidents a federal crime (see Economist Nov. 2013); that might have something to do with it, too..

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