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This diary is the latest in an ongoing series that aims to provide information on the impacts of the Fukushima disaster on the health of the marine ecosystem and the public on the west coast of North America.  The purpose of this diary is to address the relative releases of radioactive cesium (137-Cs) and plutonium isotopes to the environment from Fukushima. Both elements can cause short and long-term health problems. Plutonium is an alpha-emitting isotope that carries significant radiological health risks if internalized so understanding the amount released is key. Online and in some media there exists a misconception that "massive" amounts of Pu escaped from the reactors. Modeling studies and existing measurements demonstrate that the total activities of Pu isotopes released from Fukushima were 1 to 10 million times lower than the activity of 137-Cs reflecting Cs's much higher volatility. While there was ~3.5 times more Pu isotopes in the Fukushima reactors versus the Chernobyl reactor at the time of the respective disasters the percentage of core inventories released from Fukushima were about 100,000 times lower.  Where possible I have linked to open-access scientific studies but some primary references, despite best efforts, are behind pay walls. More below the fold.  

Those unfamiliar with the units scientists use to discuss radioactivity should consult a previous diary where a brief review is presented.

Model of Pu Release from Fukushima
In a study published in the peer-reviewed journal Environmental Science and Technology in 2012 Schwantes and co-workers (behind a pay wall unfortunately) considered radionuclide measurements made in the vicinity of the reactor sites to determine the extent of release of fission products and fuel.  The study determined that the release of elements to the atmosphere was primarily controlled by how volatile and how easy it was to chemically reduce the oxide form of a radioisotope.  The lower the boiling point of a radioisotope and the more easily its oxide could be reduced in the primary containment vessel at the site the more volatile was the element leading to more total release to the environment.  Based on analyses of the fission product 137-Cs and the Plutonium isotopes 238, 239 and 240 Schwantes and colleagues determined that roughly 0.002 - 0.004% of the inventory of Pu of reactors 1 and 3 at the site were released to the environment.  This study makes important predictions about the relative activities (Bq) of 137-Cs and Pu isotopes (Pu release about 1-10 million times less than 137-Cs) in the environment that can be tested by making measurements of air, soil and seawater.  It is important to point out that this article did not consider the direct mobilization of elements to the ocean and that we will consider measurements of Pu in the ocean below.

Cesium and Plutonium Measured in the Air
The radioactive plume of elements released to the atmosphere from Fukushima was detected globally in the days following disaster and measurements of the activities of these elements in air were made.  For example, The atmospheric signal from Fukushima was first detected over Europe on March 19 by a Comprehensive Test Ban Treaty Organization monitoring station in Reykjavik, Iceland.  Maximum activities of 137-Cs of 0.05-1 milliBq/m3 air were measured over Europe which were 1,000 - 10,000 times lower than 137-Cs activities measured in the weeks following the Chernobyl disaster in 1986 (Povinec and others 2013).  Pu from Fukushima was detected in air as well with activities of 239,240-Pu of ~45 nanoBq/m3 which is about 10,000 times lower than the activities detected over Europe resulting from the Chernobyl disaster. The relative activities of 137-Cs and Pu isotopes in the atmosphere are consistent with Pu release about 1 million times less than that of 137-Cs.

Cesium and Plutonium Measured in Soil in Japan
In an open-access, peer-review study Zheng and co-workers report on 137-Cs and Pu isotope activities in soils northwest and south within 20-30 km of the Fukushima reactor sites (see map).

Map showing soil sampling sites for Zheng et al. (2012)
Activity ratios of 137-Cs to the Pu isotopes were found to be 200,000 to 25,000,000 with 10-1,000 times less Pu relative to Cs released from the Chernobyl accident.  A comparison Pu releases from Fukushima and Chernobyl disasters is presented in the following table from Zheng and others:
Comparison of Pu releases from Fukushima and Chernobyl nuclear disasters
The estimates of Pu releases from analyses of soils in Japan suggest that while there was >3.5 times the Pu present in the Fukushima reactors compared to Chernobyl at the time of the disaster about 100,000 times less was released from Fukushima to the environment. About 0.00002% of the core inventory of Pu was released from Fukushima according to their analyses.

Plutonium Released Directly to the Ocean
Less in known about the extent to which Pu was released to the marine environment.  Measurements of coastal marine sediments and estuaries in Japan in 2011 and 2012 were carried out and reported by Bu and colleagues in the open-access, peer-reviewed journal Biogeosciences in 2013.  By July 2012 they were unable to detect changes in the activity or isotopic ratios in the sediments owing to Pu originating from Fukushima.  All the measurements showed that the Pu present in marine sediments reflected the presence of fallout from atmospheric weapons testing in the 20th century.  There is a great need for sensitive measurements of Pu dissolved in seawater to determine how much Pu relative to 137-Cs was released directly to seawater.  Ongoing monitoring of Pu in seawater is identified as a high priority task for the oceanographic community.

Summary
Taken together, modeling studies of the relative atmospheric releases of 137-Cs and Pu and measurements of the isotopes in air, soil and the marine environment suggest that a trace amount (0.002 to 0.00002%) of Pu from the core inventories at Fukushima were released to the environment.  Release of Pu from Fukushima was about 100,000 times lower than the Pu release from Chernobyl in 1986 and 5,000,000 times lower than the Pu released from atmospheric weapons testing in the 20th century (Table 9).

Going forward more monitoring will needed to determine the distribution of this important alpha-emitter in the environment given the potential for significant radiological health risks.  Given ongoing release from the disaster site monitoring of the activity and isotopic composition of Pu in the marine environment and its organisms will be a key component of determining the fate of Fukushima derived Pu.

Originally posted to MarineChemist on Sun Mar 30, 2014 at 12:07 PM PDT.

Also republished by SciTech.

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Comment Preferences

  •  wherever the core is . . . (13+ / 0-)

    there the Plutonium is.  Best not to go there.

    Now, where's that pesky core ? ? ?

    What made Chernobyl so bad (apart from scarcely any attempt at containment in the reactor design) was the aerosolizing of the fissile core material by the graphite fire.  Chernobyl burned up where Fukushima melted down . . . and that has made a substantial difference.

    Fake Left, Drive Right . . . not my idea of a Democrat . . .

    by Deward Hastings on Sun Mar 30, 2014 at 12:29:31 PM PDT

  •  Greatly appreciate your posts on this matter, (14+ / 0-)

    and I hope you will find it worthwhile to continue.  Your displaying of comparative numerical data is particularly helpful.  Thanks for that.

  •  Health Physics (4+ / 0-)
    Recommended by:
    T100R, doc2, wonmug, MarineChemist

    Your calm and factual post provides an effective antidote to generalized fear and media sensationalism.

    Radon gas is a far more serious threat, no?

  •  Thanks for these updates (1+ / 0-)
    Recommended by:
    MarineChemist


    I am affiliated with the Union of Concerned Scientists, and one of their leading scientists has just recently produced a book on Fukushima, and I hope to get a copy soon.

    "Kossacks are held to a higher standard. Like Hebrew National hot dogs." - blueaardvark

    by louisev on Sun Mar 30, 2014 at 04:49:00 PM PDT

  •  Numbers are handy. Thanks. (2+ / 0-)



    Is it true? Is it kind? Is it necessary? . . . and respect the dignity of every human being.

    by Wee Mama on Sun Mar 30, 2014 at 05:55:23 PM PDT

  •  this is the problem though (0+ / 0-)
    While there was ~3.5 times more Pu isotopes in the Fukushima reactors versus the Chernobyl reactor at the time of the respective disasters the percentage of core inventories released from Fukushima were about 100,000 times lower.
    now why would the release be almost a million times less
    then chernobyl?

    to a first order, the releases at Fukushima should be 4X to 10X the release at Chernobyl.

    You had 4 reactors in meltdown and you had compromised
    fuel storage pools.

    •  Hi patbahn (0+ / 0-)

      There were 3 meltdowns.  There wasn't fuel in the #4 reactor.  

      The release of metals in an accident is a function of how volatile is the metal and the reduction/oxidation potential required to reduce the metal to a more mobile form.  The conditions under which the Chernobyl site burned in the open atmosphere volatilized and therefore released substantially more Pu than did the meltdowns at Fukushima.

      This is predicted by the calculations of Schwantes and others and borne out by measurements of Pu and its isotopic composition in air, water and soil.  If you read the report of Schwantes it is well explained there.

      All available evidence supports orders of magnitude lower release of Pu to the environment from Fukushima when compared to the Chernobyl disaster.

      •  i can see Pu not volatilizing (0+ / 0-)

        but the Cs shoul be huge

        •  Cesium and Iodine (0+ / 0-)

          The release of radioactive cesium was huge, yes but a lot of it never made it out of the reactor vessels, the containments and the buildings and it's still in there being actively cooled so it doesn't volitalise and escape further. The initial severe problem was the escape of radioactive iodine, I-131 which is also volatile and which has specific problems with uptake into the thyroid. In that case the same situation applied that a lot of the iodine was retained by the reactor structures and eventually decayed in place.

           A back-of-the-envelope estimate is that there was about 100kg of Cs-134 and Cs-137 in the three reactors at the time of the tsunami. Various estimates using monitoring, programs like SPEEDI and frankly some guesswork says that less than 5kg of the reactor core load of Cs-137 escaped into the wild, probably the same for Cs-134.

           In the case of the Chernobyl release the core burned white-hot while exposed directly to the atmosphere for several days hence nearly all of the volatile fission products in the reactor such as cesium and iodine were dispersed widely. Most analyses say the Chernobyl release was five to ten times worse than the Fukushima incident in terms of amounts of radioactive material dispersed even though three reactors were involved in the Japanese incident.

          •  containment was broken. (0+ / 0-)

            you start with a really fault assumption.

            Racs 1-3 melted out of their containments,
            it's all water transport.

            Now,  is the CS and SR running in the water cycle
            i could see that.

          •  given the japanese were hiding SPEEDI (0+ / 0-)

            data and lying about source terms,
            i'd be very dubious about your assumptions.

            I'd like to see how you got to 100 KG of CS-137

            •  Hi patbahn (0+ / 0-)

              It is easy to relate activity to mass of a radioactive element.  137-Cs has about 3 TeraBq (10^12 Bq) per gram.  If you have tens to hundreds of PetaBq 137-Cs released as the models and measurements support then you divide those two numbers and divide by 1000 to change units to kg.  For an estimated 100 PBq 137-Cs release, for example, you calculate 3.3x10^4 grams or 33 kg 137-Cs released to the environment.

              You can see the formula that relates activity to mass and half-life here.

              •  but you are starting at 100 PBq release. (0+ / 0-)

                I'm not sure that's a good number.

                I'd start at somewhere between 1700 PBq and 17,000 PBq

                •  Hi patbahn (0+ / 0-)

                  I base my starting point on measurements and evidence.  There is absolutely no evidence that would support the figures you quote.

                  References where you can find estimates of 137-Cs release from Fukushima:

                  Povinec et al. (2013)

                  ~80 PBq

                  Buesseler (2014)

                  4-90 PBq

                  Both papers have references within that point to the original work on which the estimates are based.  Why would you start at 1,700-17,000 PBq?  Do you have any references to support such a statement?  

                  The entire 137-Cs inventories of the reactor cores 1, 2 and 3 at the plant at the time of the accident were about 700 PBq so releasing 17,000 PBq would violate mass conservation.  Including all the 137-Cs in the spent fuel pools in 1, 2, 3 and 4 comes to 2,590 PBq 137-Cs.  All of this information comes from the following book published byPovinec, Hirose and Aoyama Fukushima Accident: Radioactivity Impact on the Environment. If you are interested in this topic I highly recommend buying the book or checking it out from your local library.  It is a great resource.

                  There are no measurements that support your numbers; that 100% of the 137-Cs inventory was released as a result of the Fukushima disaster.  Only 13% of the 137-Cs inventory was released from Chernobyl for example.

                  If you have references to back up any of your statements please provide them.  If they are only what you believe to be true then they have no place in an evidence based discussion.  

                  •  Total release (0+ / 0-)

                    The Journal of Nuclear Science and Technology carried a paper in March 2013 which calculated release figures of 13 PBq (1 PBq = 10^15Bq) of Cs-137 from the incident based on Cs-134 sampling. They also calculated the release of I-131 to be 200 PBq, over ten times as much activity (although a much smaller quantity of more active material). Rod Adams, a nuclear engineer calculated that the two amounts, if those figures are correct, add up to about 4kg of Cs-137 and 43 grammes of I-131 were released.

                     I've seen some commentators mention the total release of radioactive material and ascribe all of it to a single isotope which is the focus of their concerns. Sr-90, Cs-134 and Cs-137 are important isotopes because of their half-life but they represent only a fraction of the total amount of radioactivity released in the Fukushima incident. Saying that much of the radioactive material released such as I-131 has now decayed into stable elements and no longer poses any kind of radiological threat.

                  •  The Japanese have had big reasons to lie (0+ / 0-)

                    about the release characteristics and to censor the
                    science data. Much as the Soviets did.

                    So, the scientific record isn't going to be as robust as
                    we would like.

                    http://in.reuters.com/...

                    Tepco, set to be nationalised in July in exchange for a Japanese government bailout, estimated meltdowns at three Fukushima reactors released about 900,000 terabecquerels of radioactive substances into the air during March.

                    That was 2-1/2 times the amount of the first estimate by Japan's Nuclear and Industrial Safety Agency in April last year and about 17 percent more than the highest estimate provided by the government safety agency.

                    Granted that's probably referring mostly to I-131, but, to a rough order, that's a good start.
                    •  Hi patbahn (0+ / 0-)

                      The international scientific community is measuring the amount of activity that was released.  It has little to do with what the Japanese government or TEPCO says or does not.

                      It certainly doesn't change how divorced from reality suggesting 17,000 PBq 137-Cs release sounds.

                      •  How many scientists is japan letting in? (0+ / 0-)

                        Are you over there, sampling?

                        In general there are far too many entities with profits
                        based upon lying and covering up things.

                        There are far too few disinterested parties.

                      •  science has trouble with pathological liars (0+ / 0-)

                        all the science in the world isn't going anywhere
                        with the climate change deniers.

                        It's going to be hard doing real research with the
                        pathological liars that are at Tepco and the JPG.

                        if you were starting from scratch and
                        had a reasonable budget, what kind of
                        sampling program and survey program would you want to run?

                        •  Hi patbahn (1+ / 0-)
                          Recommended by:
                          nojay

                          I spend a considerable amount of time providing climate change deniers with measurements and scientific consensus to which they seem immune.  I see strong parallels between climate deniers and your response to measurements and scientific consensus here and in your comments to other diaries I have written.

                          Like I respond to climate change deniers when they question the science behind climate change I invite you to supply peer reviewed studies to support your position.

                          •  There isn't a lot in the scientific record (0+ / 0-)

                            but,  there is also a lot to indicate the JPG
                            has been actively blocking research.

                            That makes it very hard to figure out what went on.

                            I understand why they are doing that.
                            They have some 48 reactors worth half a trillion
                            and which were producing the lion's share of electricity
                            in their home islands.  Since the quake, Japan has been
                            running a trade deficit as they operate antiquated
                            coal and oil fired plants and reduce industrial operations.

                            That means you have a very powerful player that doesn't want any more political agitation on nuclear operations
                            then they already have.  

                            Given the cost of cleanup they also have tremendous incentive to downplay the scope.  

                            The dynamics of this accident may be very different from
                            chernobyl, with the cores melted and down in the ground
                            with ground water moving the isotopes around.

                            I'll take the sampling done by outsiders at face value,
                            but i'll remain extremely skeptical about the source term
                            because a full survey by outsiders hasn't been done.

                          •  Hi patbahn (0+ / 0-)

                            Qualitative arguments like

                            there is also a lot to indicate the JPG
                            has been actively blocking research
                            are not useful.  Perhaps the reason that
                            There isn't a lot in the scientific record
                            to support what you think or believe to be happening is that your belief might not be correct.  
                          •  there are many scientific problems made intractabl (0+ / 0-)

                            due to politics.

                            Iraqi casualties since 1991.

                            climate change,

                            fukushima.

                  •  the buessler article is misrepresenting data (0+ / 0-)

                    i'd hate to accuse Buessler of lying but,
                    i'd think someone as smart as he is would
                    want a much more honest graphic.

                    That one about Radioactive deposition in the
                    oceans...

                    It's blending Fukushima which is a pacific event
                    with K-40 which is a global event.

                    Plus the biosphere is very keyed to Pottasium
                    decay products,  CS-137, is something the system hasn't
                    had a lot of

                    •  Hi patbahn (0+ / 0-)

                      The graph is labeled as it should be and accurately reports the relative oceanic inventories of the radionuclides.  You are correct to say that most of the radionuclides released from Fukushima ended up in the Pacific.  The activity per litre or cubic meter of seawater for 137-Cs resulting from Fukushima will likely not be as high as it was post weapons testing fallout in the 60's and 70's.

                      Read here

                      •  i still think the source term is what matters (0+ / 0-)

                        and you start with the maximum source term and then
                        work down, not what the japanese tell you and work down
                        from there.

                        •  Hi patbahn (1+ / 0-)
                          Recommended by:
                          nojay

                          I am not sure how many times this must be repeated.  What I report on above and in all my diaries has nothing to do with "what the japanese tell me".  

                          These are published, peer-reviewed studies.

                          •  The sampling done (0+ / 0-)

                            is only what they let you do.

                            so it's at best sampling at long distance

                            from there you are trying to work back and
                            estimate a source term.

                            We know the maximum source term is a complete release
                            of the core loads and the SFPs, that bounds the upper level.

                            now what the release dynamics are, is a different question,
                            but i'd never trust a source term, without really serious
                            drilling into the site.

                      •  the graphic on page 94 of buessler (0+ / 0-)

                        http://www.tos.org/...

                        seems misleading.

                        The figure for 15 Million PBq for K-40, appears to be the
                        amount for all the oceans,  it should be scaled to the North
                        pacific.

                        Then K-40 is chemically and energetically different from
                        CS-134,137, etc,,  The biosphere is pretty tuned to what
                        is in the ocean, and the crust,  but add in a lot of short lived
                        isotopes.

                        K-40 has a billion year half life, while CS-134 has a 2 year
                        and CS-137 has a 30 year half life.  Those are going to be
                        much more active and have very different biological activities.

                        As for Global nuclear weapons testing, that's probably a lot better baseline comparison, but, that was a series of events spread out over time.  You can slice the numbers how you want, but,at a minimum this is an event like any one year of Nuclear weapons testing all the way up to this was an event much worse then all nuclear weapons testing.

                        •  Hi patbahn (1+ / 0-)
                          Recommended by:
                          nojay
                          As for Global nuclear weapons testing, that's probably a lot better baseline comparison, but, that was a series of events spread out over time.  You can slice the numbers how you want, but,at a minimum this is an event like any one year of Nuclear weapons testing all the way up to this was an event much worse then all nuclear weapons testing.
                          You really need to familiarize yourself with the numbers rather than speculating.  The numbers exist to test your statements. It is not factually correct.

                          Please read the following report from UNSCEAR that summarizes radionuclides released to the environment from weapons testing.

                          In Figure 5 and 6 the release of 90-Sr to the atmosphere is summarized. In every single year from 1950-1980 (30 years) the amount of 90-Sr released to the atmosphere in the Northern Hemisphere alone was equal to or greater than the total release from Fukushima.

                          For 137-Cs you can consult Table 10. Every year from about 1954 to the mid-1960's ~10-90 PBq were released due to testing which, given the range of estimates for Fukushima release, is roughly a Fukushima every year for about a decade.

                          •  which brings us back to source term (0+ / 0-)

                            if a 750 MW reactor, a 1 GW Reactor, a 1 GW reactor and
                            a 1.2 GW reactor meltdown or suffer serious damage. ,  how much cesium would you expect to be involved?

                          •  Hi patbahn (1+ / 0-)
                            Recommended by:
                            nojay

                            The source term based on all available measurements of seawater, air and soil is between <100 PBq.  You can consult all of the studies I have linked to above.  What I expect matters about as much as what you expect.  It matters very little in the face of modeled estimates that are supported by evidence collected in the environment.

                            Again, saying you simply disbelieve the measurements of the international science community is insufficient.  If you aren't interested in fact based discussions of the issue then why read and comment on a diary devoted to an accounting of evidence?

                            Regards.

                          •  try an engineering based analysis. (0+ / 0-)

                            If there are 175 tons of fuel in a reactor and it melts
                            down, how much radio-active material do you
                            expect to be released?

                            Now, if your samples show it's not in one stream in the pacific, then you should look to see where it is.

                            It's kind of like searching for oil from the DeepWater horizon.
                            If it's not on the surface or on the beach, then where is it?

                            And that's a useful question for a marine chemist.

                          •  Hi patbahn (0+ / 0-)

                            For an engineering and physical chemistry based analysis please see Schwantes et al here. This diary compares their analysis of the situation with measurements in the environment that largely support their conclusions.

                            Rather than write anything else I'll thank you for your tips.  It is good to know that the permalink to this diary and your comments will be here in case I need to look them up in the future.

                            Regards

                          •  There is an error in schwante (0+ / 0-)
                            The reactor at Unit 4 had been shut down since November 30, 2010, and all of its fuel had been offloaded to the shared spent fuel pool nearby. 
                            Schwante is probably right the shared SFP is one of the
                            largest common pools, but,

                            there are lots of press reports that Tepco is
                            emptying the spent fuel pool at Reactor 4 (1F4).

                            such as

                            http://enformable.com/...

                            On Monday at 15:18, TEPCO workers began work removing spent fuel from the crippled Fukushima Daiichi Unit 4 spent fuel pool, which holds 1,533 assemblies.  Of the 1,533 assemblies, 1,311 are spent fuel, the other 222 are unused.
                            or

                            perhaps if you don't trust enformable, let's ask WINO
                            (World Industry d'Nuclear Organization)...

                            http://www.worldnuclearreport.org/...

                            At the time of the earthquake and tsunamiUnit-4 was not operational and was undergoing a periodic inspection. All fuel had been taken out of the reactor vessel and moved to the spent fuel pool, where older spent fuel assemblies were also stored. At approximately 6:10 am, 15 March 2011, the Unit-4 building exploded, blowing the upper-floor walls and the ceilings away, leaving the spent fuel pool filled with 1,535 assemblies (1,331 irradiated ones and 204 fresh ones) [279] in the open air without containment, though debris fell into the pond.
                            When  A Guy like me finds an obvious error like that by a guy like Schwante, it worries me to no end that far more subtle errors are in there.

                            Jay, I work in aerospace, i often times see awesome, detailed scientific models, that aren't as useful a guide
                            as sitting there with a white board and some markers.

                            I'll see great CFD models, and i'll just spitball a L/D ratio, estimate a cross range, and decide wether the mission is practical. The complexity of an analysis oftentimes hides the flaws of key assumptions, while the spitball analysis shows them.

                          •  Hi patbahn (0+ / 0-)

                            Shutdown meant that the reactor itself was in the SFP not that the facility was empty.

                            Regards

                          •  the quote i made was poorly formatted (0+ / 0-)

                            it should read

                            2010, and all of its fuel had been offloaded to the shared spent fuel pool nearby. 

                            The reactor at Unit 4 had been shut down since November 30, 2010, and all of its fuel had been offloaded to the shared spent fuel pool nearby.
                            I read schwante as saying the fuel had gone to the SFP-4
                            now, in other places he talks about the unit 4 pool,
                            but it seems like an error.
                          •  schwante uses Tepco and models (0+ / 0-)
                            Analytical results of environmental surveys taken from across the Fukushima Daiichi facility grounds and 
                            published on the TEPCO website within the first 20 days after the earthquake are provided in Tables 1 
                            through 3. Table 4 provides model output from ORIGEN ARP computations designed to replicate the 
                            average radionuclide inventories within Units 1 and 3 just before venting and that of the most recently 
                            off‐loaded fuel stored in the spent‐fuel cooling pool at Unit #4. 
                            brings us back to the source term argument.

                            I'm sure Schwante knows how to run Origen, but
                            he's going to depend hard upon source term and if TEPCO
                            gives him bad data, then it's bad data

                          •  here's a modeling paper by alava and gobas (0+ / 0-)

                            http://enenews.com/...

                            Modeling the Bioaccumulation Potential of Cesium 137 in a Marine Food Web of the Northwest Pacific, Canada

                            Juan Jose Alava, Frank A.P.C. Gobas
                            11/2011; In proceeding of: Society for Environmental Toxciology and Chemistry (SETAC) North America 32nd Annual Meeting, Volume: Abstract Book, 2011, Society of Environmental Toxicology and Chemistry North America 32nd Annual Meeting
                            ABSTRACT The Fukushima nuclear emergency provoked by the tsunami that impacted the north east coast of Japan on March 11, 2011, emerged as a high priority looming threat due to the risk of radioactive contamination in the global ocean and biodiversity. On April 11, The Fukushima nuclear plant reached the severity level 7, the same as the 1986 Chernobyl nuclear disaster. One of the most persistent isotopes produced and expected to be released by this kind of nuclear accidents was Cesium 137 (137 Cs), with a physical half life of 30 years. In an effort to assess the fate, accumulation and health effects of 137 Cs in marine organisms of the Northwest Pacific after the Fukushima nuclear disaster, we assessed the bioaccumulation potential of 137 Cs by testing steady state and time-dependent bioaccumulation models in an offshore food web that included fish-eating, resident killer whales (Orcinus orca) as one of the major top predators of the marine ecosystems in British Columbia, Canada. The steady stated model showed that concentrations of 137 Cs predicted in the male killer whale were approximately three orders of magnitude higher relative to its major prey, Chinook salmon, and > 13,000 times higher compared to phytoplankton. The time-dependent model showed that after 30 days of radioactive spillage, the 137 Cs concentrations accumulate gradually over time in high trophic level organisms (salmon and killer whales), which exhibited low concentrations likely driven by slow intake rates, while it bioaccumulates at faster uptake rates in low trophic level, gill ventilating organisms (phytoplankton, zooplankton, benthic invertebrates and planktivorous fish), exhibiting concentration about one to two orders of magnitude greater than that in killer whales. At 9125 days (25 years), the predicted concentrations of 137 Cs accumulate in a higher degree in killer whales, being >2 orders of magnitude greater than that predicted in Chinook salmon and 10,000 times higher relative to phytoplankton. The levels of 137 Cs predicted in biota (shellfish and fish) exceeded well above the 137 Cs action level for commercial food/beverage of 1000 Bq/kg established by the Canadian Guidelines for Consumption following a Nuclear Emergency.

                            what do you think?
                          •  Hi patbahn (0+ / 0-)

                            Will be interesting to read when and if it gets through the peer-review process.  This is a conference abstract and not a paper as Energy News states.  They get a lot of facts wrong.

                            It is hard to evaluate what sort of assumptions have been made to arrive at the figures they report above.  My initial reaction is that the numbers seem high given concentrations in the environment.

                            According to these figures the older orca should still have high 137-Cs activities that would be easily measurable owing to weapons testing.  It could be tested.

                          •  conference papers are the first rung (0+ / 0-)

                            lots of interesting stuff at conferences.

                            it is a generational paper. looking at
                            absorption rates for 30 years.

                            Of course, I tend to be a little skeptical of all modeling
                            papers.

                            Now if you poke around that conference, there are
                            some interesting papers about submarine hydrology
                            in the tohuko area.

                            It could be the corium is stuck down below the reactors,
                            and somewhat contained by that. It may take a while for
                            the water cycle to kick it off shore.

                          •  not to be a jerk but, (0+ / 0-)
                            Results 
                            Analytical results of environmental surveys taken from across the Fukushima Daiichi facility grounds and 
                            published on the TEPCO website within the first 20 days after the earthquake are provided in Tables 1 
                            through 3. Table 4 provides model output from ORIGEN ARP computations designed to replicate the 
                            average radionuclide inventories within Units 1 and 3 just before venting and that of the most recently 
                            off‐loaded fuel stored in the spent‐fuel cooling pool at Unit #4.
                            schwante starts with TEPCO's data then feeds it into a model.

                            This is again depending upon the japanese and looking to Tepco for a source term.

                            Tepco is a bunch of patholigical liars  and you can't use their data at all, except to establish a floor. Where is the ceiling?
                            somewhere less then 100% evolution of the fuel loads.

            •  Fissile products in spent fuel (0+ / 0-)

              Working out how much of a particular fission product is present in spent fuel is complicated but there are some basic starting points. One of them is the M-curve of fission yields which you can see here. Because nuclei fission assymetrically more of some isotopes are produced than others. Cs-134 and Cs-137 are quite common at about 6% each i.e. one in eight fission events results in one of these two isotopes. They also have significant half-lifes, more than a typical refuelling cycle so they are present in large quantities in spent fuel. A lot of the other fission products have short half-lifes, some lasting only seconds, some like I-131 a few days and since the fuel usually spends over a year in the reactor before it is replaced what's left of the short half-life isotopes at shutdown is not a high proportion compared to the Cs-134 and Cs-137 residues. Sr-90 is another common longer-lived fission isotope on the other side side of the M-curve.

               Spent fuel is more than 90% U-238, the non-fissile isotope of uranium that predominates in the raw metal. There's maybe 2% U-235, the fissile isotope that provides most of the enrgy the reactor produces during operation. The fuel started off at about 5% enrichment, natural uranium is about 0.7% U-235 for comparison.

               A couple of percent of the fuel will now be Pu-239 and Pu-240, produced by breeding U-238 by neutron capture. Some of that Pu will have been fissioned after it was produced during operation but when the reactor is shut down there will still be some left.

               The rest is "waste", fission isotopes which can't be recycled into new fuel rods. Some of these isotopes damp down the fission reaction, so-called "fission poisons" and they tend to set the limit when the fuel needs to be swapped out. That waste makes up maybe 3% of the mass of the spent fuel.

               Reactor 1 at Fukushima had a bit less than 100 tonnes of fuel loaded at the time of the tsunami. Reactor 2 and 3 were larger and each had more fuel but in round numbers there was about 300 tonnes of fuel involved in the meltdowns. 3% waste means there was about 10 tonnes of "waste" fission isotopes in the reactors, much of which is very short-lived and decayed to nothing a few days after the accident while releasing most of the heat that caused the damage.

               What I don't know and couldn't find out about the Fukushima reactors in operation at the time of the accident was how long they had been running -- the longer they were in operation the larger the inventory of isotopes like Cs-134 and Cs-137. If they had only been running for a month or two since their last outage then the quantities would be much less than when the fuel was ready for replacement. A figure of about 100kg total of Cs-134 and Cs-137 sounds about right to me, it could be higher. It can't be more than a tonne as the physics of the operation don't allow for it as far as I can see.

  •  The Asia-Pacific Journal (0+ / 0-)

    The Asia-Pacific Journal,Vol.12,Issue 7,No.4,February 17,2014
    Extract A:
    ‘…Through out this time the reactors continuously plumed out radiation into the environment.When seen through the refracted gaze of the media, it seemed as though the radioactive plumes that escaped the Daiichi plant were severe, but episodic and limited. In fact, the plumes that made their way into the atmosphere after the venting and hydrogen explosions were peak Releases, but they were merely steps above an already elevated level that fluctuated but never stopped.
    One way to visualize this is to imagine the plume as a spotlight that swept back and forth, continuously pluming out radioactivity in the direction that light was shone: as the wind shifted the plume would move, but it never stopped. The plume was unrelenting (and, arguably, still is today in another mode, as contaminated water leaks into the ocean), and as this radioactivity has been released into the environment, it has incrementally distributed collective, cumulative doses whose consequences for public health were terrifying in the early days of the crisis but may well be even worse in the long-term….’

    •  Hi Rob Hound (0+ / 0-)

      This article is published in an online sociology journal and the author Kyle Cleveland is a sociologist whose expertise

      ranges from political and theoretical sociology to race and ethnicity, popular culture and ideology
      The qualitative statements you quote from the article add little to this discussion.

      The release of radionuclides from the Fukushima site is ongoing but best measurements put the rate of release at 10,000-100,000 lower than in the few weeks following the disaster. What this means is that in order to match the amount 137-Cs released in the first 90 days after the disaster it will take about 5 million days at current release rates.

      If you have a genuine interest in the impacts of the disaster I urge you to consult this open-access, peer-reviewed scientific journal Biogeosciences which maintains a special issue on Fukushima here.

      While sociologists like Cleveland have much to contribute by examining the response of society and government to the disaster I think that their analysis and assessment of the impact radionuclides on the environment and estimates of radiological health risks to the public might have limited value.

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