What isotopic ratios from the Unit 3 debris fragments tell us about the explosion there.

EX-SKF is reporting that highly radioactive debris fragments have been discovered at the river mouth in Naraha-machi, around 9 miles from the Fukushima Daiichi plant. These fragments very likely came from the explosion of Unit 3 in 2011, since the degree of contamination in them resembles that found in debris near the Unit 3 building.

Tepco has published a pdf which contains analyses of radioactive isotopes and minerals in 4 samples of this debris. These analyses can tell us a lot about what happened at the Unit 3 explosion, what the state of the corium was, where it was, if it had melted through the containment at this point.

This is very important because debris went sky-high, and likely entered the stratosphere and the jet stream, and made its way to North America. The spent fuel pool fires and other reactor meltdowns caused contamination to enter the jet stream also, but not to the degree that the Unit 3 explosion did.

The Tepco pdf indicates that the samples contain an enormous amount of radioactive cesium. They also contain antimony-125, silver-110m, cobalt-60, strontium-90, curium-244, americium-241, and various isotopes of plutonium, as well as other radionuclides. This makes it the most dangerous material found at Fukushima so far. We do know from the FOIA documents that fuel rod fragments are out there too. We will see that these samples are not from the fuel rods themselves, though.

The radionuclides found in these fragments match those found in the “black substance”, or black dust, that were found by a separate analysis. So now we have a good idea of what the source of the black substance is.

Page 42 of this pdf contains a table listing the radioisotope inventories of the Unit 3 reactor. This will tell us what the ratios between the different radioactive elements should be, for any sample of pure MOX fuel. The document also contains inventories for the Unit 3 spent fuel pool. But the two inventories are so similar that the reactor inventory will be used only. We can’t tell if the radioactive contamination came from the reactor or the pool here.

I calculated the expected ratios of radioactivity from the elements in this inventory, to amounts of cesium-137, that are listed in the Tepco document. Then I calculated the observed ratios of the averages of the 4 samples. For nuclides with short half-lives, I corrected the observed ratios to July 2013.

Radionuclide   Expected ratio   Observed ratio   Observed/Expected
------------   --------------   --------------   -----------------
Sb-125              0.04             0.0034            0.085
Ag-110m             0.002            0.0001            0.05
Co-60               0.00001          0.0002           20.0
Sr-90               0.75             0.0008            0.001
Cm-244              0.011            0.0000002         0.00002
Pu-238+Am-241       0.025            0.000001          0.00004
Pu-239+Pu-240       0.01             0.0000004         0.00004

If the samples were contaminated purely from the MOX fuel rods in Unit 3, the observed/expected ratios would all be close to 1. The first thing that strikes you is how this the ratio is for cobalt-60. Co-60 is a neutron activation product. It results from neutrons interacting with structural elements like steel. The neutrons might come from neutron-emitting radionuclides like curium and plutonium. Or they could come from a criticality. Since the ratio is 20 times higher than expected, we can safely say that the cobalt-60 resulted from a supercriticality. This is yet more evidence (if any more is needed) that Unit 3 blew up in a nuclear explosion.

Cesium and iodine are the most volatile elements from the nuclear fuel. That means they get released first with increasing heat. The other nuclides beside Co-60 all have ratios far below 1. So the debris that went into the jet stream was not the fuel rods themselves, though it was contaminated with it to some degree. If the explosion blew the MOX fuel to kingdom come, the debris would contain 25,000 times as much plutonium than was found in the fragments.

Another possibility would be that a molten corium/concrete reaction led to the nuclear explosion. Here molten corium burns through the steel containment, and interacts with the concrete of the drywell, and the floor of the building. The interaction between the molten fuel and the chemical elements and water in the concrete results in a bubbling stew, with gases escaping. This is how less volatile nuclides like strontium-90 gets released from the fuel. If the explosion occurred after this reaction was underway, a certain pattern of isotope ratios would follow.

We see from the graphic that the silver ratio would be 0.97, antimony would be 0.77, curium would be 0.003. The observed ratios are far less than this. So we can conclude that the dangerous corium/concrete reaction had not yet been underway to a significant extent.

The Tepco documents states the iron (FE) was found in the samples. The photo of the wreckage at Unit 3 indicates rust (iron oxide). This argues that melted steel was involved.

There was a nuclear explosion at Unit 3 in March 11. I believe that it was triggered by a hydrogen explosion. It occurred very early in the meltdown process, which is a fortunate thing for the northern hemisphere. The corium had melted steel, but not concrete in any significant way yet. Perhaps it happened as soon as it came into contact with the concrete.

If the explosion had happened later, it might have released 25,000 times more plutonium into the jet stream. This is not to say that it did not release a large amount of plutonium. The corium-concrete reaction probably occurred after the explosion. But it didn’t blow sky-high after this reaction, but before it.

38 thoughts on “What isotopic ratios from the Unit 3 debris fragments tell us about the explosion there.

  1. Again, thanks for the work and breaking it down into terms that allows learning and understanding.

    I just came across your work a few weeks ago. It might be asking a lot but could you do a post or .pdf with the seriousness of the entire issue.

    I noticed on ENE the last few weeks or so the reading and everything are quickening. Could they have had another criticality underground ? If so, thats gotta open up more flow into the phytoplankton. An over view prom a pro’s perspective with cold hard facts.

    Something that will slap everyone awake. For me, all your post have detail & i like spending hours in study, but my friends family will not read more than one story. It’s gotta have meat with fact. They will not read 8 links talking about sfp, wonky a person like yourself has talent for teaching, that comes across for me.

    If I say something those around you , will not ” hear “.

    Ive seen stories by guys in the industry talking about rubber rings around spent fuel pool doors that need power so they hold air. No back up power, so we know the pools drained no matter what because of this.

    Maybe if you get time post something in this thread or a .pdf or a future thread.

    Either way your blog is fantastic. Peace.

  2. See ‘Russian Times, Feb. 16, 2014, New Mexico Radiological Waste Event’ for what is happening there today. The article itself says everything is hunky dory, of course, but the readers’ comments which follow it are interesting.

      • 🙂 Only one side of ‘us’ is shutting down, eh? INDEED! 🙂

        Watch out World,….for the ‘other side’ of ‘US’.

        Epically important that ‘we’ understand this,……and without a breakdown for 99% of us,…..we’d be undereducated,….and therefore, under-prepared!

        Let us remember this is a numbers game,…DETOX is the name of this game now. Stay ahead of ‘your lottery number’! We have the power to offset the **number** further on down the line,…but “it” won’t happen without careful attention to our ‘load’!

      • I like their methodology of Sr detection on page 5.
        Wondered if the Chlorine insisted on being added by Hellth Canadu was at least partly to hide the white “calcification” left behind by evaporated water where there was none for years previous to early 2012, in my humble witness. Now i know, at least elemental Chlorine does indeed react.

        For fish and other “wet” foodstuffs, i don’t understand why these are not thinly sliced, then dehydrated, a condensate collected of the water removed for sampling (may be nuclides there too!), then slices “scanned” for beta/gamma spectra for areas of interest to be studied later. Don’t know how alpha would best be measured. Capacitance, perhaps?

        Quoted from above article: “To explore the presence of such products in the current food supply, fish from the Pacific Ocean and a few various other foods were obtained at local San Francisco Bay Area retail locations in September 2013. Samples containing a significant water weight, such as fish and yogurt, were first baked to reduce the overall sample mass and enable easier handling; but the wet weight was recorded for reporting and use in analysis. Samples were then placed in plastic bags and counted in a cylindrical geometry at the face of a HPGe detector (2.1 kg p-type HPGe crystal, 85% relative efficiency) counted for a few days for each sample. For efficiency determinations, a calibration sample was created using a NIST Standard Reference Material– ‘River Sediment 4350B,’ which contains certified activities of 137 Cs, 60 Co, 152,154 Eu, 226 Ra, 241 Am, and others [14]. The uncertainties of the isotopes in the river sediment vary from 4 to 21%, where the primary isotope of interest for this set of measurements, 137 Cs, had an uncertainty of 6.4%. To achieve a volume similar to the food samples analyzed, 53.5 grams of the river sediment was thoroughly mixed with 141.7 grams of flour and counted in the same geometry.”

        Mmmm. River sediment and flour.
        Are they really so certain about those levels of uncertainty?
        Wouldn’t a large surface area make more radionuclides more resolvable? Just a high-school grad, but i did stay at a Holiday-Inne Expresso last night! 🙂
        Lamenting not having had a mathematics Professor like Dr. Gordon Edwards, though. The teachers i did have did care enough to go the extra mile. I thank them.

        …”wet weight was recorded for reporting and use in analysis”…
        …”Samples were then placed in plastic bags and counted in a cylindrical geometry”…

        Are those examples of how not to test foodstuffs?

  3. Bobby,
    I just wanted to comment publicly about the photos that appeared a couple days ago on enformable showing the cap still in place over reactor 3, after they’ve removed the debris and the bridge crane.

    They are faked. The cap in those pictures are photoshopped in.

    I cannot tell how much of the photo has been faked, but I can tell, in comparing to previous pictures that have been released, that some of the cap area is fake. you can also tell from the deepness of the black around the cap rim and the fact that no debris is left in the deep cracks – which is clearly impossible.

    I suppose anything from Tepco being fake should not surprise us, however i would like for folks to understand the depths to which they want to cover up (pun intended) the source of the #3 explosion.


    • Thanks, James. I suspected this also. We can’t trust Tepco to supply us with truth. I suppose that applies to the radiation measurements of the debris fragments, too… but I don’t know if they are swift enough to fake the ratios, as well how much radiation was in the fragments.

    • Huh? Um; which article to which are you referring.

      The first article is ISOE_News_21.pdf

      On the first page, they mourn the passing of “Mr Wataru Mizumachi, who passed away on October 29 , 2013.”

      Then they talk about the ISOE International ALARA Symposium:

      Quote: “Mr Furukawa (Tokyo Electric” [mofo] “Power Company) made a presentation entitled “Mid-to-long Term Policy for on-site Decontamination and the performance”, in which he introduced the present situation of the Fukushima Daiichi NPP site, the current decontamination activities and mid- and long-term decontamination plan. Moreover, Mr Frazier Bronson (CANBERRA Industries), who was involved in the response to the Fukushima accident from immediately after the accident, provided his experience in the presentation entitled “Radiation Measurement Experiences and Lessons to be learned in Response to the Fukushima NPP Accident.””

      Lesson #1 concerning lessons to be learned from Radiation Measurement Experience: If you want a job done right, we all have to do it ourselves (IMHO)!

      Quote: “In connection with the symposium, the participants had the opportunity to participate a technical visit in Fukushima Dai-ichi NPP. They were asked to wear protective clothing and half-face mask.”

      After all, as it clearly shows in the first picture on the left, at the bottom of page two; only the best budget half-assed 95% efficient HALF-face mask is strictly the very least they could reasonably do (under budget) – never mind the few whom had facial hair for which a half-face mask might as well have been no face mask (IMHO – and possibly that of OSHA concerning face masks & facial hare-kiri).

      Final Quote: “ISOE Expert Groups Reports” [:]
      “On 20th – 21st November 2013, the ISOE Management Board approved two expert group’s reports. The report on “Radiation Protection Aspects of Primary Water Chemistry and Source-term Management” reflects the current state of knowledge, technology and experience. With the approval of the report, the expert group was disbanded by the Management Board. The interim report on “Occupational Radiation Protection in Severe Accident Management and Post-accident Recovery”, which will be finalized during an International ISOE Workshop in June 2014, is to identify best occupational radiation protection approaches in strategies and practices. Limitations for developing effective management and national experiences for strategies of Severe Accident Management are to be incorporated into the final version of the report. Both documents will be published and made available for downloads through the ISOE Network web-site early next year.”

      JUNE??? NEXT YEAR???
      Good grief, Charlie Brown!
      With fiends like these, who needs enemas?

      If i am off-target; my apologies.
      If have hit head on the nail, Cue “The Donald”.

      Final thoughts.
      Instead of just Oxygen, is Chlorine a possible oxidizing agent during SFP#3 catastrophic explosion in March of 2011? This was no half-cell reaction, so am assuming those tables don’t apply here. The salt and hydrazine in the pool may be key. Was this combustion a consequence of or catalyst of what at-minimum seems to be a nuclear detonation though; i do not know. It does seem possible that the reactions which produce these chemicals in the first place could be reversible, though endothermic. :/

      There are many cells to be inferred in this multi-layer Sudoku, though. Is it unsolvable? NO. The truth will out.
      “Nukular” unprofessionals will to get they’re just deserts – devoid, eh? If you can’t dazzle them with their own bullshit, baffle them with the truth! The truth is a double-edged sword; it cuts both ways.

      PS: Please correct your link. Thank you FallOut. Of the 99%, there are too damn few like you and others here.

      PPS: Mourning the passing of Pastor Arnold Murray, February 12th.

  4. Metals activated by neutrons must also be addressed. Aluminum, carbon steel, stainless steel, Inconel, and Zircaloy are the most common. The later three will all contain significant amounts of Co-60 if they have had any appreciable irradiation history. From this easily measurable activity, and the approximate decay time since irradiation, the activities of passively immeasurable isotopes Fe-55, Ni-59 and Ni-63 can be calculated. Activated carbon steel probably cannot be detected passively and some limited sampling and laboratory analysis might be necessary to characterize Fe-55 and possibly C-14. A small amount of Fe-55 is also possible in irradiated aluminum.


  5. In remembrance of March 11th, 2011 – a day which will long live in infamy here on planet Earth, for many (if not all) nationalities, genders and ages.

    Quote: “Prof. Takeda “3/31/2015 is the last day of Japan””

    “Prof. Takeda Kunihiko from Chubu university roughly estimated anyone can no longer live in Japan after 3/31/2015.

    According to his explanation, the yearly dose will reach 5mSv/y (External dose and the slight internal dose) in 3 years and 4 months from January of 2012.

    He states, he receives radiation data from one of his readers. The person measures radiation three times a day, at work, doorway of house, and the living room in Mie prefecture (500km from Fukushima). Prof. Takeda admits the data is scientific enough.

    From the radiation level has been in the increasing trend since last September. In linear equations (y=ax+b), the average from January to March (=b) is 0.10 μSv/h, a is +0.004 μSv/h. y reaches 5mSv/y in 3 years and 3 months, so yearly dose will be over 5mSv/y in 3 years and 4 months from January of 2012, when is 3/31/2015.

    Prof. Takeda admits the data was collected by an individual and a and b are calculated by least squares but it’s rational enough.”

    quoted from: http://fukushima-diary.com/2012/04/prof-takeda-3312015-is-the-last-day-of-japan/

    Noting from netc.com that around Tokyo, the average individual reading is no less that 32nSv/h at Ishihara City, Iwasakinishi, Chiba. The highest average is 86nSv/h at Kashiwa City, Omuru, Chiba.

    If my math is correct, by multiplying those figures by 24 hours/day and 365.25 days/year (or 8766 hours/year) that equates to about 280mSv/y to 754mSv/y for those two locations respectively.

    Was Professor Takeda too conservative in his estimations?
    To me, it would seem so – at least for the area in and around Tokyo.

    To those that have suffered, including those whom have in-fact died, of the Sendai Earthquake, resulting Tsunami or concurrent ongoing Fukushima Mega-Disasters (which started during earthquake, yet causation even predates), i solemnly mark the coming date March 11th, 2014 in respect of your sufferings and those whom have passed on.

    May any nuclear mega-disaster never be allowed to reoccur.

    Also remember the “Angel of Miyagi”.

    Quote: “Miki Endo (遠藤未希), a 25 year old employed by the town’s Crisis Management Department to voice disaster advisories and warnings, was hailed in the Japanese news media as a heroine for sacrificing her life by continuing to broadcast warnings and alerts over the community loudspeaker system, located in the Crisis Management Department’s building, as the tsunami overwhelmed it. She was credited with saving many lives. The three-story headquarters of the department remained standing, but was completely gutted, with only a red-colored steel skeleton remaining; in the aftermath of the disaster, Endo was missing and was later confirmed to have died.[14] Photos show the roof of the building completely submerged at the height of the inundation, with some persons clinging to the rooftop antenna.”

    quoted from: https://en.wikipedia.org/wiki/Minamisanriku,_Miyagi

  6. Remember, remember!
    The eleventh, four months past November,
    The Nuclear treason and plot;
    I know of no reason
    Why the Nuclear treason
    Should ever be forgot!

Leave a Reply

Your email address will not be published. Required fields are marked *