Molten corium-concrete interaction at Fukushima.

The self-appointed Fukushima expert, manufactured anti-nuclear hero, and Fukushima minimizer Arnie Gundersen is now saying 20% to 30% of the cesium at the destroyed units 1, 2 and 3 of the Daiichi plant has escaped containment. According to Gundersen, this is a “game-changer” and maybe Fuku is almost as bad as Chernobyl now.

Well, forgetting the absurdity that Chernobyl is in any way comparable to Fukushima in scope, with enormous cesium contamination reported in Japan, with the entire North Pacific ocean polluted with radioactivity, sea lions dying and washing up on the west coast, Australia reporting 20% to 40% increases in background radiation two years after the catastrophe started (where Chernobyl was barely detectable there), we should note that everyone with at least half a brain knows there have been three melt-throughs at the plant, not a little dribble of corium that has escaped containment. Gundersen is denying the obvious, and is pretending to say something meaningful, in that his estimate far exceeds Tepco’s estimate that 1% of the cesium escaped, which is even more absurd.

On April 19, 2011, I published this note on The Japan Earthquake scribble:

Radioactive isotope concentrations from Takasaki CTBTO station http://www.cpdnp.jp/pdf/110408Takasaki_report_Apr2.pdf

xxxxxxxxx Ba-140  Cs-134   Cs-136   Cs-137     I-131      I-132     La-140    Te-129  Te-129m   Te-132 
3/15-3/16 312725  6921136   857713   5644666   14680552   11156850   1770189  2127038  22588878 27094139  

Note high levels of Ba-140 and La-140 on March 15-16. Lanthanum-140 is the daughter product of Barium-140.

(from Neeb, The Radiochemistry of Nuclear Power Plants With Light Water Reactors, pp. 518-519), The SFD 1-4 test was performed… “high-burnup fuel heated to high temperatures in a steam-starved environment”, “a small-break initiating event with limited steam supply to the fuel bundle was simulated”, “the post-test damage state of the bundle… appeared to be quite analagous to that of the damaged TMI-2 core”. If a TMI-style meltdown occurred, using Dr. Saji’s inventory figures (below), there would have been a 23:1 ratio of I-131 to Te-129m released. The Takasaki figures indicate a 1:2 ratio. The data do not support this scenario.

According to “TELLURIUM PRECURSOR EFFECTS ON IODINE TRANSPORT IN A BWR ACCIDENT” http://www.iaea.org/inis/collection/NCLCollectionStore/_Public/17/025/17025467.pdf
“This study describes the increase in iodine activity released to the atmosphere during a severe accident due to the radioactive decay of tellurium precursors… here it is seen that the iodine activity in the atmosphere is due disproportionately to I-132. Unlike the longer-lived isotopes, most I-132 (half-life of 2.30 hr.) existing early in the accident will decay before the significant atmospheric releases which follow reactor vessel failure. However, the supply is replenished by the decay of Te-132, which is released in large quantities from the drywell rubble.”

Takasaki is almost 100 miles from the Fukushima plant. Thus most of the I-132 which was released would be decayed. The large amounts of I-132 detected must have come from the decay of Te-132.

From p. 533, “Upon contact, the molten core material (the so-called “corium”) starts to react with the material of the basemat concrete… when the reaction zone is flooded with sump water… the highest temperatures might be reached… the molten-core – concrete interaction is the principal source of the release of the low-volatility fission products to the containment. The volatilization of these elements, such as barium, strontium, lanthanum, and cerium, is strongly supported by the gas bubbles which penetrate through the molten zone.”

Note again the high concentrations of barium and lanthanum, and that of tellurium.

Conclusion: The emissions observed at Takasaki were not due to a TMI-style accident, but one in which corium interacted with concrete and water. This released significant concentrations of barium, lanthanum, and strontium into the atmosphere.

This is based on CTBTO data, not Tepco data.

Species	Half-lives	Fukushima 1F2-5
Ru-103	39.3d	2805(PBq)
Ru-106	368d	640
Sr-89	50.5d	2649
Sr-90	29,12y	171
Kr-85	10.72y	21
Te-129m	33.6d	774
Te-132	3.26d	3333
I-131	8.04d	2292
I-133	20.8h	4985
Xe-133	5.25d	4844
Cs-134	2.06y	126
Cs-136	13.1d	82
Cs-137	30.0y	193
Ce-141	32.5d	4130
Ce-144	284d	2917

So it was obvious early on that there had been a molten corium-concrete reaction in units 1-3. The conclusions were based on CTBTO measurements, independent of Tepco, whose (faked) measurements Gundersen has been mostly using. Arnie is still denying any significant interaction with corium and concrete.

Going on to p. 533 of the Neeb document, simulations involving corium-concrete interactions are described in more detail. The first step of the molten core-concrete interaction is high-temperature decomposition of the concrete accompanied by the production of gases, mainly H2O and CO2, followed by melting of the concrete materials and their incorporation into the melt. As a consequence, the erosion of the concrete will start with the formation of a cavern, in which the melt separates into two phases, a lower metallic one which is covered by a lighter oxidic phase, with the former containing metallic fission products like ruthenium, technetium, palladium, and the latter containing barium, strontium, and other oxides… The heat production in the oxidic phase of the melt is mainly due to fission product decay heat, whereas in the metallic phase the exothermal metal-water reaction is the main contributor.

Due to the very high temperatures prevailing during this stage of the accident, the molten core-concrete interaction is the principal source of the release of low-volatility fission products to the containment. The volatilization of these elements, such as barium, strontium, lanthanum, and cerium, is strongly supported by the gas bubbles which penetrate through the molten zone… In addition to the comparatively high temperatures, the changed chemical conditions are also responsible for this enhanced aerosol production.

The first table above represents an estimate of the percentage of elements released into air and water, using standard nuclear fuel. Note that less than 0.1% of the strontium (Sr) is released. Now, according to Dr. Saji, there are around 7 times more becquerels of strontium in the fuel inventory than cesium. In a previous post, Strontium-90 in the Pacific, it was found that by June 2011, strontium-90 levels in the Pacific were 2.65% that of cesium-137. This is considerably more than predicted, and indicates a much more severe accident than the authors had simulated.

A study released recently found that large amounts of radioactive silver, Ag-110m, have been detected. According to the table, 3% of the silver would have been released. This also indicates a more severe accident than contemplated before.

The second table indicates simulated radioactive releases using MOX fuel, which was used in unit 3. Here 97% of the silver is released. Also note that 87% of the noble gas krypton-85 is released in this scenario. The entire inventory of the noble gas xenon-133 was released from the plant within the first 5 days of the catastrophe. It was further found that more than 100% of the xenon was released, which begs the question of further meltdowns that we have not been told about. See The mystery of the extra xenon-133.

But the most important thing to notice is that in both simulations, 100% of the cesium is released during the melt-throughs. This means that all of the cesium that has been released from the plant since the early stages of the catastrophe is coming from the spent fuel pools.

Cesium levels in river sediment near Kashiwa jumped by 3,700% in 3 months recently, according to Fukushima Diary. Fog in Tokyo deposited over 4,000 Bq/kg of cesium in one day, recently. Some of the cesium is being resuspended into the atmosphere by the burning of contaminated tsunami debris, but it must be that the vast majority of the cesium released into the air and sea is from the pools.

You have to wonder if this is even possible with semi-functioning spent fuel pools. Maybe some or all of the contents of the pools leaked out of them early on, and what we have here is a slow-motion meltdown event in pools 1-4, and the common pool. SFP 1 and the common pool contain an enormous amount of cesium. Since no independent scientific organization has been allowed into the Daiichi plant (contrary to Japanese law), we have no way of verifying that the pools are actually intact.

The underground coriums are leaking strontium, americium, uranium, and plutonium. Re-criticalities in these coriums are releasing iodine-131, iodine-129, and a host of other isotopes into the air and sea. The ratio of strontium to cesium in seawater, previously at 2.65%, has now reached 44%.

It should be clear that Arnie Gundersen, who by all accounts is a competent nuclear engineer, is deliberately distorting the facts in an egregious manner. Any anti-nuclear persons, organizations, and message boards that support him should also be questioned.

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