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FVCOM
FVCOM: Chen's Lab, UMassD

MEDM Assessment of Japan's Tsunami Event and Impacts of Radionuclides on the Pacific Ocean

March 11 2011 was a tragic day for Japan and the world. The earthquake in Tohoku, Japan caused a tsunami, and the resulting tsunami-induced inundation has placed Japan into crisis. The amount of radiation released in the nuclear accident has threatened the coastal environment with potential impacts on the Pacific Ocean. An international research team was established with the aim of studying the mechanism of the tsunami, simulating the inundation, and assessing the impact of radionuclides on the surrounding countries around the Pacific. The team members include Dr. Changsheng Chen (Physical Oceanographer), Dr. Zhigang Lai (Physical Oceanographer), and Ms. Huichan Lin (Physical Oceanographer) at University of Massachusetts-Dartmouth (UMASSD)-USA, Dr. Robert C. Beardsley(Physical Oceanographer), Dr. Jian Lin (Geologist) and Dr. Rubao Ji (Biologist) at Woods Hole Oceanographic Institution (WHOI)-USA, Dr. Jun Sasaki at Yokohama National University-Japan and Dr. Chunyan Li (Physical Oceanographer) at Louisiana State University. The ocean model used for this activity is the global-coastal nested FVCOM model system. FVCOM is an unstructured grid Finite Volume Community Ocean Model (FVCOM) developed originally by Chen et al. (2003) and is being upgraded by the UMASSD-WHOI joint FVCOM development team (Chen et al., 2006a,b). Dr. Sasaki successfully applied FVCOM to simulate the 2004 tsunami and inundation in Banda Aceh in the Indian Ocean.

The Unstructured Grid Finite Volume Coastal Ocean Model [FVCOM] is a prognostic, unstructured-grid, finite-volume, free-surface, 3-D primitive equation coastal ocean circulation model developped by UMASSD-WHOI joint efforts. [See: MEDM Home for a full description.]

This impressive modeling tool has been produced an array of very nice graphic models - some with animation - of both the tsunami inundation of Fukushima Daiichi, but also particle tracking at eight depths from surface to 1200 meters for tracking contamination from Daiichi around the Pacific rim, and includes predictions for affects on the western coast of North America. The model projects out to seven years. There is a good explanation of how suspended particles move at the various depths which is worth absorbing before viewing the actual models for each level of currents, and suggest that radionuclides in the deep waters could be upwelled to the upper water column to then disperse over a broad region of the north Pacific. These are based on particle tracking experiments conducted by Z. Lai and C. Chen, Physical Oceanographers at the University of Massachusetts-Dartmouth; and R.C. Beardsley, Physical Oceanographer at Woods Hole Oceanographic Institution.

The projection of upwelling from deeper currents is significant because of the presence of heavy particles in the waterborne releases from Daiichi, now estimated by TEPCO to be in the range of ~450 tons per day, exiting the facility outside the bounded 'lagoon'.

These heavy particles are not just suspended heavy metal isotopes like uranium and the actinides (such as Plutonium), but actual particles of fuel that used to be in the assembly fuel rods in the three 100% melted reactor cores and all of the spent fuel in all of the plants' SFPs, which were known in the first days of the disaster to have lost large volumes of cooling water and overheating of elements, to the point that zirconium fires were reported burning off and on in at least two SFPs.

The U.S. NRC has known about the problem of fuel fragmentation during LOCA accidents for a long, long time. The details were written up for NUREG-2121 in March of 2012 (one year after the meltdowns at Daiichi) in a document entitled Fuel Fragmentation, Relocation, and Dispersal During the Loss-of-Coolant Accident by the Office of Nuclear Regulatory Research. Under section 5.2.4, Radiological Effects of Dispersed Fuel Material, a not-happy consequence is described...

Even after a successfully terminated large-break LOCA, where all safeguard systems have worked as planned, a number of fuel rods will have failed (Ref. 61). Large amounts of radioactivity are assumed to have reached the containment in the form of volatile or noble gases, and also particulate aerosols, which would transport other radionuclides trapped in the fuel material. From a regulatory point of view, some of this radioactivity will leak out of the containment and reach the environment outside the nuclear plant, where it will cause a dose burden to the public. In the traditional design-basis regulatory calculation, it was assumed that the containment leak rate is the highest permissible rate stated in the technical specifications or license conditions of the plant.
[Emphasis mine]. What this means is that the NRC recognizes that in a large-break LOCA, it won't be just the volatiles and nobles that get out and expose the public, it will be these actual dust-size fuel particles as well. When your reactor plants actually blow sky high, as four of them did at Daiichi, all bets and estimates are off on how much of this crap gets out in the air to contaminate vast regions of land and all the people/animals living there, as well as into any water sources nearby - in this case, the Pacific Ocean.

The NRC in its "Conclusions" of course concludes that "more research and detailed analyses are required," which is of course their conclusion to every fatal flaw ever discovered and recorded with nuclear technology from its very beginnings. They know they can't actually "regulate" this sort of thing, because nobody can turn one of these beasts OFF in the midst of large-break LOCA events. The shit gets out, so the officials and regulators just get to lie about it with the requisite reassurance attached to All Things Nuclear - "No Immediate Danger To The General Public."

It's that gratuitously inserted modifier "immediate" you need to look out for. If you're not getting vaporized on the spot, radiation's worst effects take awhile...

The tendency for those little cylindrical fuel pellets in those zircalloy-clad fuel rods to "fail" by means of structural disintegration into fuel particulates has been a regular big deal issue in the industry since forever. The concurrent tendency for the zircalloy cladding to overheat, swell and develop leaks (usually along lousy welds) wherever individual pellets have disintegrated is also a long known issue for the industry's attempts to manage contaminant levels both inside the plants and what is released to atmosphere or water every single day of operation.

In fact, in our own investigation reports to Congress/NRC about the nature and consequences of the 1979 accident at Three Mile Island, we traced causal factors well past the multiple-point failures of equipment that caused the initial system failures, but all the way back to the origin of the core itself and problems it had been causing in the few weeks following start-up (and before the accident) with increased contamination and leak rates the utility was years later convicted in criminal court for covering up. Warpage and deformation of the rods due to failed fuel and associated cladding failures in a technological engineering 'marvel' with control rod descent tolerances measured in microns (really), is what we concluded had prevented the control rods in the hottest central region of the core from descending properly to stop the fission reaction when loss of heat exchange feedwater signalled the initial scram. And that is what caused about half of the core to melt into a puddle of corium ooze on the bottom of the reactor vessel.

They've been not-quite "researching" the common fuel failure phenomenon ever since, apparently, and not reaching any conclusions other than that more research needs to be done. Ah, well. At least Kerr-McGee is no longer in the fuel fabrication/core manufacturing business. That's something, I guess.

In the months since Japan's new nuclear regulatory agency came into being and power, TEPCO has been forced to report a bit more regularly and honestly about conditions at Daiichi. In a press release on August 19 of this year detailing the water leak from the tank farm [follow-up 2], they did finally report that nuclear fuel material (not in the form of gas) was in that leakage from the tank[s]. It's in ALL the tanks. Which means that whatever filtration they may have said they've been using to remove cesium somehow missed filtering these actual chunks of reactor fuel. Surprise, surprise. It's going out to sea.

Now we have the above really nice models generated by serious oceanographers to predict the movement of everything from suspended light radionuclides (like tritium, cesium, strontium, etc.) as well as heavy particles of fuel material that will for awhile during transit be hovering in much deeper currents. These do not bode well for the amazing amount of 'reassurance' we are getting from the nuclear industry's current big-push propaganda campaign, about how it's all over, no harm done, everything's fine and dandy.

Do with the data and projections what you will, per any possible protections you may wish to institute for yourself and your loved ones based on reality instead of nuclear fairy fantasies. The dangers will be with us essentially forever, so people do need to take some things under consideration about how - and where - they will live their lives for the next 7-10 generations or more. There are effective ways to diminish exposures, avoid exposures, and even mitigate exposures. None of these things can be done if the fact that exposures are happening is denied in toto, or 'authoritatively' pronounced to be inconsiderable.

Best of luck to all of us, and Merry Christmas!
___

[H/T to EneNews aggregator]

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